FAO FORESTRY PAPER
8
establishment techniques
for forest plantations
by
g.w. chapman
and
t.g. allan
forest resources division
forestry department
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
ROME 1978
First printing 1978
Second printing 1981
The designations employed and the presentation
of material in this publication do not imply the
expression of any opinion whatsoever on the
part of the Food and Agriculture Organization
of the United Nations concerning the legal
status of any country, territory, city or area or
of its authorities, or concerning the delimitation
of its frontiers or boundaries.
M-31
ISBN 92-5-100535-4
The copyright in this book is vested in the Food and Agriculture Orga-
nization of the United Nations. The book may not be reproduced, in whole
or in part, by any method or process, without written permission from
the copyright holder. Applications for such permission, with a statement
of the purpose and extent of the reproduction desired, should be addressed
to the Director, Publications Division, Food and Agriculture Organization
of the United Nations, Via delle Terme di Caracalla, 00100 Rome, Italy.
FAO 1978
-iii-
FOREWORD
FAO is indebted to G.W. Chapman and T.Q. Allan for the preparation of
this document on establishment techniques for forest plantations. The first
draft was prepared by Mr. Chapman, a forestry officer of many years 1 experience
in the Mediterranean and Near East regions. It was based largely on the papers
submitted to the FAO World Symposium on Man-Made Forests and their Industrial
Importance f held in Canberra, Australia, in 19^7 f and supplemented by other
available information. The draft was widely circulated, and many useful
suggestions were received for its refinement. In the light of these comments,
and with the aid of more recent literature, the document was revised and
updated in 1977 by Mr. Allan, who also drew on his long experience of
afforestation in Africa.
Appreciation is also expressed to H,C. Dawkins, L.R. Letoumeau, A.I.
Fraser and B. Kingston whose work is reproduced in the appendices.
Louis Huguet
Director
Forest Resources Division
-V-
TABLE OF CONTENTS
Page
Foreword iii
Preface vii
Site preparation 1
General considerations 1
Manual methods 2
Mechanization and mechanized methods 11
Draught animals 32
Chemical methods 33
Direct sowing 43
General considerations 43
Pre-sowing treatment of the seed 44
Seed coating and pelleting 47
Site preparation 47
Times for sowing 48
Direct sowing methods 48
Planting and tending 53
Planting 53
Tending operations 68
Special techniques for difficult sites 79
Sites where soil and water conservation measures 79
are critical factors in forest establishment
Irrigated or irrigable sites 9
Sand dune sites 99
Wet or waterlogged sites 103
Mine tips and spoil sites 111
Protection 121
Weather conditions 121
Insects and fungal pests 122
Animal damage 125
Fire protection 127
Plantation planning 135
Introduction 135
Plantation management planning 126
Collection of data for the plantation management plan 136
The plantation management plan 139
Annual programme of work 146
-vi-
Page
Appendices
A. Criteria for successful line planting 149
B, Guidelines for the design and establishment 151
of plantation roads
C An outline of equipment and materials for 160
an afforestation project
D. Planning of seed collection and handling 161
E. Network analysis 164
F. Medium-term forecast of work 169
G. Sample distribution of monthly labour 170
requirements
H. Plow chart of cost records 171
General bibliography 17.
Index 1 f ,
-vii-
PKEFACE
The PAO World Symposium on Man-Made Forests and their Industrial Importance,
convened in Canberra, Australia, in 19^7 * drew attention to the increasing contribution
of man-made forests in the field of forest development and wood production. Estimates
made at the time of the symposium were that a world total of about 80 million ha of
man-made forests had been planted up to 19^5? and that by 1985 the total might well
reach 200 million ha (FAD, 196?) In some countries of the world, a substantial part
of the national wood consumption is already met by wood production from plantations,
and in other countries there is a growing recognition of the possibilities and
advantages offered by man-made forests, even where considerable reserves of natural
forest exist.
This document is intended to serve as a reference book on some of the principal
methods of establishing forest plantations. Coverage is global, with some emphasis on
techniques suitable for tropical and subtropical regions.
For the purposes of this book, the plantation establishment phase is considered
to be that general period from initial site preparation to the stage when the plantation
crop closes oanopy. The book, therefore, covers site preparation, planting and direct
sowing, early tending and protection operations, as well as the necessary operational
planning measures required to ensure timely and efficient completion of activities.
Subsequent managerial practices carried out after canopy closure and operations done
prior to site preparation, such as nursery production and choice of species and sites,
have been excluded.
The subject matter is treated on a broad base, covering the main techniques and
general principles of plantation establishment and operational planning. Greater detail
on specific practices for particular areas oan be found by consulting handbooks or
manuals prepared for individual regions or projects, many of which are listed in the
extensive bibliography provided at the end of each chapter. An additional bibliography
of general, comprehensive sources of information is given at the end of the book.
-1-
GH AFTER 1
SITE PREPARATION
GENERAL CONSIDERATIONS
Site preparation as discussed in this chapter is confined to firm, well-drained or
generally dry land sites, already occupied by a usually indigenous ground cover (more
difficult sites are dealt with in Chapter 4). This vegetative cover can sometimes prevent
the successful establishment of a new plantation crop by occupying and utilizing the
required land, by creating excessive competition for available moisture and/ or nutrients,
by depriving seedlings of light or by hindering the introduction of techniques necessary
for successful establishment. Under such conditions, a primary requirement is to determine
efficient and economic methods of eliminating harmful competition. Sometimes removal of
vegetation creates sufficiently favourable conditions for tree establishment without
further assistance, but in other areas the main aim is to create conditions whereby
regrowth and weeds can readily be controlled during the establishment period, which may
cover a number of years. Site preparation is an early investment and often constitutes a
major proportion of total establishment costs. The fact that such costs considerably
affect financial feasibility underlines the need to use efficient and economic methods.
As the removal of an indigenous vegetative cover constitutes a major ecological
change, no site clearing should take place without knowledge of what these effects are
likely to be andwithout careful planning to ensure that cleared land is carefully and
efficiently used and that necessary precautions are taken to prevent soil degradation or
erosion.
In certain favourable circumstances, it may be possible to establish the
plantation crop with minimum disturbance of the natural cover and minimal or no
cultivation of the soil. For example, where fast-growing tropical pines are planted on
short-stemmed grass sites, it is common practice to plant the seedlings without prior
cultivation, the only preparatory work being to bum off the grass in the dry season
preceding planting. At the other extreme, there are examples where dense tropical rain
forest has to be removed, often under difficult conditions of climate and terrain, before
planting can begin. Often the soils of such rain forests are fragile and great care has
to be exercized if excessive erosion is not to ensue. Between these extremes, there is a
great range of sites and conditions offering a number of options on how site preparation
may be undertaken.
-2-
Site preparation using labour and hand-tools is the oldest and remains the most
common method. More recently, particularly where the labour supply is restricted or
costly, a number of mechanized techniques have been developed, many involving specialized
equipment for clearing and cultivation. Site preparation in forest or woodland,
particularly in hot climates, is extremely arduous and heavy power units can take some of
the drudgery out of such work. Machinery offers high outputs per hour or per day, but
involves a high capital expenditure and requires special operating and maintenance skills*
A further innovation is the development of chemical weedicides which can be used in
forestry to control or eliminate unwanted vegetation. Some chemical methods are used on
an operational scale, but others remain at the experimental stage; for many there is
incomplete information of their possible harmful effects on the general environment.
For any afforestation project, site preparation methods should be investigated,
developed and assessed prior to initiating the project. In many countries, adequate
manual techniques are established and known, but for some operations the employment of
mechanized or chemical techniques may offer improved cost efficiency or opportunities to
extend the scale of project. In the absence of any previous site preparation investig-
ations, a series of trials is required to compare the standard local techniques with other
methods which seem relevant to the sites being developed. The comparisons should be made
on the same or highly similar sites and should not be confined only to site preparation
but should relate the operations to subsequent establishment, tending and growth.
The general objectives of site preparation involving clearing of vegetation and/or
cultivation are:
1) to clear the site of existing vegetation so as to reduce or eliminate
competition which could prevent adequate establishment or adversely
affect the plantation crop and
?) to cultivate the ground
a) to facilitate planting and establishment and to encourage
rapid root development,
b) to reduce the weed cover,
c) to reduce erosion by providing physical barriers to surface
runoff and,
d) where me ch -mi zed post-planting weeding is planned, at the
time of cultivation or before to remove all surface or
below ground obstructions likely to hinder weeding operations.
Under specified conditions only some of these objectives may apply to a particular
area or project.
MANUAL METHODS
Manual methods for clearing ground cover and for soil preparation are in use
predominantly under the following circumstances:
1) where the ground cover requires a minimum of disturbance prior to
planting or seeding,
2) where labour is plentiful, cheap and efficient or f in some cases,
where it may be socially desirable to employ labour in preference
to other alternatives, and
-3-
3) where machinery is not available or where the terrain is too
steep, too rooky, too wet or otherwise unsuitable for its
operation.
Grass or Shrub Covered Sites
Direct Planting without Clearing
On seme sites where the ground cover consists predominantly of grass speoies or
of low f shrubby speoies f direct planting may be carried out with a minimum ef previous
site preparation. Such is the case in the pine plantations of Zulu land in South Africa
where pines originating primarily from southern U.S.A. (Pinus elliottii) have shevoi a
remarkable capacity for growing up threugh the undisturbed mature grass, provided that
their tops are kept free by slashing. No form of soil preparation is needed and the
plants are simply inserted into holes or slits made with a trowel.
Direct planting without previous site preparation is also practised in many
northern temperate countries, for instance on old clear-felled conifer forest land or
dry heath moors, where soil nutrients and moisture are sufficient both for the newly
planted seedlings and for the native vegetation. Sometimes the retention of ground
cover is even desirable because of its beneficial affect in protecting the young forest
plants from frost or from exposure or in reducing the risk of erosion on steep or hilly
sites. The essential feature in the direct planting method is that the forester relies
mainly on post-planting weeding and slashing to keep the forest plants from being
suppressed by the native vegetation.
Strip and Patch Clearing
In cases where the competition of herbaceous or shrubby vegetation is harmful to
the new forest crop, as happens frequently in the Mediterranean region and other areas
subject to pronounced dry seasons, it is necessary to clear the vegetation prior to
planting. Where burning cannot be safely managed and where it is too costly to clean
cultivate the whole area, clearance of the vegetation is limited to relatively small
patches or narrow strips, in which the tree seedlings are later planted. The cleared
patches or strips should not be less than one metre in width, preferably 1.5 metres, and
should be well cultivated to good tilth before sowing or planting. The tools most
commonly used for this work are the mattock, heavy hoe and grubber. Most effective is
the mattock, which has a hoe or digging blade on one side and a pick or cutting blade on
the other.
On hillsides liable to erosion, the cleared patches and strips are usually sited
on the contour, the uprooted vegetation being stacked along the lower edge as a
precaution against soil wash. Where soil conditions permit, contour strips can be
ploughed.
In Morocco, the soil preparation method most used in shrub-covered foothills for
planting Eucalyptus gcmphooephala and Pinus hale pens is is to clear and cultivate by mattock
patches of land (pot ets) 50 - 70~om2. Frequently these cultivations are combined with soil
and water conservation measures such as contour ditching or construction of narrow terraces
(gradoni or banquettes).
Burning Off
Controlled burning of grass or low bush covered sites prior to planting is common
practice in many countries and can be said to be the oldest method of ground clearance and
may be the cheapest. Controlled burning requires careful planning. The general approach
involves cultivating or clearing a fire line or break around the area and initially burning
-4-
a strip at least 50 m wide into the wind, with the fire being kept under control by beaters*
Qnoe a sufficiently large downwind strip is clear of inflammable matter, the rest of the
perimeter is set alight and the fire is allowed to run with the breeze. This main burning
is best done in the evening or at night when winds generally drop and the fire is less
likely to get out of control.
Burning in some cases may be harmful, for instance by stimulating the regeneration
of undesirable species, by aggravating soil erosion or by promoting the outbreak of fungus
diseases (e.g. Rhizina undulata on Pinus sylvestris).
Bush or Forest Covered Sites
On sites covered with woody vegetation there are two major clearing techniques :
1) felling, where roets are left in the ground or 2) stumping, where the roots are
extracted.
Felling without Root Ertraotien
Clear Felling
The clearing of more or less densely covered bush or forest land is almost invariably
costly in manpower, though the financial cost to a project may be reduced if a good
proportion of the wood being cleared carries some commercial value as firewood or charcoal,
posts, poles, pulpwood or even timber. In such oases, the land clearing operation is often
contracted. The forms of such contracts naturally vary widely throughout the world, with
much depending on the value and usefulness of the material to be cleared. In favourable
circumstances, clearing may yield a net income, recouped either in cash or commuted for
additional site preparation work such as fencing, draining, or construction of access roads.
In other areas, the site to be prepared for planting may be previously logged
forest in which all or most of the usable material has already been removed, leaving only
the felling debris mingled with unmerchantable stems, weeds, coppice sprout s f an under*
Btery forest or bamboos. There is then little alternative but to move in with gangs of
men to out and clear the vegetation for broadcast burning or to pile it in heaps or rows
where it can be burned or left to rot.
In Papua New Ghiinea, native rain forest is clear-felled from plantation sites by
manual methods. Labourers first go through the area cutting all ground vegetation and
stems up to 7*5 om diameter. This clears the way for the next gang of men who fell all
the stems above this diameter and at the same time trim off the branches from the larger
felled trees* Some six to eight weeks later, during a few days dry spell, the out-over
areas are systematically burned, and generally all but the heavier logs are consumed.
The brushing and felling work alone requires up to 50 man-days per hectare.
In Ghana, tropical high forest is also manually cleared for planting. Following
selective logging, understocked sites are cleared of underbrush and small trees by gangs
of labourers using machetes. Larger trees are felled with power saws or poisoned. Some
de-limbing is done in association with felling to facilitate a good burn, but stacking and
windrowing are not practised. Broadcast burning is done in the dry season. The felling
and burning operation require an average of 86 man-days/ha.
Similar large-scale manual clearing of commercially poor lowland tropical rain
forest is done at the Jari River project in the Brazilian Amazon region, where large gangs
of closely supervised contract labour have replaced heavy tractors (Palmer, 1977).
In Papua New Guinea, Ghana and Brazil, the species subsequently planted are light-
demanders. These require total felling of existing vegetation, but with more shade-tolerant
speoies it may not be necessary or even desirable to remove all the indigenous forest growth
from the site. Consequently, systems of partial clearing have evolved which may be called
"strip or line clearing 11 where the vegetation is totally cleared along lines or bands at
fixed intervals, and "release clearing for underplanting 11 in which the ground vegetation
and understory species are totally cleared while the overstory of larger stems is thinned
out systematically so that the crowns of the remaining stems cast a mosaic pattern of light
and shade on the ground*
Strip Clearing
Strip clearing has been widely used in the tropics in connection with : 1)
enrichment planting, aimed at improving the percentage of desirable timber species in
natural forest without eliminating existing useful trees and 2) conversion planting, aimed
at the complete replacement of the existing vegetation by an entirely new man-made forest
(FAO, 1970 ) Although these two reforestation methods differ in aim, the techniques used
are often very similar. For both, fast-growing, light -demanding trees are planted in lines
cleared through the existing forest after varying reductions in the canopy; for enrichment
planting some of the trees of the natural forest are intended to be preserved, while for
conversion planting all are eventually removed. The width of the cleared strips and their
frequency varies, but the method of carrying out the work is essentially the sarae.
The first step is to establish a cleared base line (if no roads or suitable paths
are available) at right angles to the direction of the future planting lines. This
direction may be determined by considerations of topography, of future extraction routes or
of lateral shading (in many West African countries an east-west orientation is preferred).
The planting lines are then "blazed out" at right angles to the base line by a brushing
gang, the correct direction being maintained by a prismatic compass or a simple sighting
instrument. The blazed lines are then cleared to the required width by cutting and
felling gangs. The resulting debris is piled to rot along one edge of the strip or,
preferably, burned if atmospheric conditions permit. The cleared strips are hoed in lines
or in spots ready for planting or sowing. Trees in the bands of forest between the cleared
stripe which may cast overhead or lateral shade on the planted trees are either felled,
ring-barked (i.e. girdled) or poisoned, the intensity of removal depending on whether the
objective is enrichment or conversion.
Although line planting has been widely practised in the tropics, it has met with
varying degrees of success; there have been a number of attempts to identify the reasons
for success and failure (Catinot, 1969; Davdeins ex Lamb, 1967; Groulez, 1976; Jackson,
1974 and Lamb, 1969)* Most successful have been the line conversion plantings in
francophone West Africa. Line enrichment planting, on the other hand, has been abandoned
in some countries, after having been practised for a number of years. In some cases this
is because the techniques used were unsuccessful; but many of these failures could have
been avoided had the general criteria for success as formulated by Dawkins (ex Lamb, 1967),
and reproduced in Appendix A, been followed. In particular, early and complete opening of
the overhead canopy and the use of species capable of rapid initial growth and tolerant of
weed competition are necessary (Jackson, 1974) In other cases the increased demand for
forest products, especially from thinnings, has made close plantations more attractive than
line plantings. On the whole the tendency is to change from line plantings to more intensive
forms of forest management, such as close plantations or taungya plantations. Line planting,
however, is still used extensively in some countries and remains under study in a number of
others. It can still be of great value in regenerating exploited forests when more
intensive management is uneconomic or where natural forest conditions must be maintained to
protect the environment.
-6-
In the British Solomon Islands Prtteotorate f for example, line planting has become
the standard technique for large-scale reforestation of cut-over native forests (Jacksen,
1974). Lines are out 3 m wide at 13 m intervals and the plants are spaced 3.6 m along the
line. All stems in the remaining overwood larger than about 5 cm diameter which cannot be
felled economically with a machete are frill-poisoned with sodium arsenite two months after
planting. The first two line cleanings are done to ground level at 2 - 3 month intervals.
Subsequent cleanings are done to knee height at 3 - 4 month intervals during the first 18
months. Thereafter climber cutting is practised as required. In 1970 labour requirements,
excluding supervision, were 55 man-days/ha, broken down as follows:
Operation Man-days/ha
Site preparation (line clearing, poisoning,
regeneration roads) 19
Planting and plant production 11
Tending (cleaning, climber cutting, boundary
maintenance) for three years 25
Release Clearing for Underplanting
This method may well be considered as an extension of, or deriving from f the
European system of shelterwood regeneration. It has application particularly where!
1) the species to be introduced needs (or tolerates) overhead shelter
in the earlier years after planting,
2) the existing forest contains a relatively high number of large,
undesirable stems whose removal would be unduly costly or
difficult, or
3) the existing forest contains a number of valuable timber species
which it is desirable to retain, the aim of new planting being
either to enrich the forest with the same species or to introduce
a replacement crop of some other species,
The usual procedure is to brush or cut away all the low vegetation (small coppice
and trees under 10 cm diameter) which is then piled and, where possible, burned, leaving
the ground surface more or less freely accessible for tree planting. Some of the
remaining trees are then ring-barked, leaving sufficient stems in the overwood to produce
the desired mosaic of light and shade of the forest floor. The remaining overwood is
killed off selectively by ring-barking in subsequent years, depending on the progress of
the underpl anted crop. The ideal density of the overwood is one which maintains
sufficient shade to keep the forest floor reasonably free from weeds and coppice
regrowth while letting in sufficient light for satisfactory establishment of the new
forest crop.
Ring-barking is most effective if carried out in the season of active growth.
Care should be taken to remove a complete band of bark, cutting through into the wood
of the stem to ensure that the cambium is completely severed. There are many species
which are not killed completely in the first year after ring^barking and linger for
several years before finally dying. It is becoming an increasingly common practice to
ring trees by chemical methods, as described later in this chapter.
-7-
Unless the over wood sterna have some commercial value, in whioh case they would be
felled and extracted through the young underplanted forest, normal practice is to leave the
dead overwood stems to "rot on their feet"! the side branches fall off gradually when rotten
and finally the hulk of the old trunk falls; damage to the new plantation is usually
negligible. However, on steep slopes experience has shown that the trunk, when it eventually
falls, can roll and cause considerable damage to the young crop. There is also the problem
of the danger of falling branches from the dead trees whioh makes labour reluctant to work
in treated areas.
One example of underplanting after release clearing, can be found in the United
Kingdom where Tsuga heterophylla is often planted under existing hardwood cover such as
birch (Betula), old oak (Onerous), coppice or ash (Praxinus).
Stumping
Stumping is necessary where it is envisaged that there will be subsequent
cultivation, often mechanized, requiring the elimination of roots. Manual stumping is the
oldest and most common means. The work may be done by direct or contract labour using,
for the most part, spades, hoes, mattocks and axes. The operation involves excavation,
cutting of roots and felling and in most instances includes removal of the whole standing
tree at the time of stumping. The soil from around the tree is dug out; the depth and
the width of the excavation varies with the size of tree and root system. On completion
of excavation, the lateral roots are severed and the tree is then felled by cutting the
taproot. In Nigeria, output varied with unit basal areas savanna with a basal area of
9 m^/ha required an average of 65 man-days to stump one ha whereas heavier woodland at
13 m^/W required 123 man-days (Allan and Akwada, 1977).
Manual stumping is an arduous and highly labour intensive task, still widely
practised in African savannas. (Courtesy T.G. Allan)
-8-
Disposal of Debris
When the felled vegetation is sufficiently dense to support a hot "burn, it oan be
burned in place without piling on windrowing. In other areas, labourers out and clear the
felled material and pile it into heaps or rows clear of the planting lines where it oan be
burned or left to rot. If the piled rows are not burned, gaps should be left at intervals
to allow ready access for tending or for fire fighting. For burning, the debris is often
piled into windrows or out into billets which are heaped into tight piles and stacked
around the larger timber to facilitate ignition and burning. The burning of windrows is
described further on page 21 f and the subsequent operation of plantation layout is treated
on pages 59 and 142.
When clearing occurs close to centres of population, it may be possible to dispose
of this debris as firewood, which is not only sound utilisation of the resource but can be
socially and economically beneficial to the plantation project. Opening areas to charcoal
production is another possibility. Charcoal production allows a more complete utilization
of the debris than firewood, and being lighter oan extend the economic transport distance.
Taungya
Agri silviculture may be defined as a system combining agricultural crops and/ or
livestock with growing trees, with the aim of optimizing the total production per unit
area compatible with the primary objective and sound land use. Within this concept may
be included the taungya, or ahamba, plantation system where a forest crop is raised in
combination with a temporary agricultural crop. Under this system, manual site preparation
is carried out by cultivators who use the land for food production during the period when
the plantations are being established.
Taungya is a Burmese word for a cultivation plot of the type of shifting
oultivatien practised in the hilly evergreen forest areas. Shamba is the Kiswahili word
for a similar clearing in savanna or forest in East Africa.
The taungya plantation system is very often developed in tropical areas where
shifting cultivation is common. Shifting cultivation is a primitive but effective form
of agriculture where land is unlimited. The essential features are land in which the
level of fertility is quickly diminished under cultivation, and where even if artificial
fertilizer oculd be effective the cultivators are too poor to afford them. Instead of
fertilizers, a tree fallow is used to replenish fertility* However, wherever land is
limited in relation to an often expanding population, the cultivation cycle is shortened,
with consequent losses in fertility, and soil degradation often ensues.
The development of the traditional taungya plantation system is only possible
where there is land hunger and industrious, landless cultivators,* Under this systam, the
cultivator is allotted an area of natural forest which he clears by stumping, cutting and
burning. The plot is clean cultivated with hand tools and used for the production of food
for the cultivator and his family; any surplus crops are sold for income. The plantation
tree seedlings are introduced into the agricultural crop at a stage when they will be
weeded for at least a year and should readily become established when the cultivator
abandons that area for food production and moves on to clear another taungya area.
Li parts of southeast Asia, traditional taungya is used extensively to create teak
plantations. In Thailand the system is associated with the establishment of forest
villages; whereas in the Solo water catchment area in Indonesia the growing of trees is
combined with a grass fodder. In Sierra Leone the cultivation of taungya agricultural
crops is limited to one year, and the trees are incorporated as soon as clearing is
completed. In the Kenya sharaba system, the cultivators were employed by the forest
department for nine men the or more per year*
In Ghana much of the heavy debris remaining on planting sites following selective
harvesting, manual clearing and broadcast burning of the tropical high forest is
utilized for charcoal production. Subsequent planting and tending is done manually.
(Courtesy D.A. Haroharik)
-10-
A variation of the traditional taungya system used extensively in Nigeria (where it
is called "farming for pay" or "direct taungya") and in Ghana (called "departmental taungya)
has the following main features (Olawoye, 1975) >
1) The fanners employed are recruited as wage- paid employees of
the forest department
2) Land hunger is not a prerequisite to taungya*
3) The forest department owns both the farm crop and the trees*
4) There is no allocation of individual farm plots*
Although there are many variations of the taungya system, incentives have much to
do with participation; the general inputs and benefits can be those as shown in the
following table*
Cultivators
Forest agency,
or government
Inputs
Labour (in return for the
use of land and for wages)
Land
Nanagement t tools and
equipment
Housing and services
Employment
Benefits
Income from employment
or incentives
Pood for family
Cash from sale of surplus
crops
Housing, services, educ-
ation facilities and
infrastructure
Reduced direct plantation
establishment costs
Long-term wood production
Reduction in shifting
cultivation
Not all of these factors apply to every case but they constitute a general outline.
For the landless shifting cultivators the provision of land for food production is one of
the main incentives influencing participation in taungya plantations*
The origins of the taungya system lay in the desire to displace harmful shifting
cultivation and to reduce forest plantation establishment costs* As a form of controlled
shifting cultivation, which minimizes damage to the soil by providing an effective tree
cover, the system does not cause the stress that too great a change in agricultural
practice could create for traditional cultivators* In the past, taungya has reduced the
cost of plantation establishment* More recently, some if not all, of these apparent
savings have been applied to forestry community development, as in Thailand and Kenya,
ensuring that the community is to some degree recompensed for its contributions to the
system* Traditional taungya may be considered an intermediate form of land use in the
development from shifting cultivation to either sedentery agriculture or full (forest)
employment, or possibly to a mixture of smallholding and part-time employment*
The intensive cropping of taungya pints reduces fertility of the soil, particularly
as additional fertilizer is seldom applied and the food crops are in competition with the
plantation trees* In Kenya, for example, trees grown in clean cultivation showed a 15$
better height growth than those in a maize sharaba and an 8% increase over those in a bean
sharaba (Kenya Forest Department, 19^7) In another region, Turbo, no comparative fall in
growth was recorded in fertilized maize*
-11-
MECHANIZATION AND MECHANIZED METHODS
Labour can do almost all of the work in establishing a forest plantation, and even
on a large scale oan be efficient and economic. In Brazil, for example, clearing of the
native forest was initially done by tractors, but high costs and low production led to the
use of manual methods and now nearly all the field operations are carried out by large
gangs of contract labour working under supervision of project authorities (Palmer, 1977).
In other areas, however, the sheer size and cost of the labour force required for large-
scale projects may preclude this as a realistic possibility. Mechanization, then, is an
important alternative.
Many of the site preparation operations described in the preceding sections can be
mechanized, and there is a range of machines and equipment available for such operations.
The main object of mechanization in plantations is to carry out selected operations
effectively and economically by employing machines. Where operations are done satisfact-
orily and economically by manual labour, and where there is a plentiful supply of suitable
labour, then only those operations beyond the capability of the labour and supervisory
services need be mechanized.
It is frequently suggested that mechanization reduces employment opportunities.
In comparing the relative merits of labour employment and mechanization, it is necessary
to balance social benefits against the cost benefits of using more efficient alternatives.
A soundly based, successful project, for example, whether mechanized or labour-intensive,
will in the long term provide more permanent direct employment, and additional indirect
employment in wood processing industries, than a non-viable undertaking. In general,
therefore, where mechanization of larger scale plantation projects reduces costs and is a
factor in project viability, it seldom results in jobs being lost but rather increases
employment possibilities within the economic criteria established by management and
planning.
Mechanization in the strict sense refers to the introduction of machines to
supplement manpower used in carrying out selected operations. In this publication the
term is used primarily to cover mobile engine powered units such as tractors, but it also
includes the use of chain saws and other handheld power units, the operation of which is
labour intensive. Use of draught animal power is treated separately.
Mechanization Principles
When mechanization is planned, there are certain basic principles which require
consideration and which apply not only to the land preparation phase but also to the
entire plantation rotation.
In selecting machines and implements for plantations, it is essential that
equipment should be fully suited to the operations required of it. It might, for example,
seem beneficial to purchase a machine or equipment which is capable of carrying out a
number of operations, but if such a compromise results in the selection of equipment not
completely suited to the critical task then its real usefulness may be at slight or at
most somewhat devalued. The concept underlines the need for trials to determine types
of equipment best suited to and most efficient for specified operations.
The planning of field operations should aim to maximize the effective use of
selected machines. In plantation layout and design, large blocks offer greater
possibilities of efficiency than small and diffused areas. The road and ride pattern
should allow ready access and turning space for mechanical equipment. To reduce the
proportion of unproductive turning time for tractors, the planned layout should allow
long tractor runs, preferably in two directions. Spacing is another critical factor
affecting the tree crops and equipment efficiency and offering a range of management
options requiring evaluation and judgement. For example, a spacing of less than 2.8 m
is seldom possible when normal agricultural tractors are used.
-12-
A major requirement is that every machine operator should be fully competent in
the operation of the machine or equipment in use. Poor driving and misuse of equipment
oommenly reduce tractor productivity by more than fifty percent. In many developing
countries where there is a shortage of skilled operators y training facilities are
necessary if the required levels of operating skill are to be attained. For trained
operators to maintain and improve their work, it is necessary to provide financial or
other incentives based on the serviceability and productivity of the equipment used.
Critically important in mechanization is the provision of an adequate repair
and service organization staffed by skilled personnel with an assured supply of spares
and replacements to ensure early and effective maintenance. As is the cause for operators,
in many parts of the world there is a need to provide training in repair and maintenance.
A machine is only of real value when it can perform its prescribed work efficiently.
Mechanization is a costly process, and its introduction requires a clear under-
standing that the objectives of the project are to be achieved efficiently and economic-
ally. For effective management 9 it is necessary to oost the various mechanized methods
or alternative methods of carrying out particular plantation operations. To maintain
the incentives for success, mechanized operations should be organized on as sound a
commercial base as possible.
In the early stages of plantation development , mechanization can and does occur
without full implementation of the main requirements discussed above but, of course, not
without creating problems and some loss in effectiveness. To commence large-scale
operations, however, without due consideration of the principles outlined can only lead
to the creation of an inefficient and uneconomic mechanized enterprize.
Advantages and Disadvantages of Mechanized Land Preparation
The main reasons for selectively mechanizing land clearing operations generally
concern the availability of labour, cost efficiency, scale of operation, timeliness of
operation and the quality of work performed.
Labour Availability
The absence or shortage of adequate labour can be a primary factor requiring the
introduction of mechanization. The optimum time for carrying out much of the land
preparation work is when soils are moist, and in many regions this coincides with the
period of maximum agricultural activity, with consequent local and seasonal labour
shortages. Again many of the land preparation activities entail heavy and arduous work
and the application of reO active mechanization eliminates the manual drudgery from such
tasks.
Cost Efficiency
In general, large-scale land clearing can be done with greater cost efficiency
by mechanized techniques than is possible by manual methods. A further factor,
particularly in developing countries, is the tendency for labour rates to increase at a
faster rate than machine costs, a trend which increases the comparative oost efficiency
of mechanized methods. Where there is large-scale unemployment, however, the application
of shadow costs for labour can indicate social oost benefits favouring labour intensive
methods.
-13-
Soale
Scale of operation is related to efficiency* There are no hard and fast rules as
to the level or scale at whioh mechanization should or may be introduced. For selected
projects all the relevant factors have to be studied and evaluated before any decision on
the possible timing and degree of mechanization is possible. In general, for larger scale
projects problems of control and productivity of labour tend to justify the introduction
of selective mechanization* The economics from increased usage of machines at the larger
scale further favour mechanized development.
Timeliness
In plantation development timeliness of operation is often critical; for example,
late land preparation can cause delays in subsequent operations, often with adverse effects
on both the plantation crop and on cost efficiency. Where labour or related elements
limit rates of production, mechanization with its generally fast work rates provides a
method of accelerating productivity and completing operations in timely fashion.
Quality
As a consequence of the considerable power and weight of machines, the quality of
mechanized land clearing tends to be superior to that of hand labour. Mechanized stumping
or knockdown generally removes a greater proportion of roots to a greater depth than
comparable manual operations. Similarly, plough or harrow cultivation is more effective
than cultivation by hoe.
Common constraints to mechanization in plantation development include:
1) difficult terrain where steepness, gullies or rooky outcrops
preclude the efficient use of machinesj
2) the high initial cost, often in foreign currency, of setting
up a mechanized operation, together with the high and rising
operating cost of fuels and oilsj
3) poor tractor serviceability due to lack of skilled personnel
to manage, operate and maintain equipment, often aggravated by
a) lack of spare parts,
b) bureaucratic delays in ordering or paying for parts
or services,
c) poor land clearance resulting in damage to cultiv-
ation equipment in subsequent operations and/or
d) lack of personnel incentives;
4) poor machine operation often resulting in unnecessary soil disturbance
or compaction detrimental to subsequent plant growth and
5) the opinion, often irrational, that mechanization causes redundancy
or loss of job opportunity.
-14-
Land Preparation Operations
This section is primarily concerned with mechanized methods for the removal or
destruction of vegetative cover and the cultivation of soils prior to planting or
seeding. In many parts of the world, particularly in areas with a marked dry season
such as in savannas, successful plantation establishment involves clean weeding in the
initial stages. Except on small areas or where taungya is possible, clean weeding
necessitates a considerable input of mechanized cultivation. To allow efficient
mechanized weeding, land should be free of all surface woody vegetation and of all roots
and stumps to the maximum depth of penetration of the weeding implements, which requires
the stumping of all standing trees and the disposal of all stumps, roots and other woody
debris from the site.
The main operations are:
1) felling or stumping of natural woody vegetation by knockdown,
2) windr owing,
3) cleaning up,
4) burning or disposal of debris,
5) laying out and
6) pre-planting cultivation.
Operations 1 to 4 presuppose a natural woody vegetative cover which has to be
removed or destroyed before plantation development can proceed. On grassland sites
development would be initiated at operations 4 f 5 or 6, with burning, when used, confined
to eliminating the grass cover in the dry season prior to planting. Gleaning up,
burning and laying out are generally manual operations, although some supplementary
mechanized inputs may be required.
Removal of Natural Woody Cover
There is a considerable range of mechanized land clearing techniques; the main
methods are adapted to the type and density of vegetation, topography, climate and
subsequent establishment techniques. In areas where no mechanized weeding is planned,
for example, the removal of roots is optional, and trees can be felled at or above ground
level. Where harrow weeding is intended, however, in addition to all woody vegetation,
roots and stumps should be cleared to the maximum depth of cultivation. Vegetation density
is important in that the heavier the tree cover the greater the power necessary to remove
it. It follows, therefore, that equipment and techniques will vary over a range of
vegetation types such as thicket, woodland or rainforest. Slope and terrain place some
limit both on what may safely be cleared and how the selected technique will be applied.
Rainfall also affects many facets of clearing, but is most critical to the timing of
operations. It is recommended that clearing take place only when soils are moist
because roots are extracted freely under such conditions and because at this time tree
stems are full of sap and are less liable to breakage.
Felling without Root Extraction
Mechanized cutting employs crawler tractors with front-end mounted sharp blades
to out and fell trees at or near ground level. An angled and sharpened K.O. blade is
suitable for shearing thioket or woodland trees up to 30 cm diameter or larger; the
V-shaped blade is suitable for larger forest trees.
-15-
On smaller areas or on gradients where tractors oannot be used, trees may be felled
using a range of ohain saws; for brush or thickets a portable scrub cutter is useful.
This is a small circular saw at the end of a metal rod f powered by a small back-carried
petrol motor.
In the U.S.A. brush or thioket growth is extensively felled using heavy rolling
choppers, which comprise a large drum with cutting blades towed by a orawler tractor. They
out the woody vegetation into small pieces and incorporate the debris into the soil. There
is a range of makes and types of choppers from small to very large single drum types to
multiple-drums pulled in tandem. The cutting and crushing effect can be increased by
filling the drum with water. In general, unless a speed of about 8 km/hr or more is
maintained, the drums roll over the vegetation and give inadequate chopping. To maintain
speed, a direct -drive power unit is required.
The light-weight 4 ton model chopper filled with water requires a 35 to 60 drawbar
horsepower and is effective on woody stems up to 5 om diameter. The 8 ton model requires a
50 to 75 hp drawbar pull and is effective on brush to 8 om diameter. The 11 ton model
requires 70 to 125 hp drawbar and is effective in chopping hardwood brush up to 10 om
diameter. Even larger models to 16 ton requiring a 250 hp drawbar pull are available for
dense brush and extensive areas. The size of chopper needed for a particular job is
determined largely by the density and size of the hardwood scrub species. In trials on
sandy soils in southeastern U.S.A. (Burns and Hebb, 1972) it was found that the 11 ton
model was more effective than either of the lighter types and that it killed more
hardwoods of all sizes and resulted in higher survival of the planted pines. These trials
were limited and did not include choppers of greater weight than 16 tons.
Fleco Corporation (1968) gives the following estimates of chopping productivity:
Clearing Unit Output in ha per hour
385 FWHP !/ + 16 ft (4.9 m) chopper 1.5 to 4.1
216 DBHP -/ + 14 ft (4.3 m) chopper 1.3 to 2.3
52 DBHP + 7 ft (2.1 m) chopper 0.7 to 1.4
A single chopping treatment does not provide sufficient control of hardwoods,
regardless of the size or weight of equipment used. Sprouts develop at the root collar
and this requires a second operation. This applies to all tree cutting operations, and
unless there is a subsequent effort to kill the stumps, coppice or sucker regrowth will
occur and the woody cover will quickly re-establish itself.
In Turkey, an Australian made "tritter 11 or "land conditioner 11 was used to macerate
maquis scrub ( Querous o OOP if era, Arbutujg ujneclo and ISrioa spp. ) of up to 8 cm diameter
(Deveria, 1977)T The tritter is a towed scrub clearing machine of varying widths; that
tested in Turkey was 1.58 m wide. It is driven from the power take-off of the towing
tractor by V-belts and requires a 100 hp rated gear box and a speed reduction box. The
machine breaks up the woody vegetation by the action of a flailing hammer, leaving a
mulch of chopped vegetation on the soil. Performance depends on vegetation size and
density and the forward speed of the tractor, the size of material it can deal with is
inversely proportional to the speed. For typical maquis in Turkey an average clearing
rate of 0.28 ha/hr was achieved.
J/ FWHP Flywheel horsepower
2/ DBHP = Drawbar horsepower
-16-
A County 4x4 wheel-tractor with rear-mounted tritter IB used in Turkey to
pulverize maquis in preparation for ploughing. A banksman keeps watch for
boulders. (Courtesy ENQ. Cooling)
Removal where Roots are Extracted
In mechanized stumping or knockdown f crawler tractors and matching equipment are
used to push or pull over standing trees while extracting the roots in the same operation.
A main objective in these mechanized operations is to minimize soil disturbance;
therefore none of the techniques incorporate digging or scraping.
1. Single tractor techniques
One of the better units for knockdown is a crawler tractor with a front-
mounted application rake with top pusher bar. In woodland, for example, the tractor
makes a pass at a standing tree by applying the pusher bar as high on the bole as it will
reach and pushes the tree over. The rake is then lowered and applied to the exposed root
system; the roots and main laterals are ripped out of the ground and the tree may be
pushed for windrowing. The tractor then reverses before advancing to the next tree where
the operation is repeated. Where a larger tree will not readily yield to the pusher, rear
mounted rippers are lowered into the soil and the tree is circled to out lateral roots.
Such a tree is then usually fairly easily pushed over.
-17-
The front -mounted rake is suitable for light clearing and windrowing. In Turkey it
is attached to the C-frame of a tractor and is used for clearing and piling degraded
oak coppice and similar vegetation of small diameter and large root mass.
(Courtesy E.N.G. Cooling)
The system may be adapted for heavy or rain forest vegetation by carrying out the
work in two phases. First, a tractor fitted with an angled blade (a K.G, blade without
the knife edge is satisfactory) and hydraulic tilt rams advances through the forest
pushing over all undergrowth and small trees. Following this, when visibility has been
improved, a tractor fitted with a tree stinger advances through the area and pushes over
all the remaining large trees* In practice, the work is usually carried out by two
tractors working around the forest in circular fashion. The tractors operate individually,
with the understory clearing tractor usually at least 100 m in advance of the tree pushing
tractor,
A crawler tractor fitted with a hydraulioally operated bulldozer was
previously the most commonly used machine for clearing scrub. Although still used,
especially in small areas, the bulldozer is considerably less efficient for clearing than
a pusher and rake* In most thicket or brush a heavy duty clearing or grubbing rake is a
better attachment for readily extracting roots and stems.
-18-
A crawler tractor fitted with a tree stinger can be used to push over trees in
woodland or rain forest which are too large for efficient clearing with chaining
units or more conventional bulldozer or angledozer blades. (Courtesy T.G. Allan)
2. Chaining techniques
Chaining employe two crawler tractors with front -mounted blades or rakes and
between them a rearhitched heavy 9^ m or longer anchor chain. In areas with larger or
strong rooting trees, it is necessary to have additional or follow-up tractors fitted
with a tree stinger to push over any tree holding up chaining progress.
In woodland the two crawler tractors advance at the same steady speed some 15 to
25 m apart dragging the chain behind. The distance apart varies with the density of the
trees; the greater the density the closer the tractors have to operate. The outer tractor
travels along the outside of the uncleared bush, and the inner tractor, 15 to 25 m inside
the bush f advances parallel to the outer tractor and in as straight a line as possible. It
is important that the tractor operators are able to see one another and that the outer
driver maintains the same speed as that of the inner. The tractors advance at a reasonable
speed and the trailed loop of the chain progresses in a meandering fashion seldom striking
more than two trees at one time and putting little strain on the tractors. It is essential
to keep the chain moving over the ground at a reasonable pace as it is impact which knocks
over the trees and thereby loosens and extracts the root system. The chain generally rolls
freely over knocked-down trees. As the trees are knocked down, the main root system and
laterals are extracted at the same time. In larger trees, the lateral roots extending in
the direction of fall are only partially extracted, but such soil embedded roots are usually
ripped out at windrowing. If no windrowing is prescribed, back chaining may further extract
such roots.
-19-
An efficient unit for large-scale clearing of savanna woodland comprises two standard
D-8 tract ore, fitted with protective canopy, which pull a heavy anchor chain at least
90 m long. A third tractor fitted with a tree stinger assists in pushing over large
trees. (Courtesy T.G. Allan)
Anchor chains are fitted with heavy swivels near the towing tractors to prevent
chain from kinking. (Courtesy T.G. Allan)
-20-
Traotor runs should be as long aa possible, as turning time is largely unproductive.
At the end of eaoh run, the tractor unit is turned to return on a swath immediately adjacent
to the previous run. In the turning process, the tractors reverse inner and outer positions
giving an equable share of work to the tractor operators in that the inner station is
generally the more difficult to operate.
Chaining is bert auited for large-scale clearing of woodland or savanna type
vegetation cover. It is not suitable for some types of thicket, however, where the trees
tend to bend under the chain making extraction difficult; nor can it be used in dense
for eat or rain forest because visibility in so poor as to preclude the teamwork necessary
for successful operation.
The ohain size depends on the tractor power available and the type of vegetation,
but the length should be at least two and a half times the height of the tallest trees.
A 5 om stud link 90 m long and weighing about 500 kg is suitable for light woodland.
Heavier ouains are available for heavier bush types.
Special Conditions
Areas covered with a coppice, shrub or thicket with full root systems below ground
are often found near centres of population where forests have been felled for firewood.
Such areas may be stumped manually or mechanically using a crawler tractor and rear-
mounted root plough. The root plough is a V-shaped cutting blade which when drawn
laterally through the soil floats at a predetermined depth and effectively severs all
roots encountered. Behind a 180 hp crawler tractor the implement effectively operates at
a depth of up to 42 cm. Vanes bring the severed roots to the surface with minimum soil
disturbance. Providing the cutting edge is kept sharp, this is a most effective stumping
and subsoil ing tool. It can readily be used for clearing stumps from logged over areas.
A crawler tractor with rear-mounted root plough is effective in clearing
with extensive root systems. The plough is set into the soil at a predetermined
depth where it severs the roots, which are then forced to the surface by special
vanes. (Courtesy T.G. Allan)
-21-
Windrowing
Following knockdown, it is necessary to dispose of the felled debris whioh litters
the area. The same orawler tractors whioh were used for knockdown oan be readily fitted
with front-mounted rakes for mechanized windrowing and under some conditions heavy wheeled
tractors may be used. On level terrain the heaps may be linear and parallel, while on
slopes they may be sited on the contour. Windrowing may be done at any time during the
year. In woodland it is convenient to site windrows 50 m apart. In this operation the
front-end rake is lowered to ground level and all debris over a pass 25 m long and at
right angles to the windrow is pushed onto the heap. The tractor then reverses 25 m and
tne raking process is repeated. This pushing of debris is then repeated from the other
side of the windrow, leaving some 50 rn between linear heaps. It is important to pack the
windrows tightly and to include as little soil as possible. To allow access, 5 m gaps
Bhould be left in the windrows at 100 to 200 m intervals. In heavy forest with extensive
debris, windrows might be only 25 m apart.
An alternative method of windrowing is to pile the debris around felled larger
trees. Thin gives an irregular pattern of heaps and tends to take marginally longer than
linear windrowing.
The general equipment for windrowing is a heavy track or wheel tractor, preferably
with power-shift control and with a front-mounted rake. The reinforced teeth of the i^ake
are set into the soil and in pushing forward most surface and some sub-surface woody
vegetation is picked up while most of the soil falls between the rake teeth or tines, but
even with careful operation, some topsoil is swept up with the woody debris and IB
dpnor.ited in or near the windrows.
A front-end rake mounted to a crawler tractor is used in the Ivory Coast to windrow
rain forest debris following knockdown. (Courtesy T.G. Allan)
-22-
This frontmounted rake is a useful attachment for removing rocks and roots and
for piling heavy brush. (Courtesy T,Q. Allan)
Gleaning Up
No matter how well knockdown and windrowing have been carried out, there IB usually
some debris or stumps remaining in the cleared area. Stumps left in the ground should be
pegged or marked* Where there is not a great deal to clean up the usual practice is to use
manual labour to gather the residual debris and put it in heaps or windrows and to deal
likewise with any stumps it is necessary to excavate. Where there is extensive cleaning
up, the operation may be mechanized using crawler tractors with rear or front mounted
stump extractors or rakes. If there are holes where stumps have been excavated, these
require filling and levelling.
Burning of Windrows
When windrows or heaps have dried out, they should be burnt when conditions are
suitable. The aim should be to burn as late in the dry season as possible. This may recniire
protecting the heaps from incomplete, accidental burning earlier in the dry season. In
rain forest areas where dry periods are short, it may be necessary to supplement or
intensify the burn with oil fuel, and even then it may prove difficult to obtain a
satisfactory total burn. The object is to have as fierce a fire as possible, and for this
burning should take place during the day, preferably when there is a wind. The fire should
be lit on the windward side of the windrow, where it will develop its own draught. When
burning is incomplete it is advisable to have a crawler tractor with mounted rake standing
by for repiling. When the fire has lost its main intensity, smouldering logs and stumps
should be repiled to maintain the concentration of heat and combustible material.
-23-
Land Clearing Produotivity and Choice of Equipment
Produotivity data forms the basis of planning and selection of land clearing
methods. Any general rate or cost of land clearing per hectare is of little value unless
it is related to vegetation density and tractor power. Basal area of woody plants
expressed as m^/ha gives a reasonable assessment of forest density (although a factor may
have to be applied for major height differences). Work in Nigeria (Allan, 1977) shows
that:
r\
1) in light savanna of 9 m /ha basal area, chaining productivity was
5.5 ha/hr for a clearing unit consisting of two 180 hp tractors;
single tractor knockdown and windrowing using a 65 hp crawler
tractor were 0,48 ha/hr and 0.49 ha/hr respectively; while hand-
stumping and piling employed 69 man-days and 63 man-days/ha
respectively;
2) in heavier savanna of 13 m /ha basal area, chaining productivity
was 2.8 ha/hr using a clearing unit consisting of three 180 hp
tractors (two for chaining and one for follow-up knockdown with
a stinger); windrowing using a 180 hp crawler was 0.57 ha/hr while
hand stumping and piling employed 134 man-days and 99 man-days/ha
respectively.
This gives an indication of the range of productivities and of the type of options
open to management. Translating these productivities into costs and taking manual
operations as 100$, chaining costs in Nigerian savanna are of the order of 5%, single
tractor knockdown around 10^ and mechanized windrowing less than 12$>. Similar data may be
determined by trial for any plantation project. In Brazilian cerrado, the productivity of
a chaining unit consisting of two 160 hp crawler tractors varied with woodland density
from 0.5 to ft ha/hr (Terencio da Silva and Lourenco, 1977).
In rain forest in the Ivory Coast, the average tractor hours/ha for clearing
using 180 to 220 hp heavy crawler tractors was 8 to 12; the lower figure was apportioned
as 3 hours knockdown, 3 hours windowing and 2 hours cleaning up (Allan, 1973&). No basal
area figures were available*
In selecting methods of land clearing, the management options are manual, single
tractor technique, chaining or a combination of these techniques. If one of the major
objectives of the project is employment, then all of the clearing operations could be
manua] , whereas if minimizing cost is considered critical then mechanization may be
preferred. Unfortunately, deciding among the options available is seldom as simple or
clear cut as this. The first requirement is to determine the availability of resources.
In relation to labour, are the required numbers available as and when required? For
mechanized operations some of the essential considerations are:
past experience in mechanized work;
2) availability of equipment in the area or locality;
3) efficiency of the available equipment for the required operations;
4) availability of operators of the required skill and
5) existence of the required infrastructure, or possibility of
establishing it readily.
-24-
Deoisions require looal data and looal information. Scale of operation will
greatly affeot selection. Small-scale projects are most readily dealt with by manual
clearing, while for large-scale projects mechanization is usually more economic and
efficient. Small-scale projects usually do not lend themselves to mechanization because
they do not allow for tractors to be operated for long enough periods to be cost efficient.
For example , in general a mechanized land clearing unit can only be justified if the
individual tractors can operate somewhere in the region of 1 250 hours or more per annum.
Although there are no hard and fast rules relative to scale, something of the order of
4 000 ha/annum on a sustained basis would certainly constitute large scale* Such a
programme could well be made up of a number of smaller areas or projects, or of combined
forestry and agricultural programmes.
A chaining unit consisting of four 180 hp tractors and equipped with chain, rakes,
tree stingers, root ploughs and other necessary equipment could deal with the following
annual scale of work:
1) knockdown - 4 000 to 6 000 ha during a 4 months wet season;
2) windrow - 5 000 to 6 000 ha during a 6 months dry season and
3) major overhaul, maintenance and repairs - 2 months.
Any time not used as above could be used for cultivation, road making or other capital
works.
Concerning selection of equipment, there is a considerable range of crawler
tractors; the essential is to choose that model or models best suited to the planned
operations. Land clearing can be dangerous and all tractors should have heavy duty cabs
and other protection features. In the bush, bees and other insects can cause problems
and protection against them may be required.
The main tractor attachments for land clearing are as follows:
tree stinger, root plough,
front-end rake, anchor chain,
combined rake and pusher bar or tree boom, rolling chopper,
bulldozer blade, stumpers,
KG blade, towed root rake,
V-type blade, land conditioner.
rippers,
Selection of tractors and matching equipment is an important management decision.
The careful matching of machines and equipment to local conditions, for example, can easily
effect savings of more than 50$ of total mechanization costs, as compared to the use of less
suited or poorly matched machinery.
Serviceability is also a principal criterion, and that looal agency providing the
better back-up service and supply of spares should be given preferential consideration.
All attachments must be matched to the power units held. As there is a considerable range
of equipment, specifications need to be carefully compiled and it is often advisable to
obtain specialist advice*
Plant Cation Layout
Laying out is an operation in which compartments, blocks, roads, rides and fire-
breaks are surveyed and delineated on the ground. As the design of plantation layout is
a major planning consideration it is also discussed in Chapter 6. The main mechanized
aspects of the operation are the cultivation of firebreaks and the formation, draining and
-25-
paving of roads. Firebreaks are readily cultivated using the same orawler tractors and
heavy offset diso harrow ploughs ae for pioneer ploughing. The land clearing orawler
tractors with bulldozer blades can be used for putting in road lines and outs, and such
lines when provided with bridges and culverts will serve as class 3 roads or planting
tracks. Road formation and the provision of all-weather surfacing of the higher
specification class 1 and 2 roads will require additional mechanization in the form of
road graders, front-end loaders and tipper trucks. More complete notes on the establishment
of plantation roads are given in Appendix B.
Mechanized Pre-planting Cultivation
The main purpose of removing roots and woody debris from selected sites is to
allow soil cultivation before and after planting. Such clearing and cultivation creates
site conditions particularly favourable to the plantation tree crop by eliminating or
reducing vegetative competition and by increasing percolation, which can reduce the
moisture loss from the soil. These favourable water budget features are particularly
important in areas of restricted or seasonal rainfall. The need to reduce competition
applies also on certain dense or tall grassland sites where failure to cultivate results
in inadequate plantation establishment.
Cultivation may be partial as in strip cultivation and ridge ploughing, total as
in clean cultivation or supplementary as in ripping or subsoiling.
Strip Cultivation
Under certain site conditions where some species require only local weeding to
allow adequate growth and development, it may be enough to cultivate only a narrow band
(1 to 2 m wide) along the planting line, sufficient to give the trees freedom from
competition in the initial period after planting. Often this can be achieved by the
harrowing effect of a mechanical tree planting machine (see for example page 63). The
planting stock used in these conditions must be vigorous. Where necessary, further
cultivation would take the form of a supplementary manual operation. Strip cultivation
by opening up only a part of the cite may be of particular importance where there is a
high risk of erosion.
Strip oloughing along contour lines in gentle terrain is used extensively in
establishing Firms patula on the Viphya Plateau in Malawi. A reversible 3-disc plough
drawn by a 70 hp wheeled tractor is used to breakup the short montane grass cover.
Initial cultivation is to depths of less than 30 cm; a subsequent harrowing improves
the soil tilth. On shallower soils over an indurated, weathered quartzite layer, where
plough penetration is slight, subsoiling in the direction of the planting line is
necessary. On sites free from stones, a 1.55 ro wide rotavator is sometimes used, which
can cultivate to 12.5 cm depth provided grass is previously burnt off. Mattock pitting
is necessary on rougher and steeper sites, but records show that it is almost twice as
costly as strip ploughing.
Ridge ploughing is used extensively in the United Kingdom and other upland
temperate areas, particularly on wet soils and peatland bogs. A specialized mould-board
plough, generally drawn by a heavy crawler tractor, is used to turn over a broad turf
ridge creating a clean deep furrow which helps to drain the site. On difficult sites
where the peat is deep, the furrows are spaced at intervals of 1.5 to 1.8 m. On better,
less wet sites, furrows are spaced at 50 to 6.5 m apart. The turves are then manually
out into squares which are laid out at the required plant spacing. At planting, tree
seedlings are planted into the turves.
-26-
Qrassland sites of gentle terrain on the Viphya Plateau in Malawi are prepared
for planting by ploughing contour strips 1*2 m wide with a mechanical disc plough.
(Courtesy D.A. Haroharik)
Drainage of heavy wet sites in the United Kingdom oan be improved by ploughing with
a mould-board plough. That shown here is used with a standard parkgate oarriage
towed by a Fiat 100 o tractor. ( Courtesy D.A. Thompson)
-27-
On drier moorland sites, especially Calluna heath landB f the problem is to reduoe
shrub competition and soil compaction and to break the hardpan when present. Single
farrows are made at the required plant spacing using either single mould-board plough
or a speoial tine plough. At planting, seedlings are notched either into the furrow
bottom or into the side of the furrow and ridge.
Clean Cultivation
Clean cultivation of the site prior to planting is required where subsequent
weeding is to be done mechanically. The practice is common, for example, in regions with
a long dry season where clean weeding is necessary in order to prevent grass from
competing excessively with the tree crop for limited soil moisture. Clean cultivation
often comprises two main operations: 1) pioneer ploughing and 2) pre-planting harrowing.
1* Pioneer ploughing
The objective of pioneer ploughing is to break in the soil for the first
time and plough in all weeds or vegetation. This is essentially a rough operation and
the cultivation need not be to the same precision or standard as is required for
agriculture. The ploughing should generally be done when the soil is moist but not
saturated and to a depth in excess of that reached by lighter implements used in
subsequent weeding operations; over 20 cm is usually required. Penetration is often
difficult in dry soils.
The operation may be effectively done by a crawler tractor with a matched heavy
duty disc harrow plough having heavy steel discs of over 75 cm diameter. This offset
harrow plough gives a deep penetration of over 30 cm under ideal conditions and, although
it is a harrowing rather than a plough action, in practice has given adequate results for
subsequent plantation operations. Although these heavy duty harrows are sufficiently
strong to shatter most stumps, and can therefore be used to plough unstumped land, such
rough operation is likely to reduce the life of the equipment and increase the cost of
operation.
The heavy duty offset disc harrow plough towed by a crawler tractor is used for
pioneer ploughing. (Courtesy TG, Allan)
-28-
Pioneer ploughing oan also be undertaken by a medium wheeled tractor with a mounted
disc plough. The oultivation is good, but generally to a shallower depth than the harrow
plough. On difficult Bites, the diso plough ia leas robust than the heavy harrow.
On sloping ground in Turkey, the Clark double mouldboard tine plough is used for
pioneer ploughing on the contour (Deveria, 1977). This subs oil ing plough produces a mound
and furrow effect, with a downside mound approximately 1.5 wide and 0.5 m high and the
upside trench 0.3 m deep and 0.5 m wide. The trench has a sub soil ing groove extending for
a further 0.3 m depth.
2. Pre-planting harrowing
Pre-planting harrowing usually takes place just prior to planting. The
objective is to breakup soil olods and create a tilth, to level the soil surface, to bury
any weed growth and to have the land in a clean state for planting. Land free of weeds,
with friable soil cultivated to at least 15 om considerably facilitates planting and
subsequent mechanized weeding. The operation is generally undertaken by a medium wheeled
tractor with a mounted agricultural type diso harrow. The operation should be in the same
direction as ploughing. If justified by the quantity of work, a wide heavy duty diso
harrow may be used specifically for this work, or alternatively, fuller use may be made of
smaller weeding harrows. Cultivation may also be done by a rotavator, or rotary hoe, but
this implement requires greater skill to operate. There are also a number of large heavy
harrows that may be used with crawler tractors, but implements such as the pulverizing
harrow produce so fine a tilth that great care is required in their use, particularly in
areas liable to erosion.
Following ploughing, tilth oan be improved by pre-planting harrowing with an
offset diso harrow. A wheeled tractor is a suitable power unit for this
operation. (Courtesy T.O. Allan)
-29-
In parts of the southeastern United States and other areas where there is a high
water table during much of the year, bedding, or mounding, of the planting sites facilitates
planting and results in better tree growth by improving drainage and miorosite environment.
The operation is done with a disc bedding harrow designed to oonoentrate surface soil,
litter and vegetative debris into raised beds 15 - 30 om high and about 1.2m wide at the
base. A rolling hourglass-shaped drum with a centre-mounted coulter is often used behind
the harrow to shape and pack the bed. The site must be sufficiently free from logging
debris and vegetation for a well-shaped bed to be formed. Beds should be oriented so as
to channel runoff into ditches and natural water courses and, except in flat terrain, they
should follow the contour. The operation is not suitable where seedlings would suffer from
seasonal drought (Raines et, al. t 1975 and Balraer t al. t 1976).
or Ripping
On shallow soils overlying weathered rock, on compacted soils or on soils with an
underlying hardpan where root growth is restricted, water infiltration and root penetration
can often be improved by subsoiling, or ripping. The operation involves tillage of the
subsurface soil, without inversion, by subsoiling tines or rippers mounted behind wheeled
or crawler tractors. Subsoilers can be either of the single-tooth or multiple-tooth type.
With the appropriate tractor and equipment, subsoiling to depths in excess of one metre
is possible, but shallower operation to about 60 - 70 cm is more common. Subsoiling
usually follows normal ploughing, and on sloping land it should be done along the contour.
In Cuba (Masson, 1973) it was found that subsoiling in the dry season gave much better
lateral shattering than when carried out in wet soil and that the general effect was
highly beneficial to subsemient planting.
Indurated soil layers can be broken by subsoiling to improve water infiltration and
seedling root penetration. The soil surface is not turned. (Courtesy T.O. Allan)
-30-
ourfaep drainage arid microsite conditions can be improved by uKing a bedding harrow
and roller to form raised beds for planting (Courtesy T.G. Allan)
-31-
OuJLtivation Productivity and Choice of Equipment
Recorded practical data on ploughing and harrowing indicate productivities of the
following orders
Operation and Equipment
Ploughing
65 hp wheeled tractor with mounted
3 disc plough
80 - 100 hp crawler tractor with
matched heavy duty harrow plough
Pre-planting harrowing
65 hp wheeled tractor with 2 m
disc harrow
65 hp wheeled tractor with 3 m
disc harrow
80 - 100 hp crawler tractor with
pulverizing harrow
Output in ha/hr
Tropical I/
0.35 to 0.40
0.5 to 0.75
0.5 to 0.9
0.9 to 1.1
1.0 to 1.2
Temperate
0.46 to 0.56
1.0 to 1.2
1.1 to 1.7
J/ Figures for the tropics are based on practical field trials in east and
west Africa.
2/ Figures for temperate regions are based on Culpin(l975) for agricultural
land.
Note: Productivity is a factor of so many variables such as state of
equipment f operator effioiency f soil type and condition that
figures quoted are only indicative. Tropical outputs tend to
be less because they refer to pioneer operations under rough
conditions whereas the temperate figures are based on agri-
cultural practice.
There is an extensive range of tractors and cultivation implements adequate for
plantation cultivation; the main choice is between wheeled or crawler units. In relation
to ploughing, wheeled tractor units tend to be marginally more cost efficient, but heavy
duty crawler unite cultivate to greater depths and eradicate hidden roots and other movable
obstructions. As for land clearing equipment y decisions on cultivation equipment should be
based on local experience and knowledge and where there are gape, data may be obtained from
trials or from projects operating under similar conditions.
If timeliness is considered the main factor in pre-planting cultivation, then those
units giving the greatest productivity should be preferred* Efficiency and usage can be
important 9 however, and it may be possible to reduce costs by fuller use of heavy clearing
equipment in cultivation or by increasing the use of wheeled tractor weeding units in the
cultivation phase*
-32-
Seguenoe of Land Preparation Operations
As already noted, olimate considerably affects land preparation operations* The
following is an outline sequence of operations for an area with a 6-month dry season,
assuming that land cleared during one wet season will be planted at the beginning of the
next. The sequence can be adapted to other climatic patterns and may even be extended over
two years | but any longer period runs into regrowth or weed problems.
Season
Start of rains (after 100 mm
recorded) , year
20 days after end of rains,
year
Before end of dry season, year
Beginning of rains, year 1
Start of rains (after 100 mm
recorded) , year 1
Operation
Commence knockdown or stumping.
Windrowing, cleaning^-up and
ploughing between windrows may
also start*
Stop knockdown or stumping.
Complete windrowing.
Clean-up between windrows.
Burn-off windrows.
Complete ploughing.
Harrow prior to planting.
Commence planting.
Commence knockdown and ploughing
for year 2 planting area.
DRAUGHT ANIMALS
For small-scale plantations in light soils, trials in northern Nigeria employing
oxen with matched ploughs and spring tine harrows have indicated that such units can be
operated practically and economically for pioneer ploughing and pre-planting harrowing
(Allan, 1973b). Such units require a large training input, however, and are seldom used
in forestry.
Cultivation using oxen with matched ploughs and spring tine harrows is a feasible and
economic possibility for small-scale plantation development on selected sites.
(Courtesy T0. Allan)
-33-
CHEMICAL METHODS
The main use of chemicals in site preparation is to kill grass, shrubs, trees or
stumps* Under certain conditions ohemioal application alone may give adequate site
preparation, but more frequently chemical s are used in oon junction with or supplementary
to other land clearing techniques. Areas of grass, for example, may be killed by
herbicides so that it can be burnt off while surrounding vegetation remains green.
Chemicals may also be used to kill regrowth following felling, stumping or chopping.
In addition to their use in site preparation, chemicals are also widely used to
control weeds during plantation establishment. For post-planting weeding it is important
to apply the chemical in such a way and at such a season as to minimize the risk of damage
to the plantation trees.
Various terms are used to refer to the chemicals used in site preparation and
tending. A "phytooide" is a general term for any chemical preparation used to kill or
inhibit the growth of plants. It includes "arboricides", "silvioides" and brushkillers,
which are used against trees and other woody plants, "herbicides", which strictly speaking
are used against herbs, and "fungicides", which axe directed against fungi. The term
herbicide, however, is now in common usage to refer to all chemical substances used for
killing plants, especially weeds, regardless of whether they are herbaceous or woody, and
is used in this sense in this publication.
Herbicides are usually marketed under proprietory names, and the same chemical
compound may have different names in different parts of the world. Some are toxic to all
vegetation while others are selective, for example, affecting only dicotyledonous plants,
only grasses, or only certain genera.
Herbicides act in the following ways in killing plants!
1) The "contact" herbicides poison the parts of the plants coming in
contact with the ohemioal.
2) The "translooation" chemicals are absorbed either through roots,
foliage or stems and are translocated via the xylem or phloem.
3) The "soil acting" or pre-emergenoe chemicals are toxic in the
soil to germinating seeds.
4) The "total" weedkillers, like sodium chlorate, kill all vegetation
when applied to the soil. The soil remains poisoned for several
months after application.
The effectiveness of herbicides is dependent on a number of variables such as
season of application, plant species and size, forest structure, soil moisture and weather.
Herbicide applications made during the growing season are generally more successful. Late
spring or early summer when root reserves are low are particularly favourable periods. In
general, large trees are harder to kill than small ones, and the more vigorous the tree
the more difficult it is to kill. Trees under one year old are particularly susceptible
to herbicides. Forest stands of two or more levels will require either two different
treatments or two applications of the same treatment, and particularly dense stands may
preclude the successful use of herbicides. Soil moisture has an effect on the success of
translocated herbicides. Although a low or deficient supply of soil water does not affect
absorption, it can hinder translooation in hardwoods. Rainfall can have adverse effects
by washing off sprays from bark and foliage, and high winds make broadcast applications
ineffective or spotty. Moderately warm temperatures and high humidity are considered
favourable conditions for spraying, but high temperatures can physically effect the
herbicide, as even low volatile esters start to volatilize above 32C. These represent
only a few of the possible variants affecting herbicide application.
-34-
In some countries considerable work has been done on the types and uses of
herbicides, and rates and methods of application can be laid down for specific vegetative
types. In many other areas work is at the experimental stage and much remains to be done
in developing optimum and safe techniques. As a consequence of the many variables in
herbicide application and the toxio side-effects of many of the chemicals, there is an
obvious need for detailed study and research before applying such techniques in new areas*
A useful "Review of the Eoologioal Effect of Herbicide Usage in Forestry 49 has been compiled
by Kimmins (1975) which contains an extensive list of references.
Principal Herbicides Used in Forestry
The following sections give a summary description of the main herbicides whioh
have found application in forestry. The list is far from complete? for a more
comprehensive account of the type of herbicides and more detailed information on their
use f the reader should consult one of many weed control handbooks, such as Crafts (l975)t
Fryer and Evans (1970) and Fryer and Makepeace (1972).
Herbicides for the Control of Woody and Herbaceous Weeds
(2 f 4t5-triohlorophenoxyaoetio aoid)
This is a translooation herbicide, particularly effective against woody broadleaved
species. Most oonifers are resistant in the dormant season, but some species such as the
larches and some pines (e.g. Pinus radiata) are susceptible.
Various forme of 2,4,5-T are available; most common are the! 1) amine salts, 2)
unformulated esters and 3) formulated or emulsifiable esters)* The amines come in liquid
form and are available as either water or oil soluble for foliar spraying. The unform-
ulated esters are suitable for use only in oil (itself toxio to trees) whioh restricts
their use to the control of vegetation before the forest orop is planted, or to
applications to stumps, stems and frill girdles. The formulated or emulsifiable 2,4 f 5-T
esters are prepared for emulsifioation in water. These are normally diluted in water for
spraying and, though more expensive, have a more widespread use.
Most of the common broadleaved woody species, in all climatic regions, are
susceptible to 2,4, 5-T foliar spraying, some more than others, and this has become one of
the most widely tried and used herbicides. In the temperate zones, the genera most
susceptible are Alnus, Aesoulus, Acer, Be tula, Corylus, Garpinus, Populus, Prunus, Salix,
Sambuous and Ulex. Resistant genera are Ilex, Ligustrum and Rhododendron. Onerous spp. f
though partially resistan u to foliar sprays, oan be controlled by bark spraying. Often
a related phenoxy herbicide called silvex 2(2 f 4 f 5-triohlorophenoxy) propionio aoid, is
more effective than 2,4,5-T in controlling certain woody plants, particularly oaks.
In the United States 2,4 f 5-T has been used extensively for site preparation and
for weeding. Rates of application are in the order oft
Method Application Rate
Foliage sprays 2.5 to 5.0 kg aoid equivalent (a.e.)
per ha
Shoot sprays 5 to 7.5 kg a.e. per ha
Basal bark and out 6 to 8 kg sue. per 450 litre of
stump treatments oil
In Australia 2 f 4 f 5-T has been reported as effective in controlling euoalypt ooppioe
regrowth in pine plantations.
-35-
-D (24-diohlorophenaryaoetio aoid)
This is a translooation herbicide useful for the control of a wide variety of
broadleaved herbaceous weeds. It is available in the same forms as 2 f 4 f 5-T. In forestry,
2,4-D has found a particular use in eliminating heathers (e.g. species of Gallon a. Erica
and Rubus) . For this purpose, the low volatile monyl ester of 2,4-D containing 500 g aoid
per litre is suitable; prepared for emulsifioation in water it can be used as a foliar
spray. Young conifer plants are susceptible to damage by 2 f 4-D in the growing season.
The amine salt formulation is used undiluted for application to outs made in the bark of
trees*
The combination of 2,4-D and 2,4,5-T emulsifiable esters forms a dual purpose
spray for the control of broadleaved vegetation containing both woody and herbaceous
species. Applications are usually in the region of 2 to 5 kg/ha a.e., but difficult or
persistent species may require special heavy applications.
Ammonium Sulphamate (AMS t or Ammate)
This is a highly soluble, crystalline chemical which kills many woody species.
Its main use is for application to out stumps or the stems of 2,4,5-T resistant species.
A solution of 400 g of AMS per litre of water is normally used, but the application of
small amounts of the chemical in crystalline form direct to the freshly out stump or
frill-girdle is also effective. It can also be applied as a foliar spray. Areas sprayed
or misted with AMS should not be planted until 12 weeks have elapsed after treatment.
This chemical rapidly corrodes all metal and should therefore be stored only in
plastic containers; spraying equipment should be thoroughly cleaned immediately after use.
Sodium Arsenite
This highly toocic chemical has found wide use throughout the tropics for frill-
girdling unwanted stems which are too large to be economically out and removed. Frill-
girlding with sodium arsenite is standard practice, particularly in the method of line-
planting in tropical rain forest areas. In the Solomon Islands, for example, this method
is normally used to poison over-wood stems, using an average of 170 g of sodium arsenite
per ha. Its great mammalian toxioity, however, constitutes a serious risk for personnel
handling it, and in many countries its use as a herbicide is prohibited. It is dangerous
to cattle or game, due to its attraction as a salt lick.
Pentaohlorophenol (PGP)
This chemical has been used in Papua New Guinea, (obtainable as a 15$ concentrate)
for foliage sprays killing annual broadleaved and grass weeds both in nurseries and in the
field.
Pioloram (4-animo-35t6-triohloropioalinio acid)
Pioloram, or tordon, is a post emergence, translocated herbicide extremely
effective against woody plants and particularly useful in preventing coppice growth.
Most grasses are tolerant. It has been used in southwestern Australia for killing
euoalypt growth in plantations of Pinus radiata, which is less susceptible to pi o lor am
than to 2,4f5-T* It is also used in controlling brush along right s-of-way, roadsides
and firebreaks and can be obtained as a water-soluble material for aerial application or
in pellets for hand or machine application.
-36-
Triazines
The triazines, including simazine and atrazine, act on emerging seedlings by
interfering with processes associated with photosynthesis. As they lack phloem mobility f
they are applied to the soil where they are readily absorbed by roots and translocated to
the foliage via the xylem. They are generally most effective with good soil preparation.
Atrazine is probably the triazine of widest agricultural use. In forestry it is
used as a preemergenoe herbicide in nurseries and plantations.
Simazine is also a preemergenoe herbicide but is more persistent in soils than
atrazine. Usually marketed as a wet table powder containing 50$ or 80% simazine f it is
generally applied to the soil before planting. In the United States simazine has been
successful in controlling grass and herbaceous weeds when sprayed along the planting lines
in early spring prior to planting with Scots pine. It is f however y most widely used in
forest nurseries for weed control in transplant beds.
Sodium Chlorate
This is a "total" herbicide applied to the soil for killing perennial vegetation
on roads, tracks and firebreaks and in depots and store yards etc. The soil remains
effectively poisoned for many months, and in the case of some species for a year or more*
Herbicides Specifically for the Control of Grasses
Competition by perennial grasses in young plantations is a widespread problem,
often retarding crop growth and giving rise to high weeding costs. Two chemical sprays
have so far proved satisfactory: dalapon and paraquat.
Dalaon
Dalapon is a translocated herbicide affecting only monocotyledons. Some grass
species are more susceptible than others* Agrostia, Desohampsia t Molinia and Nardus
species are very sensitive, Agrojgyron and Holous species less so. For pre-planting
control of grassy sites, a solution of 8 to 17 kg dalapon in 350 - 450 litres of water
per ha is sprayed not more than six weeks and not less than three weeks before planting.
This enables the crop to be planted into newly killed grass,
In planted areas dalapon can be effective in controlling grass between the rows
of young conifers at an application rate of 11 kg dalapon per ha without damage to the
conifers, provided that npraying is restricted to periods when the trees are dormant.
Control spraying should be repeated at intervals depending on the vigour of the regrowth.
Dalapon is one of the few chemicals which can be used to control monoootyledonous
water plants in ditches, water courses and ponds without endangering fish or other forms
of life in the water. Its effectiveness against weeds, sedges and rushes in wet sites is
often improved by mixing with 2,2,3-trichloroproprionic acid.
Paraquat (Qr am ox one)
This is one of the dipyridylium group of chemicals and acts by translooation. It
is quiokly absorbed and is extremely rapid in action against nearly all green growth.
Paraquat is particularly effective in killing annual grasses and fibrous-rooted or
stoloniferous species. It can defoliate woody species, but rarely kills them, so its use
is mainly confined to sites where grass or herbaceous weeds are troublesome. The chemical
is generally inactivated on contact with the soil so planting can follow shortly after
spray treatment.
-37-
Paraquat oan be used in young plantations, provided that the plants are well
screened from the spray. It is most effective in early spring before weed growth has
grown taller than about 20 - 25 om.
The rate of application is normally at 11 litres of gramoxone in 550 litres of
water per hectare treated. The chemical is highly poisonous and requires care in handling.
Methods of Herbicide Application
The main methods of applying herbicides are by apparatus carried by an operator,
by machine powered equipment or by aerial application. The most common equipment consists
of a range of knapsack sprayers, whioh are carried on the operator's back and, employing
compression, emit a fine spray through a jet. The direction, timing and type of spray
droplets oan be controlled by the operator. Other related types of applicators include
motorized knapsack mist blowers for low volume application of liquids and a similar item
designed for applying granular herbicides.
Ultra low volume (U.L.V. ) sprays are a more recent development which spread the
herbicide by producing large numbers of relatively uniform-sized droplets whioh are
dispersed evenly over the area by a fan, or by gravity and the natural movement of the air.
The basic applicator consists of a plastic tube which acts as battery holder and a handle
for the applicator head. The head contains a two-tier electric powered disc onto whioh
the herbicide is fed from a one litre reservoir. The disc has a serrated edge and when
rotated at high speed (up to 6 000 revolutions per second) produces an extremely fine
dispersal. The main advantage of the U.L.V. applicator is that the same dispersal of
active ingredient can be achieved with 2 to 10 litres of concentrate as would be attained
with 100 to 700 litres of diluted herbicide using conventional sprayers. In using the
U.L.V. technique, the saving in transport of dilutent is obvious, which offers new
opportunities in arid areas where water availability is a constraint to using conventional
spraying. The use of U.L.V. techniques is being developed in forestry, and a range of
investigations is being carried out in a number of countries.
There are a number of tools whioh are used to inject herbicides into the tissues
of undesirable trees or shrubs. Such equipment usually comprises an axe or chisel head
through whioh herbicide is injected from a reservoir when the cutting edge is applied to
the cambium. These tools offer a more sophisticated approach to frill girdling whioh can
be supplemented by spray or paint brush application of herbicide if required.
A range of equipment for larger scale operation has been designed for tractor
mounted or towed operation. The types of equipment are live reel sprayers, mist blowers
and granule applicators. Work on tractor mounted U.L.V. apparatus is under research and
development. Aerial application generally from fixed-wing aircraft, is perhaps the best
method of covering large areas quickly. The big risk in aerial application, however, is
drift of herbicide onto adjacent lands, water courses or crops, and this factor severely
limits its use.
Many of the herbicides have harmful or irritant effects on operators if protective
or safety measures are not taken. It is essential, therefore, that the possible effects
of any chemical should be fully studied before use, and that any recommended or legal
safety measures be applied. Using any of the herbicides requires the wearing of
protective clothing, often including gloves and face shields. Such requirements have
limited the use of herbicides in warm or hot climates.
-38-
Features of Herbicide Vegetation Control
One of the major advantages of successful chemical site preparation is that the
effect oan be longer lasting than that of other methods, and when so effective the problem
of unwanted regrowth is diminished. In areas liable to erosion, the killed vegetation very
often acts as a mulch, reducing the rate of erosion while presenting no competition to the
plantation orop, but in drier areas such dead matter contributes to the fire hazard.
Chemical clearing oan be used in terrain too difficult for mechanized methods. Although
chemical clearing may often be more costly than other methods, frill-girdling and basal
spraying techniques of killing unwanted stems have been developed for economic use in a
number of countries. A major disadvantage is that the need to oarry or have large
quantities of dilutents available on sites has restricted the use and range of ordinary
sprayers. Fortunately the development of ultra low volume applioatiors is likely to
diminish this problem.
BIBLIOGRAPHY AND REFERENCES
Adams, J.L. Prescribed burning techniques for site preparation in out-over jack pine in
1966 southeastern Manitoba. Pulp and Paper Magazine of Canada, December, 1966, 8 p.
Akwada, E.C.C. Report on tour to Ivory Coast to witness land clearing in rain forest
1973 conditions. 4 p. (Unpublished document).
Aldhous, J.R. Chemical control of weeds in the forest. Second edition. London, Her
1969 Majesty 1 * Stationery Office. 49 P* Forestry Commission Leaflet No. 51.
Allan, T.O. Notes on a visit to Ivory Coast with particular reference to land-clearing. 4 p.
1973a (Unpublished document).
Allan, T.O. Trial use of bullocks for cultivation in establishment of small-scale plantations
1973& or woodlots in Nigerian savanna areas. Samaru, Nigeria, Savanna Forestry
Research Station. Research Paper No. 13.
Allan, T.O. Handbook of plantation establishment techniques in the Nigerian savanna.
1977 Savanna Forestry Research Station, Nigeria. Rome, FAO. DP:NIR/73/007. Project
Working Document, p. 64.
Allan, T.Q., and Akwada, E.C.C. Land clearing and site preparation in the Nigerian savanna.
1977 In Savanna afforestation in Africa. Rome, FAO. FORiTF-RAF 95 (ISSN), pp. 123-138.
Allison, C.E. Provisional standard times for operations in industrial plantations. Zambia,
1970 FAO. (mimeographed).
Ball, J.B. Notes on chemical weed control in savanna plantation forestry. In Savanna
1977 afforestation in Africa, pp. 149-151. Rome, FAO. FORiTF-RAF "
Balmer, W.E. et al. Site preparation - why and how. Atlanta, Georgia, U.S.A., U.S.D.A.,
1976 Forest Service. Forest Management Bulletin, p. 8.
Bennouna, A. La mechanisation dans I 1 implantation du ride an forestier de I 1 oriental marooain.
1967 In Proceedings of FAO World Symposium on Man-Made Forests and their Industrial
Importance, Vol.2, pp. 1099-1120. Rome, FAO. FO/MMFj67-9a/3.
-39-
Blatchford, O.N. (ed.) Chemical control. The Entopath News, October, 1976* British Forestry
1976 Commission. 88 p.
Bol f M. The role of mechanization in small-scale forestry. In Proceedings of Joint IUFRO/
1976 FAO Meeting on Ways and Means of Reconciling silvicultural and operational
methods in modern forestry, pp. 48*64. Oslo, FAO.
British Forestry Commission. The safety of the herbicides 2,4-D and 2,4,5-T. Forestry
1977 Commission Bulletin No. 57, in press.
Brown, A.G. Soil preparation for plantation establishment in Australia. Paper for 15th
1971 IUFRO Congress, Gainesville, U.S.A. 11 p. (mimeographed).
Brown, R.M, Chemical control of weeds in the forest. London, Her Majesty's Stationery
1975 Office. 65 p. Forestry Commission Booklet 40.
Brown, R.M. f and Thomson, J.H. Trials of ULV applications of herbicides in British forestry.
1975 Commonwealth Forestry Review, 540)* 38-44.
Brunck, F. L'utilisation de phytooides dans les plpiniires et plantations forest! ires
1972 tropicales. Revue bois et ForJts das Tropiques, no. 141 1 31-39-
Burns, R.M. f and Hebb, E.A. Site preparation and reforestation of droughty, acid sands.
1972 Washington, B.C., U.S. Government Printing Office. U.S.D.A. Agricultural
Handbook No. 426, p. 61.
Caterpillar Tractor Co., The clearing of land for development. 111 p.
1974
Caterpillar Tractor Co., Land improvement contractors, application handbook. U.S.A.,
no date Caterpillar Tractor Co., AEO-30049-01 , p. 36.
Catinot, R. Formes speoiales de boisement-plantations en ligne, plantations d f enrichissement ,
1967 rideaux coupe-vent et brise-vent. In Proceedings of FAD World Symposium on
Man-Made Forests and their Industrial Importance, Vol. I, pp. 529-550. Rome,
FAO. FO/MMFi 67-1 1o/1.
Catinot, R. Results of enrichment planting in the tropics, jn Report of the Second Session
1970 of the FAO Committee on Forest Development in the Tropics, pp. 38-43* Rome,
FAO.
Centre technique forestier. Dlbroussaillement et destruction de la vge*tation indJsirable
1968 en forSt. In vent ai res des mat Uriels et des techniques. Paris. Cahier No. 78,
Slide II, Exploitations forestiires et soieries.
Chavasse, C.G.R. (comp.) Proceedings of the Symposium on Mechanization of Nursery Production,
1973 Forest Establishment and Tending in New Zealand. Rotorua, New Zealand, Forest
Research Institute. Vol. 1t proceedings and papers, 239 P* Vol. 2: appendices,
119 p. Forest Research Institute Symposium No. 13.
Chavasse, C.G.R. A review of land clearing for site preparation for intensive plantation
1974 forestry. In Proceedings of the IUHRQ Symposium on Stand Establishment, pp.
109-132. Wageningtn, The Netherlands.
Chavasse, C.G.R., and Fit spat rick, J* Weed control in forest establishment in New Zealand.
1973 Proceedings of the Fourth Asian-Pacific Weed Science Society Conference,
Rotorua, New Zealand, p. 267-273*
Cheney, N.P. Guidelines for fire management on forested watersheds, based on Australian
1977 experience. In FAO Conservation Guide No. 4. Rome, FAO. in press.
-40-
Council for Agricultural Science and Technology, Department of Agronomy, Iowa State
1975 University. The phenoxy herbicides. Weed Science, 23(3J* 25 3-263.
Crafts, A.S. Modern weed control. Berkeley, U.S.A., University of California Press.
1975 440 p.
Crowther, R.E. Guidelines to forest weed control. London, Her Majesty's Stationery
1976 Office. 7 p. Forestry Commission Leaflet No. 66.
Culpin, C. Farm mechanization. London, Crosby Lockwood and Son, Ltd.
1975
Deval, J.L. Mise au point sur 1'utilisation da mouvelles armes ohimiques en sylviculture
1970 tropioale. Revue Bois et ForSts des Tropiques, no. 132: 23-29.
Devjria, N.E. Final (technical) report: plantation mechanization. Industrial Forestry
1977 Plantations, Turkey. Rome, FAO. FO:DP/TUR/71/521. Working Document 27 f
p. 115.
FAO Report of the Second Session of the FAO Committee on Forest Development in the
1970 Tropics. Rome, FAO. 162 p.
FAO Some aspects of earth-moving machines as used in agriculture. FAO, Rome. 56 p.
1975 Agricultural Services Bulletin 27.
FAO Mechanization of irrigated crop production. Proceedings of an expert consultation
1977 held in Adana, Turkey, 5-9 April 1976. 404 P. FAO Agricultural Services
Bulletin 28.
FAO/ECE Culture meoanique du sol forestier. Geneva, Economic Commission for Europe.
1963 49+ P. FAO/ECE/LOQ/112.
Fleco Corporation. Land clearing equipment, (catalog of equipment).
1968
Foot, D.L. Nursery and establishment technique on the Vipya Plateau, Malawi, with special
1967 reference to the formation of a man-made pulp wood forest. In Proceedings
of the FAO World Symposium on Man-Made Forests and their Industrial
Importance, Vol. 3 f pp. 1545-1554. Rome, FAO. FO/MMFi67-5b/c.
Fryer, J.D. f and Evans, S.A. Weed control handbook. Vol. I: Principles. Oxford, Black well.
1970
Fryer, J.D. , and Makepeace, R.J. Weed control handbook. Vol. Ill Recommendations. Oxford,
1972 Blackwell.
Qratkowski, H. Silvioultural use of herbicides in Pacific Northwest forests. Portland,
1975 U.S.A., Pacific Northwest Forest and Range Experiment Station. 44 p. USDA
Forest Service General Technical Report PNW-37.
Oroulez, J. Conversion planting in tropical moist forests. Paper for Fourth Session of
1976 Committee on Forest Development in the Tropics. Rome, FAO. 22 p.
Qroupement Technique Forestier. Reboisementt Application des traitments par produits
1974 ohimiques phytocides pour le reboisement. Nogent-sur-Vernisson, France,
centre technique du finie rural, des eaux et des forSts, Minister* de
I 1 Agriculture. 39 p. Note technique No. 26.
-41-
aroupement Technique Forestier. Reboisements matlriels rofoaniques, 2nd ed. Nogent-sui>-
1975 VerniB8on f France, Centre technique du gfoie rural, dee eauz et dea forfrts,
Ministire de I 1 Agriculture. 51 p. Note technique no. 29.
Haines f L.W. et al. The effect of mechanical site preparation treatments on soil
1975 productivity and tree (Pinus taeda L. and P. elliottii Bigelm. var. elliottii)
growth. In Bernier, B, and Winget f C.H. (eds.), Forest soils and forest land
management, 379-395* Quebec, Lea Presses de 1'Universitf Laval.
Harrington, 0. f and Carter, N. Clearing bush in Uganda with tordon 101 mixture herbicide.
1972 Down to Earth, 28(3): 10-11.
Helgeson, E.A. Methods of weed control. Rome, PAO. 189 p. PAO Agricultural Studies No. 36.
1957
Institut pour le Developpement forestier. L'emploi des phytocides en sylviculture. Paris.
1971 8 p. Bulletin de la vulgarisation foreatiere no. 71/1.
Jackson, J.K. Enrichment planting. Secretariat note for Third Seas ion of Committee on
1974 Forest Development in the Tropics. Rome, FAD. 66 p.
Kenya Forest Department. Taungya in Kenyas the "shamba system 11 . In Proceedings of the
1967 FAD World Symposium on Man-Made Forests and their Industrial Importance,
Vol. 2, pp. 1057-1068. Rome, FAD. FO/MMFi 67-6/4-
Kimmins, J.P. Review of the ecological effects of herbicide uaage in forestry. Victoria,
1975 British Columbia, Canadian Forestry Service. 44 p. Information Report No.
BC-X-139*
King, K.F.S. Agri silviculture (the taungya system). Ibadan, Nigeria, Depart, of Forestry,
1968 University of Ibadan. 109 p. Bulletin No. 1.
Lamb, A.F.A. Artificial regeneration within the humid lowland tropical forest. In Report
1968 of the First Seasion of the FAO Committee on Forest Development in the Tropioa,
pp. 73-88. Rome, FAO.
Lamb, A.F.A. Enrichment planting in English-speaking countries of the tropics. In Report
1970 of the Second Session of the FAO Committee on Forest Development in the Tropics,
pp. 44-56. Rome, FAO.
Little, E.C-S. , and Ivens, G.W. The control of brush by herbicides in tropical and sub-
1965 tropical grassland. Herbage Abstracts, Vol. 35(l)i 1-11.
Moir, T. Burning off for planting. New Zealand Journal of Agriculture, November, 1970,
1970 5 P.
Mass on t J.L. SubsolaciSn. Unpublished report, Centro de Invertigaoiones y Capaoitacifin
1973 Fore stales, Cuba. 14 p.
Nash, C.A.M. Mechanisation in other parts of the world with particular reference to Africa.
1968 Paper for Group Study Tour on Mechanisation of Forest Site Preparation,
U.S.S.R. Rome, FAO (mimeographed).
Navarro Gaxnioa, M. , and Molina Rodriguez, J.J. Monicas de forestaoifin. Madrid,
1975 Institute Naoional para la Conservaoi6n de la Natural eia f Ministerio de
Agrioultura. 201 p. Monografia 9*
-42-
Norris, L.A. Behavior of pesticides in plant*, Portland, U.S.A., Pacific Northwest Format
1974 and Rang* Experiment Station. 6 p. U3DA Forest Service General Technical
Report PNW-19.
Olawoye, 0.0, The agri-si Ivioultural system in Nigeria. Commonwealth Forestry Review,
1975 Vol. 54 (3 and 4)1 No*. 161 and l62t 229-236.
Packer, P.E. Site preparation in relation to environmental quality* In Proceedings of
1971 Annual Meeting of Western Reforestation Coordinating Committee, pp. 23-28.
Portland, U.S.A., Western Forestry and Conservation Association.
Palmer, J.R. Forestry in Brazil - Arrazonia. Commonwealth Forestry Review, Vol. 56(2)1
1977 115-130.
Post, B.W. Soil preparation in stand establishment. In Proceedings of IUFRO Symposium on
1974 Stand Establishment, pp. 141-176. Wageningen, The Netherlands.
Roohe, L. The practice of agri silviculture in the tropics with special reference to
Nigeria. In Shifting cultivation and soil conservation in Africa, pp.
179-190. Rome, FAO. Soils Bulletin 24.
Rogers, E.V. Ultra low volume herbicide spraying. Edinburgh, Scotland, Her Majesty's
1975 Stationery Office. Forestry Commission Leaflet 62, p. 20.
R8hrig, E. Herbicides for site preparation with stand establishment. In Proceedings of
1974 IUFRO Symposium on Stand Establishment, pp. 133-140. Wageningen, The
Netherlands.
Romanoier, R.M. 2,4-D, 2,4,5-T and related chemicals for woody plant control in the
1963 southeastern United States. Mao on t Georgia, U.S.A., Georgia Forest Research
Council. Report Number 16, p. 46.
Sampson, A.W., and Sohultz, A.M. Control of brush and undesirable trees. Rome, FAO. 49 P
1957
Shipman, R.D. Preparing planting sites with herbicides. Tree Planters 1 Notes, 26(1)1 1-4.
1974
Tarrant, R.F. et al. The future role of chemicals in forestry. Portland, U.S.A., Pacific
1973 Northwest Forest and Range Experiment Station. 10 p. USDA Forest Service
General Technical Report PNW-6.
Terenoio da Silva, F. , and Lourenco, M. The importance of the utilization of bulldozers in
1977 the development of oerrado soils in Brazil t Jn Mechanization of irrigated
crop production, pp. 165-177. Rome, FAO. Agricultural Services Bulletin 28.
Walstad, J.D. Weed control for better southern pine management. Hot Springs, U.S.A.
1976 Weyerhaeuser Company. 44 p. Weyerhaeuser Forestry Paper No. 15.
White, K.J. Notes on enrichment planting in lowland rain forests of Papua New Guinea.
1976 Boroko, Papua New Guinea, Office of Forests. 13 p. Tropical Forestry Research
Note SR.31.
Williston, H.L. et al . Chemical control of vegetation in southern forests. Atlanta, U.S.A.,
1976 Southeastern Area State and Private Forestry, USDA Forest Service. 6 p.
Forest Management Bulletin.
Wittering, W.O. Weeding in the forestt a woxfc study approach. London, Her Majesty's
1974 Stationery Office. 168 p. Forestry Commission Bulletin No. 48.
-43-
CHAPTER 2
DIRECT SOWING
GENERAL CONSIDERATIONS
Onoe the area to be afforested has been prepared, the forest crop is introduced
either by sowing the tree seeds directly or by planting forest nursery stock, stumps,
wildlings or cuttings. The choice of whether to sow or to plant depends on a number of
factors* The factors favouring the choice of direct sowing arei
1) Cost. Direct sowing, when successful, is usually cheaper than planting:
it avoids the cost of raising nursery plants and generally is a less
costly operation than planting* Costs can be further reduced if aerial
seeding methods are possible, especially in areas of difficult access*
2) Abundance of cheap seed* Direct seeding requires much greater quantities
of seeds to secure a reasonably full stocking than is required by
planting nursery stock. A critical factor, therefore, is the possibility
of procuring large quantities of seed easily, and at low cost, as is
often the case when local species are used*
3) Seeds which do not grow well in nurseries* The seeds of certain species
(e.g. Pinue roxburghii of the Himalayas) are difficult to raise in
nurseries, and direct sowing gives better results* Plants of most
species suffer from the shook of being transferred from the nursery to
the planting site, and in acme oases direct sowing might give better
results* Plants resulting from direct sowing, for example, particularly
in fine textured soils, often have better root development than nursery-
grown seedlings field planted in notches where root development is often
restricted to the plane of the planting slit*
4) 3eads of easily established fast-growing species, or of species growing
on sites where competing vegetation is negligible. Direct sowing is
preferred where seedlings grow fast enough to survive and outstrip
competing vegetation on the site, making a prolonged period of tending
and weeding unnecessary; otherwise the financial advantage of sowing
is loot. Direct sowing from the air has been employed very successfully
-44-
for seeding Pinue radiata on short grass sites in parts of New Zealand
and for various other pines in the southern U.S.A. as well as in the
prairie provinces of Canada* In Finland direct seeding of Soots pine
on some types of recently drained peat bogs without other soil
preparation is a common practice (the wet surface offers a good
germination substrate 9 the competing vegetation is less abundant and
pests and diseases are more scarce than on mineral soils)*
5) Adequate germination. The species selected must give reliable and
fore oast able germination under field conditions. Often species with
large seeds are preferred because they give large seedlings which
resist adverse environmental conditions better than smaller ones*
The main disadvantages of direct sowing are:
1) The relatively large quantities of seed needed to offset losses from
seed-eating birds, rodents and insects, as well as losses due to
climate | soil and competing weed growth. Other sources of seedling
loss are frost, which freezes seedlings or lifts them out of the
ground (i.e. frost heaving) , and animals that browse or trample
seedlings. If the cost of obtaining seed is high, for example, when
using imported seed, or seed of special provenances or from seed
orchards, or when it is difficult to obtain adequate supplies, it is
often more economical and efficient to raise nursery stock.
2) The irregular stocking, especially with broadcast sowing and, therefore,
the less efficient use of the growing space, compared with planting
methods. Too dense stocking will require an early cleaning or reduction
operation. This was the case in New Zealand where such additional work
reduced much of the cost benefit of direct sowing. On the other hand,
continuous changes in the site (e.g. soil fertility) are utilized more
efficiently when using direct sowing.
The economies possible by sowing from the air have encouraged research into methods
of embedding the seed in pellets containing anti-pest chemicals and materials designed to
aid germination. Successful developments in these fields have made direct sowing a
commonly used and practical afforestation method in many parts of the world. Nonetheless,
the trend is towards planting which, though more costly, is generally more certain and
allows greater control over the crop.
PRE-SOWINQ TREATMENT OF THE SEED
Some seeds are ready for sowing as soon aa they are collected from the parent tree;
others pass through a dormant stage during which the embryo completes its development.
Often a pre-treatment is used to hasten germination, or to obtain a more even germination*
The types of treatment vary with the different types of dormancy of tree seeds; the matin
types of dormancy are:
1) Exogenous dormancy, connected with the properties of the
pericarp or the seed coat (i.e. mechanical, physical or
chemical) ;
2) Endogenous dormancy, determined by the properties of the
embryo or the endosperm (i.e. morphological or physiological)
and
-45-
3) Combined dormancy.
Pre-Treatment Methods for Overcoming Exogenous Dormancy
Soaking in Cold Water
With a great number of species, soaking in oold water from one to several days is
sufficient to secure germination* The improvement in germination caused by soaking in hot
or oold water is caused by the softening of the seed ooat and the ensuring of adequate
water absorption by the living tissues* Cold soaking is used Y for example, for the
Himalayan pines and in Japan for pine and spruce seeds* When long soaking periods are
used it is recommended that the water be changed at intervals* It is usually important to
sow the seed immediately after soaking without drying, because drying generally seriously
reduces the viability of the seed* An exception to this is Acacia mearnsii in southern
Africa which is dried after hot water treatment and stored for three weeks* Also, in some
countries teak seed is given alternate soaking and drying.
Soaking in Hot or Boiling Water
The seeds of many leguminous species have extremely tough outer coats which can
delay germination for months or years after sowing unless subjected to pre-treatment by
immersion in boiling water* Examples are Acacia deourrens, A* mearnsii and A* arabioa*
The seed is immersed in two to three times its volume of boiling water where it is allowed
to soak until the water is cold* The gummy mucilaginous exudations from the seed ooat are
then washed off by stirring in several lots of clean water.
Sometimes acorns, chestnuts and similar fleshy seeds give better germination if
scalded, that is dipped for only 15 - 30 seconds in boiling water, which kills the insects
and grubs often found on the seeds* If the scalding is prolonged above one minute,
however, the seed may be killed*
Acid Treatment
Soaking in solutions of acid is used in the case of seeds with very hard seed
coats such as Acacia nilotioa and Albizzia lebbeok* Concentrated sulphuric acid is the
chemical most generally used; after soaking the seed must be immediately washed in clean
water. Tests should be made to determine the optimum period for treatment for each species,
and even for different provenances, since over-exposure can easily damage the seed*
Examples of the recommended times for soaking in acid of seeds of a few Acacia
species are ( Laurie, 1 974) *
Species Time (minutes)
A, albida 20
A. nilotioa 60 to 80
A. Senegal 40
Other Treatments
In special oases seeds are scarified, for example in revolving drums, to crack or
pierce the outer seed coat* Sometimes the seed has to be cracked or out open, or
partially out by hand (e.g* Pterooarpus angolensis and P. pedatus) to obtain good
germination* Germination of Pinus lambertiana was improved by removing the seed ooat and
membrane* In some countries (e.g. India and Sudan), seeds of Acacia and Prosopis species
-46-
are fed to goats and later collected from their droppings; the partial digestion in the
gut is held to enhance germination, but the method has obvious difficulties in application
and is now only used if aoid treatment is not possible*
Pre-Treatment Methods for Overcoming Endogenous Dormancy
Stratification
Stratification means the storing of seeds in a moistened medium, for example peat
or sand, so as to maintain viability and overcome dormancy* If seed is stored moist in
near-freezing temperatures, the method is called cold stratification or pre-ohilling f
even if no medium is used* Stratification is commonly used for large, fleshy seeds, such
as acorns, walnuts and teak* The seed is usually stored in a pit or trench in alternative
layers with moist sand, peat, leaves or straw, and the heap is covered to keep rain off
and protect from the depredations of rodents*
Moist oold stratification is commonly used to break dormancy or improve germination
for a range of pine seeds ( Schubert and Adams, 1971 ) In this methods
1) The seeds are thoroughly mixed with moistened sterile river sand or
verraioulite;
2) The mixture is poured into trays or cans with bottom drainage holes
and
3) The containers are placed in refrigerators at 0.5 to 2.0C for the
period to break dormancy.
The medium has to be kept moist through the stratification period* To minimize
the formation of moulds the seed should be treated with a fungicide such as Captan before
stratification. An alternative method is to soak the seed for one or two days and, after
draining off the excess moisture, to seal the seed in polythene bags for storage at to
200. The time required to break dormancy is variable, for example Peeudotsuga menziesii
takes 40 to 150 days depending on the origin of the seed and Pinus ponderosa required
some 30 days, so that trials and investigations are necessary to determine optimum periods
for species in selected areas*
In Japan a form of stratification under snow is practised to quicken the
germination of certain species (e.g. Abies saohalinensis. A. homolepis, A, firma). After
a short wetting the seed is spread evenly on a prepared siTe and oovered""in clean river
sand. The sand is then covered with straw upon which a pile of snow 1.5 to 2 m thick is
packed. The snow is replenished from time to time until the spring thaw arrives and the
seeds are ready for sowing*
Warm followed by oold stratification has been found effective for a considerable
number of species (e.g* Fraxinus excelsior). The seeds are held at germination
temperatures for one to several months, after which they are shifted to oold chambers or
refrigerators and held at low temperatures for an additional one to several months.
Treatment with Chemicals
Chemicals, such as hydrogen peroxide, have been found effective in breaking
internal dormanoy in most seeds (e.g. Pseudotsuga. Abies and southern U.S.A. pines).
Oibberellio aoid has been shown to enhance the germination capacity and even to
stimulate meristematio growth rates, while a number of forest tree seeds respond to
treatment with various organic compounds, including citric and tartario aoid. Other
tested and effective chemical treatments have included potassium nitrate (l - 4# for
24 hours) and red copper oxide or lino oxide dusts.
-47-
Pre-Treatment Methods for Ove rooming Double Dormancy
To overcome double dormancy it is necessary to treat the seed so ate to make the
seed ooat permeable and induce in the embryo the changes essential for germination.
Sometimes oold stratification is suffioient f but more often hot water soaking, acid
treatment or scarification followed by stratification is necessary. Warm followed by
oold stratification has also given good results in many oases*
SEED COATING AND PELLETING
Where seed-eating pests cause serious losses, the seed should be treated with
insecticides and rodent and bird repellents before sowing* Chemicals such as ar sen ate
and endrin are used against insects and rodents; arasan and anthraquinone are effective
bird repellents and fungicides*
The development of seeding from the air has stimulated experiments in coating the
seed with hygrosoropio substances containing nutrients and toxic repellents* These
artificial coatings add weight to some of the lighter seeds y thereby improving the scatter
pattern in aerial seeding* A coating formulation consisting of endrin and arasan as the
repellents, with a latex sticker to act as a bond, has been successfully used with Pinus
palustris and P. taeda in southern U.S.A. The seedling yields in field studies comparing
coated seed with untreated seed were 55 : 1 for P* palustris and 12 t 1 for P. taeda
(Derr and Mann, 1971 ). Aluminium powder has been found useful as a lubricant for seed
pellets. In East Africa Rhizootol oombi is used in pelleting P. patula seed as a
protection against damping off.
SITE PREPARATION
In most oases, direct sowing will not be successful unless the seed is in contact
with mineral soil and preferably covered by a thin layer of protecting earth. Exposure
of the mineral soil can be achieved by burning or by clearing and cultivating. Controlled
burning is an important method of site preparation for euoalypts in Australia, especially
in the wetter forest types and is also used extensively for aerial sowing of pines in
southern U.S.A.
Land clearing and cultivation prior to sowing may be done on the whole area to be
seeded or it may be restricted to strips or spots. On sloping land cultivating is
generally done in bands (either continuous or interrupted) following the contour. Where
soil erosion is a danger, it is usual to leave the native vegetation undisturbed in the
bands between the cultivated strips.
In Tanzania a method called n tie-ridging 11 has been found effective, especially
for Cassia siamea plantations* With this method the whole area is cultivated and ridges
are built up at intervals by hoeing. Tie-ridging is generally used on gently sloping
land where the basins are very effective in controlling surface runoff. Sowing the seed
along the ridges has given very good results. Wherever possible the growing of a forest
crop is combined with the raising of food crops.
The Indian "rab" method is also used in some dryer regions of the savanna type.
The rab method consists of piling the slash cleared from the land in windrows or heaps
and burning it when dry. The seed is sown directly on the ash after burning. The
advantage of this method is that the burn partially sterilizes the soil, killing all
weed growth and the surface population of termites and ants. The rows remain free of
weeds fer an appreciable period, and the ash provides a useful fertilizer for the
seedlings. In Zambia a similar method, called "oitemene" was used, but has been
abandoned because of problems in carrying out a timely burn over large areas and in
protecting the young crop from fire.
-48-
TIME3 FOR 30WINQ
In general, sowing should be done when soil conditions are sufficiently moist and
warm to permit germination to start and to promote rapid early growth of the seedlings,
that is to say in the spring or at the onset of rains. Moisture and rainfall are the
main oritioal factors so actual sowing dates may vary from year to year. If sowing is
prescribed on a preselected date regardless of soil moisture, there is a risk that initial
rains will be sufficient to start germination but inadequate to sustain it. The soil
should also be free of frost, but with some species higher soil temperatures are necessary
for germination*
In areas subject to snowfall, especially in drier regions, there are sometimes
advantages in sowing before the snow season. The seed is protected by the snow from birds
and other seed-eating animals during the winter, and germinates immediately after snow-
melt when conditions are favourable, which is an advantage when the onset of dry summer
weather follows very soon after the thaw. In other oases, the seed is sown immediately
after the snow has disappeared or sometimes on the surface of the snow as soon as the thaw
conditions have set in.
In southern US*A (Derr and Mann, 1971 ) sowing may be done during the spring or
autumn, but best results are generally obtained from early spring sowing. In California,
however, late autumn seeding offers a longer seeding period, avoids the need to stratify
and results in earlier germination in the spring.
DIRECT SOWiyq METHODS
Broadcast Sowing
Broadcasting seed can be done by hand, by using a tractor mounted spinner of the
type used in agriculture for spreading complete fertilizer or aerially by using aeroplanes
or helicopters. Broadcast sowing is used for many species but requires muoh more seed per
unit area sown (two or more times the quantity used in the other methods mentioned). It
is used in circumstances where the seed supply is abundant and cheap and pre-supposes that
only a relatively small percentage (30$ or less) of the germinating seeds survive to
establishment. If germination and survival conditions are good, then broadcasting may
well result in too high a stocking of the land, requiring subsequent drastic reduction of
the crop by hand or mechanical weeding methods. In such conditions line sowing, drilling
or even spot sowing is less wasteful of seed. However, when seeding from the air is
feasible, then over-stocking with subsequent thinning out of the seedlings is sometimes
considered acceptable.
In New Zealand Pinus radlata plantations have been extensively established by
aerial broadcasting, and in Canada direct sowing of Pinus oontorta, Pinus banksiana and
Pioea glauoa. partly from the air and partly by using tractor mounted seeders, is widely
used, thanks to developments in seed-coating techniques. In Canada from 150 to 450 g/ha
of seed is used in broadcast seeding depending on the species and the locality of sowing.
Broadcast seeding from the air has also been highly successful on a large scale
for sowing Pinus elliottii and other fast growing pines in the southern states of U.S.A.
It is the quickest and cheapest method, an aeroplane seeding 600 hectares per day and a
helicopter up to 1 000 hectares. Broadcast seeding by machine is muoh slower, covering
up to 35 hectares a day, while 8 hectares is about the maximum a man oould seed a day.
The possibilities of reclaiming sand dune areas by aerial seeding followed by
spraying the land with a coagulating chemical to fix the blowing sand is referred to in
Chapter 4*
-49-
Wherever possible the seed should be covered for protection with a layer of soil
of a depth equal to two or three times the diameter of the seed. Where the land has been
previously clean cultivated this can be achieved by rolling the seeds in with a tractor
drawn agricultural roller or by dragging a rounded log or baulk over the land with ropes
or chains attached to each end and yoked to a tractor or to draft animals. Covering the
seed has a marked effect on increasing the survival germination percentage*
Sowing in Lines or Drills
Sowing in lines may be conveniently used either on clean cultivated sites or on
land cultivated in lines or strips. The seed is sown by hand or can be drilled in with
a modified agricultural seeding drill. Line seeding uses one-half to one-third the
quantities of seed required for broadcasting. It is also the method best suited to sowing
large seed. The distance apart of lines can be selected on the basis of growth rates or
subsequent tending methods, and the spacing of seed in the line should be such as to ensure
an adequate density of stocking.
Hand sowing in lines is still commonly used in many count ries t particularly for
small-scale afforestation schemes. It is the only possible method on planting sites
prepared with tied-ridges and along contour trenches and gradoni on steep slopes. Seme-
times a shallow furrow is drawn into which the seeds are dropped before closing the furrow
in with a hoe or rake.
Very large seeds oan be dibbled in holes made in the soil by a pointed stake* In
Brazil the seeds ef Arauoaria an gu at i folia are dibbled in holes 10 to 20 om deep at
spacings of 1 to 3 ra within the rows and 1 to 3 m between rows (Ntima, 1968). Prom one
to three seeds are sown in each hole* A similar method is used with this species in
Argentina, where lines are 1 m apart and within row spacing is 0.5 m. This close
spacing requires 40 to 120 kg of seed per hectare* At year three the seedlings are
thinned out to 2 500 plants/ha* Line seeding is also the general method used in Italy
for Pinus pinea plantations; 50 - 120 kg of seeds per hectare are used f and the seeds
are buried "a finger's depth 91 in the soil*
Where possible drilling with tractor drawn implements is eften mere timely and
efficient than sowing by hand* A tractor and drill oan seed 5 hectares a day while 25
men would be needed to do the same work in the same period* In Canada a specially
designed drill seeder has recently come into use which is towed by a crawler tractor
fitted with a V-shaped dozer blade* Use of this machine allows scarification of the
soil and seeding to be carried cut in one operation*
Spot-Sowing
In this method, seed is sown in relatively small cultivated patches spaced at
regular intervals corresponding to the desired crop spacing. Spot sowing is commonly
used for such genera as Swietenia or Qroelina in the tropics with 2 or 3 seeds being sown
in each spot*
In New South Wales, Australia, spot-sowing is the standard method of establishing
plantations of Eucalyptus pilularis and E* grandis. The land is first cleared of
vegetation which is later burned in situT The seed is sown on the ground in small spots of
20 om diameter at intervals of 2.35 x 2.80 m or 3 m x 3 using a seed shaker or "pepper
pot" container consisting of a screw-topped jar, or a plastio container with perforated
lid through which the seed oan be shaken but will not flow freely* Sowing rates for
these species vary between 250 and 500 g per hectare. The same method is used for
sowing Eucalyptus seed in Zambia and the Congo; however in these areas it has not
succeeded as well as in New South Wales, where the two speoies are native. In general,
Eucalyptus spp. in exotic sites are more successful if planted*
-50-
^LK^$*
'v^x^t^' ^y* 1 * ' * ^^ ?^?^ * ^^ ^i^^y^t-^fc^ * *
* :& % ^.^>iA* " - J^f- ' t ^ ^WffJWJ;
t -W^r - '^/9> /? * CW 1 v * ttlwl^
The Panama direct seeder is a lightweight hand tool used for spot sowing directly
onto mineral soil* It has a trigger dispenser and an adjustable hole size which
allows the operator to control the number of seeds released per spot. (Courtesy
U.S. Forest Service)
The spot sowing method is commonly used for establishing conifer plantations in
hilly regions, particularly in some Mediterranean countries, in the Himalayas and in Japan.
In Japan the spots are about half a metre in diameter and are sown with about 30 seeds of
Pinus densiflora which are covered by lightly raking over the spot.
Spots may take the form of rectangles which are often about 1.5 m wide and 2 - 4 m
long, with the longer axis oriented along the contour. These rectangular spots are cleared
of shrubby growth and cultivated with a mattock or hoe. In Italy, Pinus pinaster and P.
larioic are normally sown in this way or on continuous cultivated strips using 6 - 15 kg
of seeds per hectare. The method is also used extensively in Cyprus for re-seeding burned-
over forests with P. brut i a. Similar methods have been used with success for establishing
Cedrus deodar a t Pinus griffithii and P. roxburghii using 2.1 kg of Cedrus seed and 1.5 kg
of pine seed per hectare. Almost double this quantity of seed is needed for sowing along
continuous contour lines.
Another varient is "mound" or bed sowing, especially on moist sites or in poorly
drained soils, where the soil is excavated from pits and deposited in a series of small,
flat-topped mounds, on which the seed is sown or dibbled.
-51-
Spot sowing is sometimes used in taungya plant at i mm , the spots tola* narked bj a
stake driven into the ground so that the cultivator can take precautions against injuring
the seedlings during weeding or harvesting uprk.
Replacement Seeding
Failures after seeding operations are filled by re-seeding the following year or
by transplanting seedlings found growing in excessive numbers in other parts of the area*
In the oase of fast-growing speoies f it is advisable to fill the blank spots by planting
nursery grown plants rather than to attempt re-seeding. An essential is to determine the
reason for any failure, in an attempt to ensure that any casual factors will not similarly
affect any re-seeding.
BIBLIOGRAPHY AND REFERENCE
Appelroth, S.E. Work study aspects of planting and direct seeding in forestry. In IUPRO
1974 Symposium on Stand Establishment! pp. 202-275* Wageningen, The Netherlands.
Cayford, J.H. (ed. ) Direct seeding symposium. Ottawa, Canada, Department of the
1974 Environment. 178 p. Canadian Forestry Service Publication Mo. 1339*
Derr, H.J., and Mann, W.F. , Jr. Direct -seeding pines in the South. Washington D.C.,
1971 USDA Forest Service. 68 p. Agriculture Handbook No. 391.
Hadri, H. , and Tschinkel, H. Semis direct de pin d'Alep. Ariana, Tunisia, In at i tut
1973 National de Reoherohes Forestieres. 26 p. Note de Recherche No. 5*
Kerr, E. Can direct seeding bridge the South 1 s "regeneration gap"? Journal of Forestry,
1975 November, 1975 * 720-723.
Laurie, M.V. Tree planting practices in African savannas. Rome, FAO. FAO Forestry
1974 Development Paper No. 19, p. 185*
Lohrey, R.E. Site preparation improves survival and growth of direct-seeded pines. New
1974 Orleans, U.S.A., Southern Forest Experiment Station. 4 p. USDA Forest Service
Research Note 50-185.
Mann, W.F. Jr. et al Status of aerial row seeding. Forest Farmer, 34(2)t 12-13, 38-40.
1974
Ntima, 0.0. The arauo arias. Oxford, Commonwealth Forestry Institute. 139 P ?** Growing
1968 Timber Trees of the Lowland Tropics No. 3
Rietveld, W.J. , and Heidmann, L.J. Direct seeding ponderosa pine on recent bums in
1976 Arizona. Fort Collins, U.S.A., Rooky Mountain Forest and Range Experiment
Station. 8 p. USDA Forest Service Research Note KM-312.
Schubert, O.K. , and Adams, R.S. Reforestation practices for conifers in California.
1971 Sacramento, U.S.A., Division of Forestry, State of California, p. 359-
USDA Forest Service. Pine seed drill. San Diraas, U.S.A., Equipment Development Center.
1967 24 p. Equipment Development and Test Report 2400-1.
Williston, H.L., and Balraer, W.B. Direct seeding of southern pines - a regeneration
1977 alternative. Atlanta, U.S.A., Southeastern Area State and Private Forestry,
USDA Forest Service. 6 p. Forest Management Bulletin.
-53-
CHAPTER 3
PLANTING AND TENDINQ
PLANTINQ
The decision to afforest on a reasonably large scale should always be based on a
series of trials or research to determine effective methods of establishment* Both direct
seeding, primarily because of its possible cheapness, and planting with nursery stock
should be considered, but planting is by far the most common method.
Planting allows for regular spacing which favours good utilization of the site and
facilitates subsequent tending operations and plantation management* On difficult sites,
particularly in dry regions, planting has proved by far the most effective method, indeed
often the only method, of establishing plantations. It is also often the most successful
method for fertile productive sites where competition from weed growth is fierce* When
seed supplies are scarce or costly, nursery production and planting offer the best
opportunity of using seed efficiently; while in circumstances where plants are reproduced
vegetatively, such as hybrid poplars or species that produce little or no viable seed,
there is no alternative to planting.
The main disadvantages of planting when compared with direct sowing are the cost
and time required to produce nursery stock, the high costs and transport problems in moving
stock to planting sites without deterioration in their condition and the increased
requirements in number and skill of planting teams. Unskilled or careless planting often
results in poor survival or in root deformation that adversely affects growth and stability.
The essential principles of planting are that:
1) The planting stock should be healthy and vigorous;
2) The selected trees should be suited to the planting site,
and such sites should be prepared to a condition favour-
able for the tree crop, and
3) Planting should be carried out in an efficient and timely
fashion and the seedlings should be given proper care and
protection during and after the planting operation.
-54-
Kinds of Planting Stock
The kind of planting stock used has a direct bearing on the planting method. The
main types of planting stock are bare-rooted, ball-rooted, potted and tubed plants, stumps,
cuttings and set**
Bare-Root Plants
Bare-root plants are despatched from the nursery after shaking the excess earth
from the roots, leaving only a thin layer for protection. The plants are tied in bundles
and protected from drying in transit by covering the roots with wet moss or leaves or by
dipping them in clay slurries or specially prepared mixtures. The bundles are placed in
paper or plastic sacks, cardboard cartons etc., for despatch. Plastic bags or paper sacks
lined with plastic film have the advantage of being permeable to oarbon dioxide but
impermeable to water, thus minimizing the risk of drying. Bare-root plants are most
frequently used in temperate regions or in other regions where the climate has a
relatively high atmospheric humidity during the planting season. In temperate regions,
seedlings are generally in a resting phase at the time of planting, and this facilitates
bare-root planting. However, plants are liable to a loss of viability, even in humid
climates, if the roots are exposed to sun or wind; they should, therefore, always be kept
covered on delivery at the planting site until the time for planting out arrives. When-
ever there is a possibility of a delay of more than a few hours between delivery and
planting, the bundles should be "heeled in" - that is to say, placed in specially dug
trenches and the roots covered in moist sand, peat or light earth. Plants that have been
carefully heeled in and kept watered can survive several days, even weeks, without damage.
"Striplings" are large nursery plants with a 1 to 2 m shoot which is stripped of
leaves prior to despatch for planting. Stripping off the leaves reduces transpiration
losses. Such plants are used mainly in the tropics where browsing is a special hazard.
"Wildings" are natural forest seedlings or root suckers which are sometimes used
for planting when nursery stock is either too small or in short supply. They are most
often used in enrichment planting operations.
Ball-Rooted, Potted or Tubed Plants
In ball planting, the plants are despatched from the nursery with their roots
enveloped in nursery soil, which protects them from drying and reduces physical damage
to the roots as a consequence of lifting from nursery or transplant beds. A method
developed in Bast Africa, for example, is to carve up the nursery bed into sections and
to place the sections into shallow-sided boxes, or to grow the seedlings directly in the
boxes. At the planting site, individual seedlings with small blocks of soil are out from
the box for planting.
The main problem with ball planting is to prevent the soil from being shaken loose
from the roots during transit from the nursery to the planting site. To overcome this,
different techniques have been tided, such as enclosing the bare roots of nursery stock
in balls or blocks of specially mixed and compressed earth (usually consisting of clay,
sandy loam and peat or humus in equal parts), or in earth-filled containers. Stock thus
treated are termed "balled-plants 19 * In a similar method developed in Brazil, and formerly
used on a large-scale, the potting soil is compressed by a machine to form a soil block,
called a torrao paulista, into which seed is sewn.
On a much wider scale, the problems of root exposure have been largely overcome
by the use of seedlings raised in some form of container* Plantation systems using
container-grown stock are now common in most parts of the world, and are used almost
exclusively in areas with a marked or long dry season. Container plants have a
considerable capacity to withstand limited dry periods following planting; their use
-55-
therefore oan prolong the planting season, particularly in temperate zones, and to a muoh
lesser degree in harsh environments*
Containers oan be either "pots", whioh have a closed bottom, preferably with
drainage holes, or "tubes", whioh have no bottom but require a soil medium that is
sufficiently adhesive not to fall out when handled.
The use of containers made of polythene has become widespread; but prior to their
development, various other materials such as metal, bamboo, wood veneer, banana or palm
leaves, cardboard and waterproof paper were widely used in different parts of the world.
Although still used in some areas, most of these are either more expensive or less
convenient than polythene, whioh has the advantages of being cheap, light and easy to
handle and has generally proved effective over a wide range of conditions. The polythene
used for containers is usually 150 to 250 gauge (0.0375 to 0.0625 mm thickness) and is
generally black or transparent, the black being more durable.
The size of container varies with species, age and size of stock preferred for
planting as well as harshness of the site. In Nigeria, for example, in areas with less
than 800 mm of rain, and a dry season of at least six months, pots 25 cm long by 25 cm
circumference are used, while in areas with over 800 mm rainfall, smaller pots 15 cm by
25 cm are used, and experiments using pots 15 cm x 15 cm are being actively continued. In
Zambia tubes 15 cm by 25 cm were standard, but "minipots" 15 cm by 15 cm have been
developed and are extensively used. The size of a container has an obvious effect on its
weight when filled with soil. For example, in Nigeria the different sizes of pot filled
with soil weigh approximately: large, 1.9 kg; medium, 1.1 kg and small, 0.4 kg. The work
input and cost of transporting container seedlings increases with the size of container,
whioh underlines the impetus for research into the use of minipots and "tubelings". An
objective in container planting should be to use the smallest container compatible with
successful establishment and subsequent growth and development.
The use of containers has occasionally caused root malformation of seedlings, with
an adverse effect on their subsequent growth and development, and one disadvantage of
small pots is that they may increase the chance of such malformation (Ball, 1976). When
plants are kept too long in containers, the restriction of lateral root growth may cause
distortion, coiling and spiralling whioh may later lead to basal stem snap, reduced wind-
firmness and stunted growth, and in extreme oases it may result in mutual strangulation of
roots and the death of the tree. These symptoms, however, may riot always appear, or may
not become apparent until some years after planting. In Nigeria, for example, in trials
of removal, partial removal or retention of polythene bags at the time of planting, there
were indications of increased mortality in four-year-old pines when bags were not removed,
but in euoalypts up to seven years old removal made little difference vPAD, 1976) To
reduce the risk of root coiling, it is important to time nursery operations so that plants
do not become too large for their containers before out-planting; and to mitigate the
damage from coiling it is advisable to completely remove the container at the time of
planting. In addition, Ben Salem (l97l) f Stone (1971) and Donald (1968) recommend making
two or three vertical incisions about 1 cm deep down the length of the soil cylinder with
a sharp instrument to out any coiling roots.
In recent years new types of container have been developed in North America whioh
are designed to minimize root coiling (Tinus ert al. , 1974) The inner walls of these
containers have vertical ribs whioh channel the roots to a central bottom hole. By
supporting the containers clear of the ground, emerging roots are killed back by "air
pruning 11 , thus encouraging growth of numerous laterals into a tapered form. The plant and
growing medium (together called a "plug") are removed from the container at the time of
planting and are inserted into the soil with the add of a specially made dibble*
-56-
Stumps. Cuttings and Sets
"Stump 11 is a term applied to large nursery stock of certain broadleaved species
which has been subjected to drastic pruning of both the roots and the shoot* The top is
generally out back to about 2 cm and the root to about 22 cm (Parry, 1956). Stump
planting is especially suitable for taproot dominated species and is frequently used when
establishing teak, gmelina and a number of other important tropical genera (e.g. Afzelia,
Cassia, Chlorophora, Bit androphragna, Khaya, Lovoa. Pterooarpus, Terminalia, Triploohiton
Bisohofia, Dalbergia and many Leguminosae. Stumped plants of Acacia oyanophylla are also
used in arid zone drift sand stabilization plantations. During transit stumps are
normally covered with wet sacks or layers of large leaves*
Cuttings and sets are also commonly used as planting stock in reforestation
programmes* A cutting is a short length out from a young living stem or branch for
propagating 9 i.e. producing a whole new plant when planted in the field* A rooted
cutting is one that has been rooted in the nursery prior to field planting* Sets are
long, relatively thin, stem cuttings or whole branches, such as those sometimes used for
propagating willows*
Trees easily and commonly propagated by cuttings include poplars, willows and
gmelina. For some harder to root species, rooted cuttings are sometimes used in reforest-
ation to supplement scarce seed supplies and as a means of tree improvement (Brix and van
den Driessohe, 1977)* Rooted cuttings of Crypt omeria japonioa, for example, are common
in Japan, and Pioea abies rooted cuttings are used in West Germany and Finland* Extensive
research on rooted cuttings is being conducted in New Zealand and Australia for Pinus
radiata t in the United States for Pseudotsuga menziesii, in Nigeria for Triploohiton and
in the Congo for Eucalyptus spp.
Size and Quality of Planting Stock
There is a considerable range in what is considered the optimum size of seedling
for planting. The optimum size varies depending on: 1) whether the seedlings are bare-
root or container-grown, 2) the species and 3) the characteristics of the planting site.
It is generally agreed that plants with a well proportioned root/shoot ratio
represent good planting stock, but except under detailed specified conditions it is
difficult to define an optimum root/shoot ratio. A generalized ratio based on length
might vary between 0.4 and 1.0, although a root/shoot weight ratio would give a more
accurate measure of balance. Stem diameter and height ore other criteria for grading
planting stock that might allow the setting of minimum acceptable limits. In the United
Kingdom for example, seedlings are graded by height and diameter, with bare-root conifers
generally varying from 15 to 22 cm minimum height and from 2.5 to 4*0 mm minimum stem
diameter (Aldhous, 1972)* Such plants are usually from one to four years old and may have
spent one or two years in transplant beds. In the tropics plants are ready for planting at
between 3 and 12 months. Experience and research indicate that medium-size stock, for
example conifers between 15 and 40 cm, with a woody root collar often have a better
survival rate than smaller plants.
The morphological grading of planting stock must depend to a large extent on local
research and experience and the setting of local standards. Studies in the United States
have oast some doubt on the adequacy of such morphological grading as a survival index,
and research is currently being directed towards the determination of physiological criteria
and in particular the capacity for rapid root development following planting (Kozlowski,
1973).
-57-
In the case of tubed or potted stock, the maximum size for planting out is largely
determined by the size of the container. The larger the container the larger the plant
that can be grown in it, but the period is limited to that period free of harmful root
restriction. For euoalypts in the Sudan and Nigeria, plants are usually 20 to 30 om high
from root collar to tip. In Zambia there is a trend to smaller euoalypt plants 10 to 15
om high, and for pines 15 to 20 om is specified for standard tubes and 10 to 15 om for
minipots. Vtry small plants may be subject to frost heaving in temperate regions, whereas
excessively tall plants are liable to be blown over or loosened in the ground, and root
development may be restricted or inadequate to cope with the high transpiration demand of
a large top.
Planting stock should as far as possible have been hardened-off in the nursery
prior to planting, but this is not always possible with fast-growing species such as
euoalypts.
A further factor affecting grade of stock is the state of the planting site. It
is possible, for example, to successfully plant smaller seedlings on clean cultivated sites
than in weed-covered uncultivated land. A high standard subsequent weeding regime can also
compensate for smaller stock at planting.
Timing of Planting
In general the best time to plant is when the soil is moist and free from frost,
when atmospheric conditions are humid and evaporation rates minimal and if possible when
plant shoots are in a dormant state. Dry, sunny and windy days should be avoided. In
many of the cooler temperate regions the best planting time is in spring when ground
temperatures are above 4 - 5C. In the Australian temperate regions planting is mainly
during the winter; in California it is in the late autumn, winter and early spring.
Spring planting generally limits the period suitable for planting to about one month,
except for container plants for which the planting season may be slightly extended.
Delays in planting which prevent taking advantage of optimum periods reduce the degree of
success, and long delays may result in complete failure.
In some moist tropical or equable climates, planting may be feasible over much of
the year, but in other regions where there are pronounced wet and dry seasons, planting
operations should coincide with the onset of the period of regular and continuous rains
and should begin as soon as the soil has become sufficiently moist. In Zambia, for
example, planting is started when the soil is moist to a depth of 30 om. In East Africa
a formula has been evolved to determine the soil moisture buildup based on daily rainfall
and temperature readings (Griffith, 1957). Briefly, this method ascertains the daily loss
of moisture from the soil by evaporation and a measure of the daily gain from rainfall.
A running gain and loss account is kept, and when a certain amount of soil moisture has
accumulated, planting is commenced. The amount has to be calculated for each planting
locality and depends on type of soil, altitude, local probability of rainfall and the tree
species being planted. Such a procedure brings greater certainty into the decision of
when to start planting, but still requires judgement based on a knowledge of local rainfall
patterns.
In many savanna areas the optimum period for planting is only one month or less.
To achieve extensive planting programmes in such a limited period requires considerable
planning preparation and accurate calculation of probable planting dates. In Nigeria,
for example, Kowal (1975) estimated planting dates for a number of savanna stations with
Penman's formula based on reliable synoptic stations. By programming nursery and land
preparation to such planning dates, it should be possible to slightly advance or delay
planting to take advantage of actual favourable climatic conditions occurring either side
of the estimated dates.
-58-
The use of container stock oan extend the planting season, since the plants are
more tolerant of climatic variations, particularly dry spells, than bare-root stock.
Even in dryer regions planting oan be extended outside the normal planting season,
provided the plants are watered or irrigated until they are established.
Plant Spacing
As the spacing between plants varies with a number of often conflicting
requirements, the selected spacing may be a compromise between si Ivi cultural and managerial
objectives. Close spacing, for example, may be desirable to achieve early canopy closure
with consequent suppression of weeds and reduction in the weeding period, but if soil
moisture is a limiting factor at certain times of the year a wider spacing may be required
if stagnation of the plantation due to a moisture deficit is to be avoided* The early
takings-over of the site by the plantation crop is not only of consequence in suppressing
weed competition but also reduces any fire hazard at a stage when the crop is particularly
vulnerable. However, while a close spacing will produce early canopy closure, it may also
create a need for early and unsaleable thinnings.
Some of the factors influencing the ohoioe of planting distances are:
1) The growth rate of the species planted. Slower growing species
tend to be planted at closer spacing than faster growing species,
and for this reason spaoings in the tropics tend to be greater
than in temperate regions.
2) The growth form of the species planted. Some species have a very
branchy form and need to be planted closely to promote the form-
ation of a well-defined leading stem. Other species, including
many of those from the tropics, are self-pruning and oan therefore
be planted more widely apart.
3) The hazard posed by competing weed growth. Despite the fact that
close spacing reduces the time to canopy closure, it may well
increase the difficulties and costs of weeding. Mechanized weeding
requires a spacing between tree rows sufficiently wide to allow for
the passage of a tractor and implement. A distance of 2.8 m
between rows is considered a minimum spacing where weeding is
mechanized.
4) The availability of soil nutrients and soil moisture. In shallow
soils, or on sites with frequent rock outcrops, the spacing will
tend to be wider allowing more room for root development or it may
be irregular to conform with the distribution of soil pockets among
the rooks. In arid regions, soil moisture is often a limiting
factor and the general practice is to use fairly wide spaoings,
especially where inter-row cultivation is practised to promote rain
water retention.
5) The influence of drainage or irrigation works. The layout of drains
in wet soils or of the water channels in irrigated plantations oan
also influence the spacing of planting lines. For example, in
plantations on peat lands, where the trees are planted along ridges
turned up by drain ploughs, the spacing and the drainage pattern
have to be coordinated.
-59-
6) Future management. If it is policy to reduce the number of early
and often unsaleable thinnings wider spacing is recommended, as in
the case of some plantations of fast growing tropical conifers
where crown closure is delayed in the interests of promoting
diameter growth. The costs of high pruning the final crop stems
is an additional debit. On the other hand f closer spacing can be
adopted if the production of fuelwood, small diameter poles, or
pulpwood is the object of management. In out-over tropical high
forest, wide spacing of planting lines coinciding more or less
with final crop espaoement has been adopted leaving inter-bands of
natural regrowth, and in taungya plantations the tree crop spacing
has to be sufficiently wide to allow the cultivator to carry out
his cropping over a reasonable period.
7) Financial aspects. Costs for plants and labour tend to increase
with decreasing planting distances, but on the other hand, costs of
weeding tend to increase with wider spacing.
Organization of Planting Operations
General Layout
The general layout of the entire plantation area with the planned subdivisions,
roads, rides and drains will have been delineated on the plantation maps, as noted in
Chapter 6 on plantation planning.
The area programmed for planting in any particular year will normally be made
ready for planting prior to the estimated planting date. Compartments will be surveyed
and delineated by roads, rides, tracks or firebreaks. All corner and intersection points
should be marked by plainly visible, more or less permanent beacons. An essential
feature is that there should be sufficient all weather roads in the planting area to
allow the transport of plants and access for labour to carry out planting and subsequent
operations. Where mechanized operations, such as weeding, are planned, sufficient space
should be left for tractor turning, not necessarily at the end of each compartment but at
that boundary which might serve as the end of weeding runs.
Marking or Pegging for Planting
With the possible exception of plantations on hilly ground where soil conservation
works following the contour are necessary, planting should wherever possible be in
straight lines. This is mainly to facilitate weeding operations after planting, and is
equally important whether hand, mechanical or chemical weeding is employed. Plants which
are out of line (and often obscured in weed growth) are more liable to be out or injured
during weeding. The maintenance of straight lines is not of the same consequence where
there is no subsequent weeding.
Except up or down hill, straight line planting is not of course possible on sloping
ground under conditions where contour soil or water conservation works form part of the
site preparation work. On such sites planting lines normally follow the direction of the
contour banks, steps or ridges.
There are many variations in marking out or pegging planting lines, but for
straight line planting squaring is the most common. Commencing at the corner of a
compartment and using a compass or optic square , the corners of an exact square are laid
out and pegged. The sides of the square will be the length of the planting chain and will
be an exact multiple of the plant spacing. Planting chains are tagged at the plant
spacing and are generally from 30 to 80 m long. From the outer pegs of the original
-60-
square two base lines are laid out at right angles, placing pegs in the ground at the end
of each planting chain length. Returning to the starting point , and using the chain f the
corner of other squares are sighted in from the original pegs until the entire area is
squared* Adjacent compartments should have their pegging aligned to that of the first to
facilitate subsequent operations* It is important to carry out periodic checks to ensure
that the distance between pegs is being accurately maintained* Chains should be checked
for stretching daring the operation* At any irregular compartment edges, with sections
less than the participating chain length, a peg should be inserted at that last planting
tag which comes within the planting area* Where mechanized weeding is envisaged, the base
lines should leave a margin of 2 m or more between the edge of the road and the planting
line to allow for weeding. Such squaring is usually adequate for subsequent pitting or
planting operations, but in some areas the tagged planting chain is also used to peg the
plant spacing along the two opposite sides of each square*
Another method of marking is to use a light tractor fitted with a boom carrying
tines at set intervals which mark the planting lines by scratching parallel furrows in
the soil. When repeated at right angles the intersections mark the planting spots. This
method depends on the tractor driver's ability to steer a straight course on his sighting
beaoon f and is only feasible on relatively level surfaces free of obstructions. Similarly,
where sub soil ing is carried out during preparation work, the planting lines correspond with
or are close to the furrows of the subsoiler tines.
In oases where cross cultivation or weeding by tractor and implement is prescribed
for post-planting tending work, it is important to ensure that the planting pegs are in
straight lines in two directions.
Where pit planting methods are planned, pits may be dug soon after pegging out, or
may be done at planting time. Where notching methods are used, it is common for the
planters to pace out planting distances as they plant, a skilled planter being able to
maintain the planting line by eye. Mistakes, however, can be made if the planter is
careless or tired, so that where inter-row tending by mechanical means is prescribed it is
always advisable to take the trouble to peg or chain planting lines.
Organization of Planting Work
The sequence of all operations preceding the actual planting must be so timed
that planting can begin immediately site conditions become suitable. If, as has been
noted, the planting season is relatively short, it becomes important to ensure that
adequate supplies of planting stock are distributed at depots easily accessible to the
planting area.
The success or failure of a plantation depends to a great extent on the skill of
the planters. If skilled men are not available for this work it will be advisable to
provide training before planting begins.
The forester or supervisor in charge should ensure deliveries of plants from the
nurseries in such quantities as to keep the planting gangs fully at work. This requires
a knowledge of 1) the average labour planting rate, 2) the planting method used, 3) the
size and type of plants (bare-root or container), 4) the terrain and soil type and 5)
the skill and experience of the planters.
Since planting stock is liable to deterioration from exposure, the forester should
gauge deliveries so that stock is planted during the same day as delivery, but usually
some surplus stock has to be carried to provide for emergencies. Stock not required for
immediate planting should be protected against exposure by "heeling in" of bare-root
plants or by placing container and ball-rooted plants in depots where the plants can be
shaded and watered. The roots of all plants should be kept moist. The feasibility of
treating the shoots or the roots of planting stock with chemical ant i-t ran spirants is
under investigation and trial in many countries.
-61-
In exceptional oases, for example, where plants need to be delivered to the
planting site before snows block road ooramunioatione, the establishment of temporary
storage nurseries should be considered.
The means of distribution of planting stock from the main off-loading or delivery
point to the actual planting areas depends largely on the terrain, the transport available
and the type of plants* Bundles of bare-rooted plants can be carried to the site by men,
by pack transport or by four-wheel-drive vehicles, depending on the terrain. The plants
are subsequently collected by planters who refill their bags or containers from local
depots spaced out at short intervals over each day's planting area.
Container plants are normally despatched from the nursery packed in wooden trays
or boxes of standard dimensions conveniently handled and carried by one worker. The
number of plants per container may also be conveniently matched to the number of plants
required between squaring pegs. The trays are loaded on tractor trailers for transport
to the planting areas or f in very steep terrain where animal transport is used, on
specially designed saddles. The trays are off-loaded at intervals along the planting
lines ahead of the planting gangs. The carrying capacity of lorries and trailers is
greatly increased if the lorries and trailers are fitted with shelving allowing trays to
be stacked in tiers.
Multi-level tractor trailers of various sizes oan be constructed for
transporting tree seedlings from the nursery to the planting sites. The
trailer of limited capacity shown here is suitable for planting small areas
near the nursery and for replacement planting; for more extensive areas,
greater transport efficiency can be attained by using larger trailers.
(Courtesy D.A. Haroharik)
-62-
Planting Methods
Proper attention to detail in planting is often of greater importance than the
method itself* It has been indioated (Wakely, 1954) that depth of planting and proper
olosure of the planting hole are the more critical factors affecting survival*
Hand Planting
The two main manual techniques are notching and pit planting* Notching is used
only with "bare-root plants. In its simplest form it consists of cutting a slit in the
ground with a spade or mattock, opening the slit wide enough to insert the roots of the
plant, and finally closing the slit by pressing with the foot or heel* Variations consist
of the T notch and the + notch. Both require a double slit, which takes longer unless a
special tool is used f but the plant roots can be better spread than in the simple notch
which tends to set the roots in one plane* When planting on turf or peat ridges and
mounds, the slit should penetrate the ridge only as far as the original surface of the
ground, as experience indicated that survival rates are less satisfactory if the roots
are set deeper than this.
Dibbling is a variant of notching in which a planting bar or dibbling stick is
driven into the ground creating a slit into which the plant is inserted and firmed by
driving the bar into the ground beside the plant and levering the soil lightly against
the plant. Dibbling is used for planting bare-root stock, unrooted cuttings, sets and
sometimes for stump plants.
Ball-rooted or container stock can only be planted in pits. Pits are very often
of much greater dimensions than the ball or corrtainer. It has been suggested that larger
pits may have beneficial results in uncultivated sites as this provides a greater zone
for early root penetration. In general, however, a pit that will readily accommodate the
seedling roots is adequate.
For container- raised seedlings, manual digging of the planting hole is the
standard technique. A hoe, such as that shown here in use near Ain Beida,
Algeria, is a suitable tool. (FAD photo)
-63-
Pits are usually dug with types of spade or a broad-bladed mattook f the top soil
being kept separate from the subsoil, so that it oan be filled in first at the time of
planting* In some countries pits are excavated some months before planting to allow the
spoil as well as the exposed sides of the pit to be moistened by rainfall* On sites that
have been already ploughed this is not so necessary, and the digging of pits is then
carried out just ahead of or at the time of planting.
Pits oan also be dug by power-driven borers or augers. These are either hand-
oarried or tractor-mounted; the latter are driven from the power takeoff. Tractor-
mounted augers oan dig about 10 times faster than a man, but their operation is
restricted to flat areas, and they are costly to operate. Tractor-mounted borers are,
however, very suitable for planting poplars and similar tall stock, for which deep holes
(0.5 m or more) are needed. One disadvantage of mechanized borers is the danger of
glazing or compacting the sides of the planting pits.
All types of planting stock oan be planted in pits. When bare-root stock is used
the plant is held in the pit so that it will be set at about the same depth or not more
than 3 cm deeper than it grew in the nursery, and the roots are spread out freely. Using
the other hand, half of the pit is filled and packed with moist soil. The remainder of
the pit is then filled, packed and consolidated. At the end of the operation the soil in
the pit should be level or slightly higher than the surface of the ground to allow for the
earth sinking after rain or watering. For this reason it is usual to bury the root collar
a few centimetres, so that after consolidation it remains at or near the surface of the
ground. If the root collar is exposed, survival may be jeopardized. In dry regions it is
usual not to fill the pit to ground level so that a depression is left to collect rain
water or dew, but in heavy soils with low percolation rates, such depressions oan retain
water for several weeks, causing localized waterlogging resulting in the death of the
plant.
Deep-planting, whereby the plant is almost completely buried, leaving only the tip
of the shoot exposed, is practised in arid regions on driftsand or loose textured soils
where the top layers of the soil are liable to dry out completely during the summer. Such
soils frequently have a moist layer below the capillary lift zone (the layer to which
ground water is lifted by capillary forces), into which the roots must be planted.
When planting container stock, a pit just slightly larger than the container is
made with a trowel, dibbler or mattock. It is usually necessary to remove the plant from
the container, or to slit or out it before planting. For full removal of a polythene pot,
a knife or razor is used to slit the pot, the bottom is torn off and the remaining tube is
slipped off as the seedling is placed in the pit. Partial removal is similar except that
some 7 cm of the upper tube is left around the soil cylinder. This forms a collar, of
which approximately 3 cm are left above the ground after planting. This practice is
common in areas where termites are a problem, such as in African savannas. The object of
leaving the collar is to prevent field soil covering the insecticide-treated pot soil
during weeding. Such untreated field soil oan serve as a bridge for termites to attack
susceptible species* Once the seedling is in the pit, the excavated soil is used to fill
any gaps or holes and the plant is thoroughly firmed in by foot pressure.
The soil round all newly planted stock should be firmed by trampling to avoid
large air spaces from forming in the soil and to bring the earth into intimate contact with
the roots. Firming also minimizes damage caused by wind which oan shake the plant and
disturb the roots in the period between planting and consolidation of the soil. Very tall
planting stock is much more liable to wind disturbances, and where wind is a problem it
may be necessary to drive wooden stakes firmly into the ground beside the plant and to tie
the stem to the stakes. Staking newly planted poplars, which are often 2 to 3 m in height,
is common practice.
-64-
Mechanised Planting
Planting machines are at present used mainly with bare-root stook. If correctly
adjusted and used they generally give good survival f minimize root distortion and cover
the ground quickly (e.g. up to 12 000 plants and more per machine daily), but they can
only be economically used over large areas and are limited by topography and vegetation.
By handling mainly bare-root stock, mechanised planting is mainly confined to temperate
climates, but research and development is being carried out to develop planting machines
for small container plants and other machines for poplar sets or cuttings.
Planting machines are either mounted on or towed by a tractor. Towed planters
are the most widely used, but heavier mounted planters tend to be more effective on
difficult sites and slopes. The basic machine operations are: 1) the making of a vertical
cut in the ground, 2) opening up the out to receive the seedling and 3) closing the cut
and firming the soil around the plant. These *sic operations may be supplemented by
devices for removing vegetation, by water sprays or fertilizing systems or by a timer for
mere accurate plant spacing. The vertical out can be made by a knife edge or a plough
si ire but the most common tool is a straight or curved coulter disc, which has the
advantage of reducing the pulling power required, of riding over obstructions and of
cutting most soils easily. The opening device or "plant shoe" consists of a slotted
piece of steel plate, with the front edge pointed and designed to lead into the out and
the back end open to allow the seedling to pass through. An operator in a seat or saddle
situated behind the coulter disc feeds seedlings into the planting shoe at the required
spacing. The final operation of closing the slot is achieved by two inclined rotating
wheels, normally fitted with pneumatic tyres. Supplies of planting stook are carried in
cradles on the machine within easy reach of the operator, and precautions are taken to
prevent drying out of the seedlings.
Most planting machines, such as this one in operation in the U.S.A., are
designed to handle bare-root seedlings. Development of mechanical planters
suitable for container stock is now underway. (Courtesy K.P. Karamchandani)
-65-
High productivity rates can be attained by mechanical planting on areas of level
terrain and few obstructions, such as these grasslands in Venezuela which are
being converted to Pinus oaribaea. (Courtesy B.J. Zobel).
Replacement Planting
Replacement planting, "in-filling" or "beating^up" are the terms used for replacing
dead plants in a recently created plantation. The aim in all planting should be to have no
replacement to do, but inevitably there axe some failures due to such factors as poor
planting, drought, frost or breakage. When deaths do occur, the plantation has to be
assessed to determine whether the remaining trees are sufficient to establish a satisfactory
crop* The time of sampling for replacement planting generally is related to growth rates
and for fast growing species would be within weeks or a few months of planting, whereas with
slower growing trees six months to a year and sometimes more after planting would be
adequate.
What constitutes a satisfactory survival varies in different regions. In California,
for example, for pine timber plantations planted at 3 m x 3 m a 46% survival at five years
constitutes an acceptable stand. This is, however, a minimum standard and higher stocking
survival is desirable (Schubert and Adams, 1971 ) In Nigerian savanna, a survival of 90$
is desirable for euoalypts and pines planted at 3 m x 3 m, but when this falls below 80$ an
assessment is needed to determine whether replacement or total replanting is required. With
high mortality the object of taking over the site may not be achieved, and a heavy influx of
weeds can have a further deleterious effect n remaining trees and may create an unaccept-
able fire hazard. In Britain it is rarely considered worth beating-up a plantation if
survival is 80$ or better.
-66-
The distribution of casualties oan also affeot the need for replacement planting.
For example | where failures are evenly distributed the average survival figures may be
acceptable, but this may not be the case where deaths occur in groups or patches. To be
effeotive 9 replacement planting must be carried out as soon as reasonably possible after
planting y and rarely more than a year later, even with slow growing trees. Consequently
it is important to carry out this operation with considerable care and with high quality
seedlings at least as good as the original stock.
Serious failures, although sometimes attributable to unusual climatic conditions,
are often due to errors in judgement or technique during the establishment process, for
example, selecting the wrong site or species, inadequate site preparation, use of poor
planting stock, careless handling, excessive exposure during transport, poor planting,
pest or disease depredations or neglect of maintenance. Any serious failure requires
careful investigation to determine the possible causes, so that remedial action oan be
taken in the future and before any replacement planting.
Fertilizers and Myoorrhizae
Soil nutrient Status
Trees, u other plant*, require from the moil an adequate supply of all thirteen
essential elements for healthy vigorous growth. The*e elements are the macro-nutrients!
nitrogen, phosphorus, potassium, nagneaiua, oaloium and sulphur; and the micro-nutrients
or trace eleents boron, copper, iron, zinc, manganese, molybdenum and chlorine. Unthrifty
growth or even failure nay indicate deficiencies of one or more of these nutrients, but poor
growth may be due to other oouaet including!
1) Excess or deficient soil moisture,
2) Inadequate soil aeration,
3) Pathological condition (due to attack by insects, fungi,
bacteria, viruses or nematodes) or
4) Soil conditions which inactivate the soil flora or fauna.
If soil nutrient deficiency is suspected as causing poor growth, the soil should
be analyzed to discover which elements appear to be in deficit. Foliar analysis is
another diagnostic technique which is being more frequently used. Local field tests
should confirm the composition and quantity of fertilizer and the methods and times of
application required to remedy the deficiency and give healthy growth.
The elements most commonly in short availability are phosphorus and nitrogen, and
in experiments in which these elements were added increases of growth were most often
obtained. However, nitrogen fertilizers in the absence of adequate phosphorus, either in
the soil or in the fertilizer, have occasionally been deleterious and, even with sufficient
phosphorus present, they do not always give positive responses unless there has been
adequate rainfall and generally moist conditions prevail. Potassium rarely seems to give
positive responses. In dry zones the application of fertilizers sometimes causes
increased mortality in newly-planted areas, possibly due to high concentrations of the
fertilizer salts in the soil solution if adequate rainfall does not follow* The worst
damage is to be expected after light rain followed by a dry spell, and where rains at
planting time are unreliable it may be advisable to defer fertilizer application until
the rains have become established and there is no danger of the soil drying out (Laurie,
1974).
-67-
Fertiliier Applioation
The main reasons for applying fertilizers arei
1) To allow the planting and grovrth of selected trees on sites where
adequate tree growth is not possible due to general lack of
fertility or to specific nutrient deficiencies and
2) To accelerate the growth rate of trees after planting so as to
increase the chances of survival and to shorten the establishment
phase.
Advances in the science and technology of forest fertilization have been fairly
rapid over the past twenty years. The identification of phosphorus and nitrogen deficiency
over extensive areas of plantation land have been promptly and effectively dealt with by
the application of fertilizer technology adapted from agriculture (Bengston, 1973). Types
of phosphorus and nitrogen fertilizers suited to particular forestry situations have been
and are being developed.
The timing of fertilizer application is important. For some species and soils,
addition of fertilizers at the time of f or soon after, planting may be beneficial; in
other cases, fertilizers are applied years after planting. Numerous fertilizer experiments
have been carried out, often with conflicting results. This is perhaps to be expected when
the great variety of soils and of species is considered, and it is difficult to fomilate
generalized recommendations either for species or recommendation*.
Fertilizer application is often by hand, but an extensive range of equipment has
also been evolved, particularly for large-scale application. The types of equipment include:
1) Tractor mounted spreaders using air blowers or mechanical spreaders
to broadcast fertilizers and lime,
2) Tractor mounted applicators which can meter and selectively apply
fertilizers simultaneously with either site preparation or planting
operations and
3) Aerial application by fixed-wing aircraft or helicopter.
Aerial application is excellent for large areas. The technique was advanced rapidly
by the development of special disposal reservoirs or canisters which can be quickly fitted
and removed. Since 1974* however, the steeply rising costs of fertilizers have encouraged
new research and development of equipment and techniques which aim to economize on the
amounts of fertilizer used by effecting more precise placement.
Tree Response to Fertilizers
Fertilizer application to remedy deficiency conditions can often produce remarkable
results. In many savanna areas, for example, euoalypts, in particular Eucalyptus grandis.
are found to be very sensitive to low fertility, especially to boron deficiency. The
symptoms of boron deficiency are leaf deformation, serious die-back during the dry season
and frequently death. Experiments in Zambia, Nigeria and elsewhere have confirmed the need
to apply boron fertilizer in such areas, and in Zambia heavy standard applications of from
57 to 144 g of borate (14$ B) per plant are given, the quantity depending on site. Boron
deficient crops will produce no saleable yields but E. grandis with borate often reaches a
mean annual increment of over 25 m3/ha. ~
-68-
A great deal of work has been done on fertilizer application to pines, particularly
phosphates (Waring, 1973), and some of the findings have fairly wide application. With
P. radiata in Australia it was found that for maximum production it is necessary to
fertilize at planting and to control weeds. Early responses to fertilizer were still
evident at canopy closure and increased with time up to at least 25 years without additional
stimulation. Delaying fertilizer application oan appreciably reduce productivity. The
quantity t time and type of fertilization! type and quality of site preparation and degree
of weed control interact to influence early response and consequently total production.
Optimizing these various factors offers good management an opportunity to maximize increment.
In Nigeria, an application of 114 g of phosphate was found to increase both survival and
growth of P. oaribaea (Jackson, 1974), and in Western Australia zinc fertilizers improved
the growth~of P. pinaster plantations.
Nitrogen deficiency is a limiting factor on some sites, often on abandoned and
degraded fields or in areas of drifting sand* The addition of nitrogen-rich compound
fertilizers, urea or organic manures is required to get the trees away to a good start on
such sites* There is, however, a danger of acidifying certain soils by excessive
application of urea or other nitrogenous fertilizers. Sometimes nitrogen-fixing tree crops
such as alders (Alnus spp.), and many leguminous species are grown either as pioneer nurse
crops or as an understory in admixture with the main tree crop. Lucerne and other herb-
aceous legumes grown as green manure can also be used to raise nitrogen availability in the
soils.
Myoorrhizae
Most forest trees have mycorrhizal fungi associated with their roots and it is
thought that trees will not thrive unless satisfactory symbiosis with one or more kinds of
myoorrhizae has developed. As a result, the practice of inoculating nursery soils with
rnyoorrhiza-infeoted soil from forests or plantations has become widespread. Instances have
been reported from East Africa and from Latin America of unthrifty plantations of tropical
pines which have been restored to health and vigour following soil inoculations by cultures
from areas where the pine is indigenous or has become well established. Many species of
Arauoaria are reputed not to thrive as exotics unless both the eoto- and endotrophio forms
of the mycorrhizae normally associated with their roots are present in the soil.
Recent research has shown that in very fertile soils tree roots tend to have a much
more limited association with raycorrhizae or none at all; accordingly the application of
fertilizers also seems to reduce the dependence on symbionts. It has not yet been fully
established whether the mycorrhizal association is essential for the development of trees,
or whether the association is developed by the tree as a device for increasing nutrient
availability in less fertile sites. In recent years, much research has centred on
comparing the effects of different species of mycorrhizal-forming fungi, often with notable
success. Marx and Bryan (1975), for example, have shown that Pinus taeda seedlings
inoculated with Pisolithus tinotorius grew better on harsh, infertile, disturbed sites with
periodic high soil temperatures tnan did seedlings inoculated with Telephora terrestris,
the more common and typical pine nursery inoculum in the southeastern United States. P.
tinotorius also holds promise as a pine inoculum suited to high tropical temperatures;"" in
Nigeria, Momoh et al. (1977) found it was able to withstand higher temperatures than
Hhizopogon luteolus. the general myoorrhizal fungus in use.
TOTOINQ OPERATIONS
Tending operations are those required to promote conditions favourable for the
survival of the plants after planting and to stimulate a healthy and vigourous growth until
the plantation is established. On most plantation sites, tending is mostly concerned with
preventing the plants from being suppressed by competing weed vegetation. Other tending
operations are watering or irrigating the plants in dry areas; in sons oases pruning or
tree shaping nay also be necessary.
-69-
Weeding
Weeding in plantations may generally be defined as a cultural operation eliminating
or suppressing undesirable vegetation whioh would t if no action was taken, impair the
growth of the plantation tree crop. Weeds compete with the tree crop for light, water and
nutrients, and weeding should increase the availability of all or the most critical of these
elements to the planting crop. The main objective of weeding is to promote the growth and
development of the plantation crop, while keeping the costs of the operation within
acceptable limits.
The main factor affecting the intensity and duration of weeding is the interaction
between the tree crop and the weeds. On some sites the tree crop would eventually grow
through the weeds, dominate the site and become established; and on such sites the main
function of weeding is to increase crop uniformity and speed up the process of establish-
ment. On other sites, the type or density of the weed growth is such that in the early
stage of a plantation it will suppress and kill some or all of the planted trees, and in
such areas the main purpose of weeding is to reduce mortality and maintain an adequate
stocking of trees to establishment. When the interaction between the tree crops and weed
growth has been determined and understood, plantation management will have some under-
standing of the general principles of weeding and of the options open in relation to
frequency and duration of weeding; some of these are:
1) Most crops would benefit from a form of total weeding, but very often
this is neither feasible nor can it be economically justified.
2) With tree species to some degree tolerant of weeds, a range of weeding
intensity may be applied down to the level that will just achieve
satisfactory establishment.
3) Tree species intolerant of weed growth require high intensity weeding
until the tree crop has taken over or dominated the site.
Clean weeding is not confined to the tropics. In northern Italy, for example,
industrial plantations of Pinue strobus are clean cultivated mechanically during
the establishment phase. (Courtesy Institute Nazionale per Piante da Legno, Torino)
-70-
Other principal f motors affecting weeding are rainfall, temperature f initial orop
pacing, size of plant s, rates of growth, wed species and density, ability of the weeds
to regenerate, such site features as fertility, moisture availability and slope and the
skill of the manpower available for weeding.
Methods of Weeding
The main methods of weeding are suppression and elimination; both oan be done
manually, mechanically or by ohemioal techniques. Weed suppression is effected by
physically beating down or crushing the weeds or by cutting or so reef ing the weeds back at
or above ground level* Weed elimination is achieved by killing the weeds, either by
destroying the whole plant by cultivation or by the use of chemicals. Weeding may be total
or partial; the main partial methods being spot or line weeding*
Weed Suppression
The simplest method of manual suppression is to trample or beat the weeds down,
away from the plantation trees* This operation may be mechanized by using a tractor-towed
roller, but such an implement cannot operate too close to the tree orop*
The most common manual method of weed suppression is to out them back using a
variety of cutting tools such as sickles, brush hooks and scythes* In many countries cane
knives or mate net ee are used, and although such tools may not be ideally suited for
particular vegetation types, they are used with great skill and the labour need not adapt
to a change of tool*
There is a wide range of mechanised cutting wteders, suoh asi
1) The portable brush outter, as noted in Chapter 1}
2) The pedestrian controlled two wheeled machines suoh as the
reciprocating bladed autosoythes or similar machines with
rotating blades or flails;
3) Tractor powered machines for brush cutting, mainly rear-
mounted and operated from the power take-off:
a) horizontally rotating ohain swipe machines,
b) horizontally rotating blade machines and
o) vertically rotating flail machine B.
Weed Elimination
Weeding by cultivation generally requires that the weeds, including the roots, are
dug out of the soil and are either laid on the surface or are chopped up and worked into
the soil* In addition to eliminating weeds, suoh cultivation may increase rainfall
percolation and reduce evaporation from the soil, features which are of considerable
significance in certain areas with a marked dry season*
Manual weeding cultivation is done mainly by long handled straight hoes or, in the
tropics, by shorter handled recurved hoes* The operation is usually more effective if the
hoe is used for actual cultivation involving turning over of the soil, rather than scraping^
off of the weeds* As total manual cultivation requires high and costly labout inputs (e.g.
Nigeria 25 to 30 man-daye/ha) the operation is usually confined to spot or line weeding*
In spot weeding a circular area 1 - 2 m diameter is hoed around the treesf in line weeding
a strip about ene metre wide is hoed along the plasvtia* line. Weeding eosts are reduced in
-71-
taungya plantation*, where the farmer in tending his crops gives fall or partial weeding
cultivation over the area during the growing season*
In certain areas with a marked dry season, suoh as savanna, it has been found that
spot or line weeding is insufficient to give adequate plantation survival or growth, and a
system of mechanized total cultivation on suitable flat or gently sloping sites has been
developed. Total cultivation for large-scale plantations involves mechanized interrow
weeding and supplementary hand weeding close to the plants* The only totally mechanized
cultivation is the pre-plan ting harrowing which although classed as a land preparation
operation, also serves the same purpose as a weeding carried out immediately before
planting*
There is a wide range of mechanized equipment for weeding cultivations including
powered two-wheeled or oxen drawn cultivators for small-scale operations; the main
weeding equipment for larger scale work includes:
1) Agricultural tractors with rear-mounted heavy duty offset
disc harrows and
2) Agricultural tractors with rear-mounted rotavators,
The disc harrows are widely used and, except in areas of exceptionally heavy weed growth,
have proven satisfactory in practice. The rotavators also give good cultivation and can
deal with heavier weed cover than harrows, but being more sophisticated than harrows, are
more prone to damage, unless operated with care and 'skill.
When interrow weeding is in one direction only it is supplemented by line weeding,
when in two directions it is supplemented by spot weeding. Line weeding requires a labour
input of some 60$ more than spot weeding. Mechanized cross weeding, however, results in
some 6&fo of the interrow area being cultivated twice* One major disadvantage of cross
weeding is that the tractor has to cross at right angles the furrows made earlier by the
harrow, and the consequent pitching and shock loading can seriously increase wear and
tear on the unit.
Total and partial weeding using chemical herbicides have and are being extensively
developed. The types of herbicide commonly used for weeding are included in those listed
for site preparation in Chapter 1. The essential feature is that experiments are necessary
to determine types of herbicide and methods of application, suited to particular plant-
ation species and sites. The main methods of application include:
1) Hand operated knapsack sprayers,
2) Motorized knapsack mist blowers,
3) Granular herbicide applicators,
4) Tractor-mounted mist blowers and high volume sprayers,
5) Ultra low volume sprayers and
6) Aerial application.
The selection of type of herbicide application is largely a matter of so ale and
experience. The development of ultra low volume sprayers has generally widened the
possibility of herbicide use. Aerial spraying is feasible for some large-scale plant-
ations; it is extensively used, for example, in New Zealand where some 25 000 ha, or 8*7%
of the annual weeding programme, was done by this method (Chavasee and Pitzpatriok, 1973)*
-72-
A wheeled tractor with a re axmounted disc harrow is used for interrow weeding
young pine and eucalypt plantations in African savannas. (Courtesy T.O* Allan)
-73-
Types of Weeding Regime
In -temperate regions where partial weeding by cutting or ohemioals is done, it is
common practice to do summer weeding onoe each year until the plantation trees top the
weeds* This oan involve a weeding programme of from two to five years. Poplars, for
ezample 9 require weeding in the two to three years following planting. A common temperate
practice is to out the vegetation and lay a mulch of 1.2 to 2 m around the tree each
season.
In savanna regions a common mechanized schedule for eucalypts would be:
Time of Operation
First year regime (age to 8
months), during the rains
Second year regime (age 12 to
20 months)
and Number of Weedings
6 mechanized interrow weedings
in alternate directions supple-
mented by 5 spot weedings
1 to 4 mechanized interrow
weedings y with no hand weeding
necessary
A similar regime would be used for pines but the duration would be three to five
years instead of two. Both euoalypts and pines in the tropics grow during the dry
season at which time the quantity of soil moisture is restricted and the clean weeding
regime should increase the water availability to the plantation trees, particularly during
the initial year when root development is taking place.
Watering and Irrigation
Plantations in arid and serai-arid regions often need watering periodically during
the first growing season to obtain a satisfactory survival rate. Watering should begin
sometime after the cessation of rains when the moisture content of the soil has fallen to
near the wilting ooeffioient and should be repeated at intervals until the onset of the
next rains. Before each watering the trees should be hoed clean of weeds and a shallow
basin made round the stem of each tree. Where evaporation is high, a heavy watering (20
litres or more per tree) at relatively long intervals is more effective than more frequent
light waterings.
Watering is usually an expensive operation, especially on terrain too steep or too
rough for the passage of tank vehicles so that pack animals are required to carry drums of
water to the plantation site. Watering is uneconomical for large plantations, especially
if the souroe of water is at some distance away from the plantation, but it may be
justified in the oase of small amenity plantations or for establishing roadside avenues.
In many semi-arid countries, regular cultivation and weeding, especially during the first
growing season, has proved sufficient to conserve enough soil moisture for satisfactory
survival of the plants, obviating the need for watering.
In the oase of irrigated plantations, regular periodic irrigation of the whole
plantation is the principal routine tending operation, and may continue until the end of
the orop rotation. Irrigation channels need weeding at intervals to prevent weed growth
impeding flow rate. Spraying channel banks with herbicides, repeated at fairly frequent
intervals before the weeds grow too high, is an effective method of control. Irrigated
plantations are discussed more fully in Chapter 4.
-74-
Pruning and Shaping
With the exception of very widely spaced or ope, pruning ie not a normal operation
during the establishment phase* However, with certain epeoiee of tropical pine, for
example, Pinus keeiya and P. oooarpa, a basal pruning may be necessary to remove adventit-
ious and undesirable branches at ground level Occasionally pruning may also be carried
out not so much to improve the quality of the timber, but to allow access or to reduce the
possibility of fire spreading from ground level to the crown*
Tree shaping operations, including the excision of double leaders, are practised
in certain plantations, particularly those grown from stumps or cuttings* Such work may
very often be combined with climber cutting operations*
The early pruning of side branches and adventitious branohlets is customary in
wide-spread poplar plantations where the trees are expected to provide peeler lo^s for
match-making or veneers. Normally the boles are clean pruned up to one-half the total
height of the stem for the first five years, thereafter gradually reducing the crown
proportion to about one third of the total stem height* Adventitious branohlets, which
tend to appear each spring on the pruned section of the bole, are trimmed off as soon as
possible after their appearance* Pruning of larger branches is best carried out in the
spring before the sap rises j this also appears to accelerate occlusion of the wounds.
Pruning wounds or bark damage caused by weeding operations can be treated with formulae
tions of lanoline plus indo lace tic acid or lanoline plus Agrosan (an organo-mercuric
chemical) which hasten occlusion*
BIBLIOGRAPHY AID R
Aldhous, J.R. Nursery practice* London, Her Majesty's Stationery Office* 184 p.
1972 Forestry Commission Bulletin No. 43.
Allan, T.Q. Observations and studies of planting methods for forestry plantations in
1973 the savanna regions of Nigeria* Savanna Forestry Research Station, Nigeria.
14 P* Project Working Document NUR/73/007*
Appelroth, S.E. Work study aspects of planting and direct seeding in forestry* Jn
1974 IUFRO Symposium on Stand Establishment, pp. 202-273* Wageningen, The
Netherlands*
Bailly, C* et al* Fertilisation dee plantations de pins a Madagascar* Revue Bois et
1974 Forlts dee Tropiques no* 138 s 13-32.
Bakshi, B.K. Kjrcorrhiia - its role in man-made forests* JLn Proceedings of FAO World
1967 Symposium on Man-Made Forests and their Industrial Importance, Vol. 2,
pp. 1031-1042. Rome, FAO.
Ball, J.B. Plastic containers and ooiling roots* Uhasylva, Vol. 28(1), No* 111 s 27*
1976
Balmer, W.K., and Williston, H.L* Guide for planting southern pines* Atlanta, Georgia,
1974 U.S*A*, U8DA Forest Service, State and Private Forestry. 17 p*
BKrring, U. Treatment of young stands t ohemioal weed control* Jn Proceedings of IUFRO
1974 Symposium on Stand fctablishment, pp. 377-406* Wageningen, The Netherlands*
Binns, W.O, Fertilisers in the forest i a guide to materials* London, Her Nfcjesty's
Stationery Office. 14 p* Forestry Commission Leaflet No* 63*
-75-
Bengston, QW. Fertilizer use in forestry! materials and methods of application* ^n
1973 Proceedings of the PAO/IUPRO International Symposium on Forest
Fertilization, pp. 97-153. Paris, Ministfcre de l t Agriculture.
Ben Salem, B. Root strangulation! a neglected factor in container grown nursery stock.
1971 Berkeley, University of California. Thesis.
Blatchford, O.N. (ed.). Chemical control. The Entopath News, October, 1976. British
1976 Forestry Commission. 88 p.
British Forestry Commission. Influence of spacing on crop characteristics and yield.
1974 Forestry Commission Bulletin No. 52.
Brix, H., and van den Driessche, R. Use of rooted cuttings in reforestation. Victoria,
1977 Canada, British Columbia Forest Service/Canadian Forestry Service. 16 p.
Joint Report No. 6.
Brown, R.M. Chemical control of weeds in the forest. London, Her Majesty's Stationery
1975 Office. 65 p. Forestry Commission Booklet 40.
Chavasse, CGR, and Fitzpatrick, J. Weed control in forest establishment in New Zealand.
1973 Proceedings of the Fourth Asian-Pacific Weed Science Society Conference,
Rotorua, New Zealand, p. 267-273.
Cooling, EN, and Jones, BE* The importance of boron and NPK fertilizers to Eucalyptus
1970 in the Southern Province, Zambia. East African Agricultural and Forestry
Journal, October, 1970 i 185-194.
Crafts, A.S. Modern weed control. Berkeley, USA, University of California Press.
1975 440 p.
Crowther, RE Guidelines to forest weed control. London, Her Majesty's Stationery
1976 Office. 7 p. Forestry Commission Leaflet No. 66.
Donald, DG.M Planting of trees in polythene bags. Letter to South African Journal of
1968 Forestry, No. 67.
Everard, J.E Fertilisers in the establishment of conifers in Wales and southern England.
1974 London, Her Majesty's Stationery Office. 49 p. Forestry Commission Booklet
41.
Evert, F. Spacing studies - a review. Ottawa, Canada, Canadian Forestry Service.
1971 95 P Forest Management Institute Information Report FMR-X-37*
FAO Project findings and recommendations. Svanna Forestry Research Station,
1976 Nigeria. Rome, FAO. FOiDP/NIR/7 3/007 , Terminal Report. 66 p.
FAO/IOTRO Proceedings of the International Symposium on Forest Fertilization. Paris,
1973 Minist&re de 1' Agriculture. 404 p.
Fryer, J.D and Evans, SA Weed control handbook. Vol. It Principles* Oxford, Blackwell.
1970
Fryer, J.D., and Makepeace, R.J. Weed control handbook. Vol. Hi Recommendations.
1972 Oxford, Blackwell.
-76-
Gentle, 3.W., and Humphreys, F.R. Experience with phosphatio fertilizers in man-surfs
1967 forests of Pinus radiata in New South Wales. In Proceedings of FAO World
Symposium on Man-Made Forests and Their Industrial Importance, Vol. 3 t
pp. 1753-1800. Rome, FAO.
Qessel, S.P. et al. How to fertilize trees and measure response. Washington, B.C.,
1960 National Plant Food Institute. 67 p.
door, C.P. van. Fertilization of conifer plantations. Irish Forestry, 27(2): 68-80.
1970
Griffith, A.L. The best date of planting softwoods at Muguga (Kenya). Empire Forestry
1957 Review, 36(1)1 94-
Haoskaylo, E. (ed. ). Myoorrhizal - proceedings of the First North American Conference on
1971 Myoorrhizal. Washington, B.C., U.S. Government Printing Office. 255 p.
Miscellaneous Publication 1189.
Jackson, J.K* Silviculture and mensuration. Savanna Forestry Research Station, Nigeria.
1974 Rome, FAO. 65 p. FOiSF/NIR 16, Technical Report 1.
Jackson, J.K. Use of fertilizers in savanna plantations, jh Savanna Afforestation in
1977 Africa, pp. 152-159- Rome, FAO. FORiTF-RAF 95 ' v
Kowal, J.M. Report on research proposals for the soil physios and soil chemistry sections
1975 of the Savanna Forestry Research Station. Rome, FAO. FAO: DP/NIR/73/007,
unpublished report.
Kozlowski, T.T. Implications of tree physiology in forestry. _In Proceedings of tree
1973 Physiology Colloguium, pp. 1-25. Madison, U.S.A., University of Wisconsin.
Laurie, M.V. Tree planting practices in African savannas. Rome, FAO. 185 p. FAO Forestry
1974 Development Paper No. 19.
Lejeune, D.R. Development of a mechanical fertiliser dispensing device for planting
1976 machines. Technical Notes. Australian Forestry, 39(l): 57-61.
Low, A.J., and Oakley, J.S. Tubed seedlings. London, Her Majesty's Stationery Office.
1975 Forestry Commission Leaflet 61.
Low, A.J., and Tol, 0. van. Initial spacing in relation to stand establishment. In
1974 Proceedings of IUFRO Symposium on Stand Establishment, pp. 296-319.
Wageningen, The Netherlands.
Maki, T.E. The dependence of forestry and wood production and fertilizers. Paper for
1972 Seventh World Forestry Congress, Buenos Aires. 6 p.
Manktelow, E. Machine planting in Tarawera Forest. New Zealand Journal of Forestry,
1967 12(2)t 183-188.
Marx, B.H. and Bryan, W.C. The significance of myoorrhizae to forest trees. In Forest
1975 soils and forest land management. Bernier, B., and Winget, C.H. pp.
107-117. Quebec, Les Presses de 1'Universit* Laval.
Mikola, P. Afforestation of treeless areass importance and technique of myoorrhizal
1969 inoculation. Unasylva, 23(0, No. 92s 35-48.
-77-
Momoh 9 Z.O. rt al. The role of mycorrhizal in afforestation - the Nigerian experience*
1977 In Savanna afforestation in Afrioa y pp. 100-105* Rome, FAD. PORiTF-RAF
9?
Nao 9 T.V. Fertilisers in forest management. Span, 17(2): 68-72.
1974
Parry, M.S. Tree planting practices in tropical Africa. Rome, FAO. 298 p. FAO Forestry
1956 Development Paper No. 8.
Pritohett, W.L., and Oooding, J.W. Fertilizer recommendations for pines in the Southeastern
1975 Coastal Plain of the United States. Gainesville, U.S.A., University of
Florida. 23 p. Bulletin 774.
Pritohett, W.L., and Smith, W.H. Management of wet savanna forest soils for pine production.
1974 Gainesville, U.S.A., University of Florida. 22 p. Bulletin 762 (Technical).
Rennie, P.J. Forest fertilization in Canada. Paper for Seventh World Forestry Congress,
1972 Buenos Aires. 13 P
Ronoo, F. Planting Ehgelmann spruce. Fort Collins, U.S.A., Rooky Mountain Forest and
1972 Range Experiment Station. 24 p. USD A Forest Service Research Paper RM-89.
Sandvik, M. Biological aspects of planting and direct seeding in forestry. In Proceedings
1974 of IUPRD Symposium on Stand Establishment, pp. 184-201. Wageningen, The
Netherlands.
Sohmidt-Vogt, H. Influence of plant size on survival and growth of young forest plantat-
1967 ions. Iii Proceedings of FAO World Symposium on Nan-Made Forests and Their
Industrial Importance, Vol. 3, pp. 1615-1630. Rome, FAO.
Sohmidt-Vogt, H. Planting material. In Proceedings IUFRO Symposium on Stand Establishment,
1974 pp. 70-90. Wageningen, The Netherlands.
Schubert, O.H., and Adams, R.S. Reforestation practices for conifers in California.
1971 Sacramento, U.S.A., Division of Forestry, State of California, p. 359.
Shoulders, E. , and NoKee, W.H. Jr. Pine nutrition in the West Gulf Coastal Plaint a status
1973 report. New Orleans, U.S.A., Southern Forest Experiment Station. USD A
Forest Service General Technical Report 30-2.
Stone, E.C. Prevention of container-induced root malformation in Pinus pinaster and Pinus
1971 halepensis seedlings following transplanting. (Mimeographed).
Strehlke, B. Ergonomic aspects of planting machines. In Proceedings of IUFRO Symposium on
1974 Stand Establishment, pp. 277-290. Wageningen, The Netherlands.
Swan, H.S.D. The fertilization of man-made forests. In Proceedings of FAO World Symposium
1967 on Han-Made Forests and Their Industrial Importance, Vol. 1, pp. 415-434*
Rome, FAO.
Tinus, R.W. et al. Proceedings of the North American Containerised Forest Tree Seedling
1974 Symposium. Denver, U.S.A. 458 p. Great Plains Agricultural Council
Publication No. 68.
Touaet, Q. Les plantations forestilres en mcttes. Revue Bois et Fortts des Tropiques,
1972 no. 142i 3-13.
-78-
Wakely, F0 Planting the southern pines. Washington, USDA Forest Service. 233 p.
1954
Agriculture Monograph No* 18.
Walker f L.C. Forest Fertilization in North America. Paper for Seventh World Forestry
1972
Congress y Buenos Aires. 3
Waring, H.D. The role of nitrogen in the maintenance of productivity in conifer
1967 plantations. In Proceedings of PAD World Symposium on Man-Made Forests
and Their Industrial Importance, Vol. 2, pp. 1249-1273. Rome, FAO.
Waring, H.D. Barly fertilisation for maximum production. In Proceedings of the FAD/IUPRD
1973 International Symposium on Forest Fertilization, pp. 215-241. Paris,
Ministlre de I 1 Agriculture.
Wilde, S.A. Myoorrhizali their role in tree nutrition and timber production. Madison,
1968 U.S.A., The University of Wisconsin. 30 p. Research Bulletin 272.
Wilde, S.A. et, al. Tree spacing in forest plantations as related to soils and revenue.
1968 Madison, U.S.A., University of Wisconsin. 22 p. Bulletin 589.
Woods, R.V. Early silviculture for upgrading productivity on marginal Pinus radiata
1976 sites in the south-eastern region of South Australia. South Australia,
Government Printer. 90 p. Woods and Forests Department Bulletin 24.
-79-
CHAPTER 4
SPECIAL TECHNIQUES FDR DIFFICULT SITES
Chapters 1 to 3 were concerned with site preparation and planting methods primarily
on firm ground of gentle terrain where soil moisture was neither excessive nor so limiting
as to require irrigation or the construction of special water-retaining structures. This
chapter describes techniques which have been developed for particularly difficult sites i
1) areas where soil and water conservation measures are critical factors for forest
establishment f 2) irrigable sites, 3) sand dunes t 4) waterlogged sites and 5) mine tips and
soil dumps.
SITES WHERE SOIL AND WATER CONSERVATION MEASURES
ARE CRITICAL FACTORS IN FOREST ESTABLISHMENT
This section is concerned with two distinct sets of environmental conditions having
one important factor in common - the need to retard or prevent the runoff of rain water
falling on the ground. The two environmental categories are sites prone to erosion and
arid sites. The need to combine soil and water conservation techniques with tree planting
is a characteristic common to both site types. Soil and water conservation techniques axe
age-old; although in modern times many new techniques have been developed, first using
manpower but recently using mechanized methods to an ever-increasing extent.
Site Conditions and Runoff
Sites Prone to Erosion
These are areas with eroding or erodible soils, generally with moderate to steeply
sloping surfaces, which are from time to time subject to rainfall intensities capable of
producing surface runoff in amounts damaging to the soil structure in the oatohment areas.
Excessive runoff can also lead to downstream damage in the form of si It at ion and destructive
inundations.
Land subject to severe erosion occurs commonly in the hilly or mountainous parts of
those olimatio regions with sharply differentiated dry and rainy seasons but also in areas
with extensive and heavy rainfalls. In areas with a marked dry season, the surface soil
layers tend to become dry and compacted and less able to absorb the rainfall at the onset
-80-
of the rainy season. Even when the soil has beoome recharged to field capacity, occasional
high intensity precipitation during storms can exceed the soil's capacity for infiltration,
percolation and disposal through subsoil drainage, resulting in surface runoff in concen-
trations which cause soil erosion.
A dense ground cover of permanent vegetation is the best form of protection for
soils in such environments. The aerial parts of the vegetation offer physical obstruction
to heavy rain and rapid runoff, while the roots and humus-rich horizons facilitate
infiltration and absorption of the rain water into the soil. The total destruction of this
surface cover for arable cultivation or by persistent burning soon leads to conditions of
severe soil erosion and the depletion of catchment efficiency with the concomitants of
degraded soils, reduced farming yields and floods. The removal of litter and vegetation
for fuel is another factor contributing to soil degradation. In such conditions the rest-
oration of the vegetation cover - usually, but not necessarily always by afforestation -
becomes a sine qua non for the control of erosion and further prevention of site deter-
ioration.
Arid Sites
The arid and sub-desert areas are characterized by a long dry season and annual
rainfall as low as 10 to 200 mm. Such areas are more or less sparsely vegetated with deep
rooting, xerophytio shrubs, bushes and low trees. The rainy season is usually short in
duration, but rainfall, when it oomes, often takes the form of high intensity storms giving
high surface runoff, so that a large volume of the water is lost in flood spates. The
development of techniques capable of holding a large proportion of this runoff in the soil
has made possible afforestation with trees of greater economic interest than the native
xerophytes in certain areas such as North Africa. South of the Sahara in the Sane li an zone,
the establishment of trees at rainfalls of 200 to 500 mm presents tremendous problems except
for a few exceptional, favourable sites.
The Problem of Surface Runoff
The basic aim of soil and water conservation is to create conditions wherein rain-
fall, or water from snow melt, can be held and encouraged to percolate directly in the soil.
In other words, the object is to reduce runoff to a minimum, provided that water for
reservoir storage is not a problem.
In regions of abundant or adequate rainfall, soil moisture may be adequate to support
both a tree crop and a mo:^ or less dense cover of ground vegetation. On such sites,
afforestation requires a minimum disturbance of the existing ground cover sufficient only to
enable the introduced tree crop to grow without harmful competition. In this situation, the
problem is to control runoff and soil wash until such time as the new forest cover can
develop its own capacity for soil protection. The extent and costs of preliminary soil
conservation works can often be reduced if the native ground cover can be intensified by
protection from such destructive factors as cultivation of unsuitable sites, excessive
grazing of domestic livestock or persistent burning. In Cyprus the total exclusion of goat
grazing from burned-over forest areas in the mountain lands resulted in so dense a regrowth
of the indigenous shrubs and maquis vegetation in the course of two or three years, that
the previously applied and costly soil conservation works could be dispensed with almost
entirely.
On arid sites the emphasis is more on the need to collect and retain rain falling
on the plantation site for utilization by the forest trees during the growing season. In
suoh circumstances the competition of existing vegetation for limited soil water reserves
oan prove critical, so that afforestation techniques on arid sites favour olean cultivation
and water retaining structures.
-81-
The objective of all soil conservation and water retention techniques is to induce
or to maintain conditions of maximum water infiltration, absorption and disposal through
subsoil drainage. Each site will have an optimum water absorption, depending on
the vegetative cover, the surface litter and the texture of the soil through all horizons
to the underlying bedrock formations* Conservation techniques should aim to restore the
water retaining capacity of the site to its optimum level. During heavy precipitation,
rainfall intensity often exceeds infiltration capacity and water begins to run off.
Conservation measures should, therefore, be designed to store in reservoir form as much
runoff water as possible and to provide for the safe disposal of any water which is surplus
to the created reservoir capacity. Under certain conditions, particularly on mudstone
slopes or unstable soils, increased water retention is liable to result in landslips, and
on such sites certain water conservation measures oould prove harmful.
The design of conservation measures, their capacity and complexity and, therefore,
their cost will derive from the terrain and from the forecast of rainfall amounts and
intensities as compared with the water retention capacity of the site. Such rainfall
forecasts can be reasonably accurate if long term data (including rainfall intensity
records) are available for the area together with runoff data, as recorded by experimental
runoff plots and local stream flow gauges. In the absence of such data the forester will
have to design the conservation plan on the basis of the best local experience available,
as the time available for investigation and research is often limited.
The less detailed or reliable the information and data are for making estimates of
peak runoff from a given site, the greater the emphasis should be on the inclusion of drains
and other devices for diverting surplus runoff into controlled discharge drains.
Soil and Water Conservation Methods in Regions of Good Rainfall
A great deal of technical experience has been recorded on the subject of erosion
and on soil and water conservation techniques. The intention here is to discuss briefly
those measures which are commonly employed in combination with afforestation.
Re vegetation
In areas where rainfall is sufficiently plentiful or well distributed through the
year to maintain a relatively lush ground cover of indigenous species, the first step to
be taken is to ensure the protection of the site from any form of use reducing the effect-
iveness of this natural vegetative cover*
The most commonly encountered destructive factors are fires, overgrazing, and
shifting cultivation. Protection against such forms of damage nearly always involve
disruption of traditional methods of land use and the introduction of new systems of land
management. Such changes may provoke hostile reactions from the communities affected
unless social problems are identified and analyzed and acceptable solutions found. In the
example from Cyprus mentioned earlier, the land set aside for afforestation consisted of
hilly forest reserves traditionally grazed by livestock owned by fringing communities. The
herdsmen, usually a landless minority community, in return for agreeing to abandon forest
grazing, were compensated by grants of agricultural holdings, sometimes excised from other
parts of the reserve, or by grants in cash sufficient to enable them to set themselves up
in some other form of employment* With the cessation of grazing, the fire hazard was
greatly diminished*
In Cyprus a solution to overgrazing was relatively simple; other countries facing
similar erosion problems are evolving other solutions suitable to their varying conditions.
In Yugoslavia the abolition of forest grazing was greatly assisted by planned industrial
development which was able to absorb the migrating forest grazing communities* In Greece
and Turkey more emphasis is given to the development of improved range lands and the
introduction of high-productivity livestock as indirect compensation for the closure of
other sectors of the catchment destined for afforestation*
-82-
In South Korea the national encouragement of oammunity self relianoe and the
development of village forests is proving an effeotive way of reforesting marginal, eroded
hill lands. In Thailand the setting up of forest villages, together with the provision of
land for cultivation and oash benefits from afforestation work, is reducing shifting
cultivation by offering the cultivators a settled and higher standard of living. In
Indonesia t the provision of oash subsidies and the development of a fodder/forest oash
orop system has persuaded farmers to initiate the reforestation of steep catchment land
whioh they had previously cleared but found unsuitable for long-term cultivation.
The exclusion of grazing and shifting cultivation by legal or administrative action
has rarely proved successful unless accompanied by some acceptable compensatory measures.
Water and Soil Retaining Structures
The underlying principle of such structures is to contain or retard the flow of
rainwater off the ground as it falls, preventing surface runoff water from accumulating
in volumes sufficient to cause damage to the land by scouring.
Terracing
The age-old method was to level the land in a series of steps down the mountainside,
the steps being supported by terraced walls of unmortioed masonry where stones were abundant
on the site; on sites lacking stones the terraces were supported by earth banks or bunds
protected by natural vegetation. Modern techniques, as described recently by Sheng (1977),
are mostly adaptations of these ancient soil conservation works.
Construction of narrow contour terraces is a common site preparation technique
on steep, erodible slopes in northwestern Turkey. (FAO photo)
-83-
Contour Steps and Ditohes
Contour steps (i.e. gradoni or banquettes) consist of a ledge dug out of the hill
slope along the contour, the outer edge of the ledge or step being raised above the inner
edge. The contour ditch differs from the contour step only in having a more pronounced
basin and bank effect when viewed in profile.
Contour steps or ditohes can be designed so that their water storage capacity
matches the expected runoff from the strip of land immediately above them, to the next
contour work above. Alternatively, for any fixed design capacity, the frequency of the
contour steps or ditohes - or the width of the interval between them - can be related to
the expected maximum intensity runoff. Several formulae for calculating the size and
frequency of contour ditohes and steps exist. Saooardy (1950 and 1959) working in Algeria
used the following formula!
H 3
| 260 + 10
o
where H is the vertical interval between contour ditohes or banks, and S is the degree of
slope in percent.
A similar formula used in Sri Lanka, among other countries, is:
H "g (-9)
where H is the longtitudinal distance in metres between contour banks and n is the degree
of slope in percent.
In areas liable to erosion the distances in the table below are given as a guide to
the spacing of contour terraces, steps or ditohes.
Table 1: Distance between contour works according to slope
Slope
Distance 8
in metres
(Percent)
Vertical
Horizontal
3
2.0
67.0
6
2.5
42.0
10
3.0
30.0
15
3.4
23.0
25
4.0
16.0
35
4.5
13.0
50
5.0
10.0
The steeper the slope the greater the vertical distance between lines and the
smaller the horizonal distance. This is computed in proportion to the rainfall catchment
area between lines of contour works.
-84-
Contour ditches and steps are usually constructed by hand, using piokaxes or
grubbing hoes. Lines 10 m to 40 m long and 1 m to 1.5 m wide oan be oonstruoted per man-
day depending on the design and size of the ditoh or strip and on the terrain, vegetation
oover and soil structure. Contour steps of 2.3 m width oan also be constructed mechanically,
even on slopes up to 60j6, using orawler tractors fitted with angledozers. This method is
used extensively in Algeria and in Cyprus, where the contour strips are called "oatastrips".
Subsequent subsoiling along the oatastrip increases the capacity of the soil, and henoe the
effectiveness of the entire operation*
On easy slopes (below 25#) where the soil is often deeper, contour ditches oan be
constructed by a tractor-drawn share plough, turning the soil downhill.
An example of the comparative costs per hectare of afforestation and soil
conservation is provided by data reported from Tunisia where both manual and mechanized
methods are in general use. There the manual construction of 550 - 600 linear metres of
contour steps per hectare required 235 man-days of labour. The same work was done by
machine in one day, at one-third the cost. The full costs in 1966 of plantation establish-
ment are shown in Table 2.
Table 2: Costs of Afforestation Combined with Soil Conservation
Works in Tunisia
In US Dollars (1 Dinar - US$ 1.90) and Man-days (m/d)
Work Item
By Hand
By Machine
With
Banquettes
With
Steps
With
Banquettes
On lees
sloping
land
Clearing vegetation
s 123.98
150 m/d
t 123.98
150 m/d
$ 93.88
126 m/d
S 62.32
80 m/d
Construction of banquettes
(550-600 linear m per ha)
S 177.13
235 m/d
s 57.90
1 m/d
Construction of steps in
broken lines
(800-1000 linear m per ha)
$ 73.44
105 m/d
Sub-soiling
_
$ 41.80
1 m/d
$ 32.30
1 m/d
Construction of access
roads
1 17.95
13 m/d
1 13.63
5 m/d
Cost of planting stock
$ 45.16
22 m/d
Transport and planting
$ 31.16
40 m/d
Tending and replacements
1 45.36
25 m/d
$ 49-16
25 m/d
t 39.33
20 m/d
TOTAL
$ 440.00
485 m/d
$ 337.00
355 m/d
I 332.00
220 m/d
$ 224.00
168 m/d
-as-
To be effective it is essential that the location of the ditches be aligned
accurately using surveyors' levels and that the ditches be subsequently constructed exactly
on the pegged lines. Nonetheless experience has shown that it is difficult to construct
lines of steps or ditches exactly on the contour, however accurately pegged out, with the
result that where errcve have occurred, water accumulating in these slight dips in the line
sooner or later overflows, creating just the sort of damaging runoff which the system seeks
to eliminate. Damage resulting from minor deviations from the contour can be mitigated to
some extent by the construction of sopta across the ditch or step, which in effect divide
the ditch into a series of compartments or basin*, increasing the amount of water retention
on lines having a slight downward inclination.
Inaccurate construction, especially on difficult terrain or where the workers lack
the necessary skills, has been frequently encountered, and this has led to the introduction
of alternative systems incorporating occasional graded ditches between "broken" lines of
contour ditches and steps (i.e. < laments de banquettes).
Varying Grade Contour Ditches
One method of overcoming the danger of accelerated erosion arising from faults in
the levels of contour ditches is to construct at intervals down the slope a series of
graded ditches designed to evacuate runoff water from the hill face to specially constructed
discharge points in the beds of natural drainage channels. The inclination of the drainage
ditches should be 0.5$, increasing in stages of 1.0$ towards the discharge end. The length
of these graded trenches will depend on the topography, but it is advisable to keep the
length as short as possible. The greater the length, the larger and the more oostly must
be the cross-section dimensions. Lengths exceeding 500 metres should be avoided, if possible.
These graded ditches must be pegged out and constructed with considerable accuracy.
Their frequency and location must be decided partly on consideration of the estimated
quantities of runoff water and partly to avoid rooky outcrops or other obstacles lying on
possible courses. The main disadvantage of the graded ditch is the absolute necessity to
maintain the channel in good condition by removing at frequent intervals accumulations of
debris, earth and stones which may be washed into the ditch after heavy storms. If such
maintenance is neglected the channel will become choked and will spill its water at the
point of blockage down the unprotected hillside, possibly overwhelming the whole system of
downhill ditches and thereby adding, sometimes spectacularly, to the erosion problem the
ditches were designed to control.
The maintenance difficulty, experienced in many afforestation projects, where
labour and supervisory staff may have to be concentrated in other areas of the project,
has tended to limit the use of this system to the incorporation of an occasional line of
graded ditches as a kind of safety-valve with other types of conservation works.
Broken Contour Line Techniques
These have evolved from the contour ditch or step method previously described and
include the digging of planting holes or steps on the slopes between the contour lines.
In their simplest form, they would consist of a number of steps 0.6 to 1 m square, hacked
out of the hillside at distances dictated by the plantation spacing prescribed. A few
seeds or a single plant are put in each square.
When the plantation spacing is relatively dense, these square steps are elongated
laterally along the contour to provide short distances of steps or ditches, leaving short
intervening stretches of untouched vegetated land. The row of trenches or steps next
below would be staggered in such a way as to catch runoff water passing through the gaps
in the line above. This method has been extensively applied in Morocco and Algeria where
the broken lines of steps are called ellments de banquette. This method has the advantage
that very accurate levelling can be dispensed with, since it relies on a multiplicity of
small steps or ditches to provide protection against runoff and soil erosion. Even where
-86-
unbroken contour ditches or varying grade ditches are used it is often necessary to prepare
planting holes or short lengths of steps or ditches between the main contour works, in
order to maintain a more or less regular plantation espaoement.
A variation of the broken line system, generally known as the H o re scent method",
consists of digging a small basin from which trenches lead out laterally at a slight
upward inclination, concentrating rainwater runoff in the basin* The tree is usually
planted above the basin. The orescent method is particularly applicable on drier sites
and with relatively wide planting espaoements.
Tied-Ridging Method
This method is an adaptation from an agricultural system of water conservation
practised in East Africa, resembling the North American "basin- listing* method, by which
the entire surface of the land is covered with basin-like farrows scooped out along the
contour with a special plough* In the East African tied-ridge system as applied in
afforestation, the land is first ploughed or hoed and then ridged up in lines 2.5 m apart
roughly along the contour, these ridges are "tied" by secondary ridges constructed at
right-angles to the main ridge lines at intervals of 3 m, forming a series of basins,
which are capable of trapping a sudden 50 mm storm. In compacted soils this method has
proved superior to sub-soiling due to the fact that the whole rainfall is trapped and
utilised. Its application however is limited to flat or gently sloping land.
Wicker Work Fences
On steep slopes where the soil is unstable and liable to creep, the construction
of contour steps and ditches may merely serve to increase instability or even to accentuate
the rate of earth slip. In such situations the implantation along the contour of rough
wicker work fences can help to stabilise the soil temporarily until permanent fixation is
achieved by the roots of planted trees and a cover of invading vegetation. These fences
are constructed by driving a line of wooden pickets of sons durable species into the
ground at about 1 m intervals and weaving between the pickets a mass of branohwood. The
height of the wicker fences above ground level varies between 0.3 and 1 m. In Japan
unstable slopes are sometimes mulched with rice straw pegged into the ground to completely
cover the strips between the wicker fence lines.
On unstable soils or stony screes, wicker work fences are often useful, but these
sites are generally too impoverished to plant without further treatment. It may be
necessary therefore to import good loam or forest soil from elsewhere to fill in the
planting holes to give th young trees a good start, but this, of course, is a costly
operation. A cover of wire netting can also be used to hold and stabilise scree slopes*
Ravine and Torrent Control Methods
On sites where erosion has reached an advanced stage, it is common to find the
land deeply dissected by ravines and gullies excavated by runoff water from the slopes.
Unless stabilised by vegetation or by the mechanical action of check dams, such ravines
gradually become deeper through the scouring action of the water flows, which also under-
mine the banks causing their collapse and a gradual lateral extension of the ravine.
Actively eroding ravines should be stabilised at the same time as the hill slopes,
otherwise they can eventually destroy the effectiveness of conservation measures
constructed on the planting sites. Heede (1977) has described the construction of gully
control works*
Wherever contour steps or ditches cress ravines, the banks of the ditches will
require strengthening by stone revetments; but in the oase of ravines exceeding one
square metre in cross-section, it is advisable to stop the contour works some metres
from the edge of the ravine to guard against the possibility of the ravine banks eroding
outwards and "tapping" the contour work.
-87-
Where graded ditches discharge into a ravine it is essential to avoid cascading the
water into the ravine f since this will result in the ditoh channel being eroded back. Where
stones are available a masonry check dam should be constructed across the ravine to a height
level with the bank of the contour ditoh and more or less continuous with it. The water
from the ditoh can thus flow into the ravine behind the check dam without cascading. The
wall of the check dam should be provided with an outlet spillway at the top and a masonry
apron at the bottom to prevent water undermining the foundations of the dam wall.
When building check dams the following points should be noted!
1) The foundations should be strongly made and bedded into rook;
2) The ends should be revetted well into the banks of the ravine to
prevent water seeping round the wall, eventually causing a
collapse;
3) The downstream face of the wall should be given a pronounced
back-slope (1:2 inclination from the vertical if uncut stones or
boulders are used; 1:3 for dry-masonry walls of roughly out
stones; 1:4 to 1:6 if cement masonry or oast cement walls are
used). The upstream face of the wall can be vertical but it
should be filled up with rock and debris to the level of the
spillway;
4) A spillway must be incorporated in the top centre of the dam
wall f sufficiently large to pass the maximum torrent flows
expected. The spillway should be constructed of large flat stones,
preferably cemented together in the top course of masonry.
To ensure thorough stabilization of the ravine, a series of check dams should be
constructed from top to bottom? the dams being so spaced that they complement each other's
effects. This rule can be relaxed to allow a slope of not more than 5 percent to build up
in the torrent bed between each pair of check dams.
Check dams may be constructed of 1) logs and fascines set across the ravine and
held in place by posts driven well into the soil, 2) of masonry (where suitable stones are
available), 3) of gabions (galvanized steel wire netting "baskets' 1 or "sausages 11 filled
with stones and pebbles), or 4) of reinforced concrete. Brushwood check dams are useful
in small gullies, particularly if the brush includes a species capable of vegetative
reproduction and if the upstream side of the dam is well sodded* The choice of material
used for check dams depends on the following factors:
1) The slope of the ravine bed and its cross-section dimensions, hence
the volume and velocity of the torrent flows to be controlled;
2) The type of construction material most convenient to the site, and
3) The value of the land, including lines of communications, habit-
ations etc., situated below the ravine and which the stabilization
works are required to protect. Under some circumstances the cost
of ravine stabilization may exceed the value of the protection
gained, in which case some compromise needs to be struck in the
planning stage* This compromise may take the form of confining
stabilization work to the smaller branch ravines, and reducing the
number of the larger and more oortly structures in the main ravines.
-88-
Water Conservation Measures on Arid Sites
Successful afforestation in very low rainfall areas (down to 200 mm) depends on
securing maximum absorption and retention of sporadic rainfall by the soil in the areas
to be oooupied by roots of the trees* The spacing between trees will generally increase
with decreasing rainfall* Land between tree rows which is not expected to be occupied by
tree roots in the future can be regarded as water catchment areas for the planted zone.
It follows that any indigenous vegetation should be eliminated so as to minimize
competition for soil moisture, except on sites where such denudation could lead to wind
erosion of the exposed topsoil.
Contour Banks
One method of site preparation designed to meet the basic requirement of maximum
water storage for afforestation on arid sites consists of forming a series of large banks
or bunds sited accurately on the contour and constructed of earth and stones scraped off
the catchment zones above each line of banks* The forest trees are planted either on y
just below or just above the banks*
In most cases, and especially where the soil is compacted or a hardpan occurs near
the surface, deep sub soil ing or ripping should be carried out prior to the construction of
the bank. The subsoiled band should be broad enough to extend on either side of the bank
to loosen the soil throughout the tree root zone. The existing vegetation should be
eliminated by grubbing, hoeing or disc-harrowing and should be spread as a mulch roiu
the trees after planting.
The height of the contour banks is determined by the estimated quantity of runoff
to be contained after each heavy rainfall. Where there is a possibility of high intensity
rainfall, the banks should be provided with devices for spilling surplus water into
prepared channels or drainage ways. These safety-valve spillways should be strongly
constructed to resist the scouring of breaches in the banks and should be large enough to
allow an ample safety margin to cope with storm runoff flows.
The construction of such extensive earthworks is too arduous and too costly to be
carried out except by heavy earthmoving machinery.
Under arid conditions tree planting in simple holes without water conservation
measures rarely succeeds, unless facilities exist for watering or irrigating the trees
throughout the dry seasons until the plantations have become fully established.
Methods Steppique
In recent years the increasing availability of specialized agricultural and heavy
machinery has enabled foresters in arid and sub-desert zones to attempt afforestation
projects in areas formerly considered technically un pi ant able. Some of the most
spectacularly successful arid zone afforestation has been accomplished in Morocco and
Algeria, where techniques have been developed under the name nrfthode steppique.
Under the most favourable site conditions in these countries (i.e. on relatively
deep, level or gently sloping soils with annual rainfall of 300 - 500 mm spread over five
winter months), site preparation is confined to deep sub soiling with a heavy rooter fitted
with 2 or 3 tines penetrating to depths of 60 - 80 cm. The area is subsoiled in continuous
lines in one direction, and sometimes by passing the machine in criss-cross lines. The
subsoiling loosens the soil to such an extent that all rain water is absorbed. Trees are
then planted at spaoings of at least 3 * 3 cr 4 x 4 m. Under certain conditions, subsoiling
may be dispensed with altogether, it being sufficient to cultivate the land with agricult-
ural implements to break up the soil surface and to destroy existing vegetation. Most of
the extensive Eucalyptus plantations in the Marmora region of Morocco were established in
this way.
-89-
More commonly, subsoiling is accompanied by the construction of banks or ridges 0.5
to 1.0 m in height with bases 2.0 - 3.0 m wide. These banks are pushed up by heavy crawler
tractors (150 - 230 hp) carrying bulldozers or angledozer blades. The smaller 0.5 m banks
are made by traversing on the contour with an angledozer, returning on the same line with
the blade angle reversed. The larger banks are made by bulldozing soil from the land lying
above the line of bank in a series of backward and forward movements. The strips between
the banks may be further subsoiled if necessary. On gentle slopes, the banks are often
made in broken, staggered rows, forcing surface runoff downhill in a zig zag direction
through the staggered gaps, effectively spreading the water for improved absorption by the
soil.
Although in some areas, for example Cuba (Masson ? 1973) t subsoiling is done on slopes
up to 40$, the practice is generally confined to slopes of less than 25$. The method used
for steep slopes is the construction of narrow terraces out into the hills by angledozers
(e.g. the M oatastrip u method used in Cyprus described on page 84). A subsoiler can be
subsequently passed along the bed of the terrace onoe the angledozer has completed forming
the terrace.
Trees are normally planted partway down the slope of the banks corresponding to the
original soil level. The mass of loose soil forming the bank favours easy penetration by
the tree roots, and experience has demonstrated that trees planted on the banks grow
considerably better than those planted on land which has only been subsoiled.
In areas subject to strong desiccating winds it has been found expedient to plough
deep furrows (in Algeria the single share mould-board plough is preferred) and to plant
the trees in the bottom of the furrow. This provides good shelter from the wind during the
first one or two seasons. A combination of banking and deep furrowing provides even better
protection from the wind.
Emphasis must be laid on the necessity for removing all vegetation from the
plantation area and for keeping the surface clean weeded for two or three years after
planting until the trees are well established. The xerophytio vegetation is usually
deeprooting and has a strong and persistent capacity for re-sprouting. It is, therefore,
essential to uproot this vegetation as far as possible by disc-ploughing or harrowing or
by hand grubbing where the vegetation contains a high proportion of woody species. Hand
grubbing is laborious and expensive; mechanized clearing is easier, and for this,
specially adapted subsoilers (rasettes) are available which are fitted with a forward
projecting cutting blade spanning the points of the subsoiler's tines. As the tractor
progresses, this blade passes horizontally under the ground and severs the roots, turning
up the stumps in the wake of the subsoiler. The root plough attachment for crawler
tractors has a similar function but with the primary purpose of cutting root systems.
The main site preparation in eastern Morocco is subsoiling, using very heavy
tractors (230 hp) pulling 7-10 ton rooters capable of breaking up crusts and hardpane
to depths of 70 and 80 cm. The construction of banks is usually omitted, except on the
limited areas of deep soil free from hardpan where a large plough capable of opening 50
cm deep furrows is used to throw up contour ridgee on which the trees are subsequently
planted. Over most of the zone, the large plates of rooky crust turned up by the rooters
are such as to make mechanical cultivation of the surface impracticable. The trees are
planted in basins made by hand at the intersection of the subsoiled lines. Special care
is taken to keep all plantations clean-weeded for two years, either by wheeled tractors
with diso-harrows where ground conditions permit, or otherwise by hand. These plantation
methods have enabled Pinus halepensis plantations to survive a year of extreme drought
when no more than 64 mm rainfall was recorded.
-90-
IRRIGATED OR IRRIQABLE SITES
Qeneral Considerations
Irrigated tree planting is generally associated with arid sites where the annual
rainfall rarely exceeds 200 nun or with semi-arid sites, where the rainy period is short ,
both resulting in long periods when soil moisture is deficient* Under such conditions,
indigenous forest growth is either absent or limited to xerophytio species with very deep
taproots and strongly developed transpiration control mechanisms. Such areas have an
extremely low productivity and are usually of limited economic interest.
Some desert or sub-desert lands, however, have proved suitable for the production
of economic forestry crops using irrigation. Notable developments of irrigated tree
plantations exist in the Sind Desert of Pakistan, in Iraq, in Egypt and in central Sudan.
Apart from the desert or semi-desert regions, irrigation has also been associated
with the culture of poplars, and to a lesser extent of willows, in regions characterized
by a relatively high winter or seasonal rainfall alternating with a pronounced dry summer
season, such as in the higher altitude districts of the Mediterranean and in countries
with continental climates. Under these climatic conditions, the soil moisture regime is
normally not a limiting factor to tree growth, except for such fast-growing species as
poplars, which require moist soil throughout the year.
Growing forest trees under irrigation has developed from row and ornamental
plantations in agricultural areas, and most forest irrigation methods have adapted methods
used for the field crops grown in the same locality. However, in recent years forest
research has questioned the advisability of following these agricultural methods too
closely. Some of the questions to be answered by research into irrigated silviculture ares
1) The optimal yearly consumptive use of water (i.e. crop water
requirement) for each species, that is, the quantities and timing
of water needs. The water requirement varies with climate and
species and even for different provenances within a species;
2) The best methods of applying the water to the land, giving due
consideration to such factors as conveyance loss, deep percolation
as well a43 future weeding and thinning, and the exploitation of the
crop;
3) The response of indigenous and exotic tree species when grown under
irrigated conditions.
Plantations in Irrigated Agricultural Projects
IXie to the high cost of initial establishment, irrigated plantations will only be
supported in a few regions where there is a serious lack of wood or where other consider-
ations, eruoh as prevention of erosion or desertification have to be taken into account.
Most often, irrigated forests will only be considered as a by-product of an already
existing scheme, and under such conditions the extra cost of irrigated wood production
can be kept within an acceptable range. However, where forest plantations are established
in irrigated agricultural projects, the irrigation layout will normally have been designed
to suit the rhythm of field crop cultivation. The forester is thus obliged to adapt his
methods to this rhythm, which may not be ideal for growing trees. Many irrigated
agricultural systems are also based on a certain crop intensity; however, forest
plantations may need water more or less continuously through the year, therefore the areas
suitable for irrigated forestry are best located on sites accessible to the main arterial
canals which carry water throughout the year.
-91-
Some times irrigation water IB out off for considerable periods of the year
depending on the seasonal flows of source rivers, the storage capacity of reservoirs or on
water usage rights operating downstream* In Pakistan some irrigation sohenes in the Indus
Plain provide water for only six months of the year; for the rest of the year orops depend
on residual soil moisture. Treaty arrangements between Egypt and the Sudan limit the water
withdrawal from the Nile River during certain periods of the year in the Sudan* In the
Qezira irrigation project and others dependent on the Nile water, no irrigation water is
available at all for three and one-half months (mid-March through June) during the hottest f
time of the year, which means that only tree speoies capable of adapting to this inter-
vening drought period can be used.
Most of the older irrigation projects were designed for agriculture without thought
of forest crop product ion. As a result , forest planting was often relegated to sites
un suited for field orops or adjacent to the tail end of irrigation canals. On such sites
water supplies are often irregular, sometimes in excess - leading to waterlogging - and at
other times deficient when the water needs of field orops take priority.
In some more recent irrigation projects, the need for amenity planting, lumber,
and. more particularly, fuel wood for the project communities has been recognized.
Irrigated Afforestation Projects
Although most irrigated afforestation work is assooated with existing agricultural
schemes, sometimes an irrigation system is created solely for production of forest
plantations. In northern Iraq, for example y a number of plantations have been established
in "Ahrash" scrub lands forming broad strips along the banks of the river Tigris and its
tributaries; these are irrigated by water pumped from the river. Similar plantations
exist in the "Oerf" areas flanking parts of the Nile in the Sudan.
In this type of project the forester is responsible for the layout, construction
and operation of the whole irrigation system and though this involves engineering skills
outside his normal training, it has the great advantage that he is ablet generally with
some expert assistance, to design a system to suit the special needs of the tree orops.
The Influence of Soils
Two soil characteristics govern the ohoioe of an irrigation method and also the
quantity of water applied and the frequency of irrigation. These are the rates at whioh
water will enter the soil (infiltration rate) and the capacity of the soil to hold water
for use by the crop (waterholding capacity). Sandy or gravelly soils are most easily
penetrated but hold rauoh less water than a medium or heavy textured soil*
The presence of a water table can also provide a reservoir of soil water for the
tree roots, and once they reach this depth they can grow without or with much less
irrigation t provided salinity is not a problem. For example, in the Khartoum greenbelt
afforestation project, the heavy clay soils restrict water percolation through the surface
layers so that an intervening dry layer between the groundwater table and the wetter
surface zone prevents tree roots reaching the water table.
Salts are always present in the soil and in irrigation water. If these salts are
allowed to accumulate in the upper soil they oan damage and prevent the growth of orops.
During irrigation, additional water is necessary to ensure that these are leached below
the crop root zone. The danger of such salinity is also acute where drainage problems
occur. Wherever the soil is saline it may be necessary to plant only those tree speoies
known to be tolerant of soil salinity; it may also be necessary to equip the project area
with a complementary system of drains capable of drawing off the salts dissolved in
irrigation water. Where saline soils exist, it is advisable to leach these out prior to
planting. In certain oases it may be possible to grow a field crop such as barley, during
the leaching period which oan help to offset the costs involved*
-92-
The foregoing underlines that a thorough a oil survey is an essential prerequisite
for designing the irrigation layout and for selecting the species to be planted*
Irrigation Methods
Of all irrigation systems, surface irrigation is the cheapest and the one best
adapted to tree orops. It can be practised by using either the basin , furrow or border
.methods, of whioh the first two are most commonly used for plantations. In the flood or
basin system, the water is spread evenly over the surface of the ground; in the furrow
system the ground is wetted by lateral infiltration.
Flood Basin and Border Irrigation
The basin method is most suitable on gently sloping land with a more or less even
surface. It consists of a series of medium-size basins with 20 to 30 m sides surrounded
by earth bunds. The basins are filled up one after the other with 10 to 20 om of water
depending on the soil's water-holding capacity.
The border system of irrigation is similar to the basin method but is designed for
smooth sloping surfaces. Rectangular plots 15 - 30 m wide and 100 - 150 m long are
constructed in the direction of the main slope. The plots are separated by earth bunds
20 om high. Ditches run along the upper edge of each plot, and the water flows down the
whole surface into the drainage ditch at the bottom.
Another variant of basin irrigation is very frequently used for poplar cultivation
in mountain valleys, where the land is levelled in a series of terraces following the
contour line. The water enters at the top of the series and each basin is successively
irrigated from spillways constructed in the bunds of the terrace above.
Furrow Irrigation
*
In this system furrows are constructed leading off from the feeder channel in
parallel lines spaced at sufficient intervals to wet the tree rooting zone. The spacing
between furrows and their capacity therefore depends on the permeability of the soil.
Poplars respond well to
irrigation. Those shown
here on the Rhab Plain,
Morocco, are four years
old. (PAO photo)
-93-
As a general rale the heavier the soil the larger and the wider apart the farrows will be;
the opposite applies in more porous soils. In the heavy olay soils of the Khartoum
greenbelt plantations, the farrows are normally spaced at 2.5 m intervals, bat following
recent investigations it has been found that adequate wetting of the root zone can be
obtained by furrows 6 m apart*
This system has special application in elevated areas within irrigation projects
too high to be reached by the normal gravity flow irrigation. Provided the ground is not
more than about 1 m above water level, deep and wide furrows are made, and the trees are
planted on the sides or banks of these farrows* This method is used in Iraq, especially
for plantations of pomegranates and other fruit trees, as well as for plantations of
Eucalyptus and Casuarina. However, the digging of such deep furrows by hand is costly.
Another major disadvantage of this method in forest plantations lies in the obstruction
the furrows offer to the passage of tractors and implements, for example, during inter-
row weeding operations. Such a sub-irrigation system can also cause severe waterlogging
and salinity problems.
Trickle or Drip Irrigation
Trickle or drip irrigation is a modern, complex, precise method of irrigation which
is being developed for agriculture and horticulture but has recently been adapted for the
establishment of tree crops in areas where there are adequate financial resources to meet
the high costs. The main benefits of this method are that it reduces water loss, produces
good crop responses, optimizes fertilizer use and results in less weed growth. In
experiments in Pakistan, drip irrigation used only 22 percent as much water as farrow
irrigation and 15 percent as much as flood irrigation. The main limitations are the high
costs compared with furrow irrigation? the high level of skill required for design,
installation and operation; moisture distribution problems including the sensitivity of
equipment to clogging, and salinity hazards (PAD, 1973)
Trickle or drip irrigation is a watering system where water is distributed to
points without atomization and without soaking the land. The density of the watering
points can be arranged to allow the selected subsoil to be suitably moistened, while the
greater part of the surface soil remains dry. Water delivery is by polyethylene or other
forms of plastic pipes fitted with "drippers" or "tricklers" which deliver a suitable flow
at low pressure, normally within the range of one to two atmospheres. The pipe system is
often buried in the soil to apply moisture at prescribed rooting depths, but under certain
conditions it may be on the surface, allowing easy removal when necessary. Clogging of
drippers is a common problem, and there are a number of approaches and types of drippers
to reduce this difficulty.
Mater requiranemts of tree crops
^ater requirement is the depth of water needed to replenish the available moisture in the
root zone, depleted by evapotranspiration. The water required to enable a forest plantation
to grow at optimum rate will vary from season to season; it will increase with each succeeding
year of the rotation until full crown cover has been attained. If the groundwater table is close
to the surface, requirements will diminish once the roots have reached the ground water.
Like agricultural crops, different tree species have different water requirements, depending
largely on their transpiration control mechanisms.
Crop water requirement, whether of agricultural of forest crops, can be computed using
the following formula:
flT crop Kc. ETo
where ET crop is the crop water requirement in mm over a given period of time (i.e. the
evapotranspiration when soil water supply is non-restricting); To is the reference eva-
potranspiration in mm over the same period; and Kc is the crop coefficient. For a fuller
description of the method see FAO 1977a*
-94-
Reference evapotranspiration -(gPo). is defined as "the rate of evapotranspiration from an
extensive short green cover completely shading the ground and adequately supplied with
water". Empirical formulae have been devised for calculating li/To. Common methods are (i)
the Blaney-Criddle method which is used when only temperature data are available; (ii)
the radiation method which is used when available climatic data include measured air tem-
perature and sunshine, cloudiness or radiation; (iii) the Penman menthod which is used
when measured data on temperature, humidity, wind^and sunshine or radiation are available.
coefficient (Kc). Crop water requirement is affected by several factors including
crop characteristics, stage of growth, and the prevailing weather conditions. Values of
Kc have been established for vegetable and fruit tree crops. Using the Kc values for fruit
trees as a guide, a rough estimate of the coefficient for low-transpiring trees would be
about 0.5; high-transpiring trees would have a coefficient around 0.9 or more. For example,
in subtropical climates with winter rainfall, Lto is about 1,000 - 1,300 mm/year, and the
crop coefficient for low-transpiring fruit trees such as citrus reaches a maximum point
in June-July of around 0.7; ET crop would then be approximately 700 - 900 mm/year. Olive
trees, which are well known for their very low transpiration, would have an estimated crop
coefficient of 0.4 - 0.5 f and the ET crop would consequently be somewhere between 400 and
440 mm/year. High-transpiring tree species may have considerably higher Kc values. The
water requirements for optimum growth of forest crops have been inadequately studied.
Irrigation requirements of tree crops
The main purpose of irrigation is to prevent lack of water from limiting tree growth.
The net irrigation water requirement of a tree crop can be computed by the following
formula:
In ET crop - (Pe + Ge + Wb)
(losses) (gains)
where In = net irrigation requirement (mm/period of time)
ET crop crop water requirement ( ff " "
Pe effective rainfall ( fl !f "
Ge m groundwater contribution ( ft " "
Wb stored soil water at the beginning of each period.
Effective rainfall (Pe). Not all rainfall is effective as part of the water is lost by
surface run-off, by deep percolation, and by direct evaporation. That part of the rain
which penetrates the soil and is effectively available to the trees is defined as the
effective rainfall. Effectiveness of rainfall depends on its intensity, amount and fre-
quency.
Qroundwater contribution (Ge), Groundwater can contribute to the supply of water to trees
when it is within reach of the roots. It is therefore useful to determine the depth of the
watertable in relation to expected tree rooting depth. Watertable depth often varies season-
ally, and seasonal measurements are therefore required. When the groundwater table is close
to the surface, e.g. in valleys, mature trees generally do not require irrigation; in such
cases irrigation may only be needed for the establishment of young plantations, and can
cease when the roots of the trees reach the watertable.
Stored soil water (Wb). The storage capacity of the soil is the quantity of water
available; it ranges between field capacity (soil water tension 0.2 aim.) and wilting
point (15 atm. ). The quantity of water that can be stored depends on the soil texture;
heavy soils store some 200 mm/m f medium textured soils some 140 mm/m f and light textured
soils some 60 mm/m or less. It will be noted that use of the above formula will, theo-
retically, cause Wb to be zero for all successive irrigation periods except the first.
In irrigation, the rate of soil water uptake by the trees and the storage capacity of
the soil play a very important role in determining the depth and frequency of applications.
Heavy soils may receive large applications at extended intervals, whereas light soils re-
quire smaller applications at more frequent intervals.
Relatively little research on net irrigation requirements has been carried out for
forest plantations. In Pakistan, experiments have shown that the optimum amount of water
for Dalbergia sissoo (the most important plantation species) lies between 900 and 1,350 mm,
applied at fortnightly intervals through the six-month irrigation period. The non-availa-
bility of irrigation water during the other six dry winter months limits the selection of
species to those which have an extended period of dormancy.
In the Sudan, investigations on net irrigation requirements in Eucalyptus microtheca
plantations in the black cotton soils of the Gezira indicate that 2,400 mm per year,
applied in 13 irrigations, give good results. The irrigations are made at fortnightly
intervals during the period July to December when irrigation water supply is unrestricted,
and at 6 week intervals from January to March when water is in short supply. From mid-
March to June no irrigation water is available under the Sudan-Egypt agreement. The rain-
fall, which is 230 - 450 mm per year, falls mostly in the summer months from July to Sept-
ember. Investigations carried out in the Khartoum greenbelt indicate that best growth
results when annual irrigation is about 750 mm/ha/year, although mean annual rainfall is
less than 200 mm. Higher irrigation rates lead to waterlogging in the heavy alkaline clays
in this area, and to reduced growth.
In Turkey, scientists working at the National Poplar Institute calculated the water
requirements for poplar plantations at a large number of stations located in the different
climatic regions of the country; the calculations took into account precipitation, normal
shade temperatures, humidity, Gaussen's Coefficient, and calculated global radiation.
Irrigation is normally necessary between May and September, increasing gradually up to July
and August (the hottest and driest months), and thereafter decreasing. The highest water
requirements of about 1,000 to 1,100 mm, for the six-months irrigation season, occur in the
Etiyarbekir region in southeastern Turkey. No irrigation is needed at Rize (in the north-
east Black Sea coastal region) where well distributed annual precipitation averages 2,440
mm and exceeds the calculated maximum evapotranspiration. For most poplar plantations in
Turkey net irrigation water requirement is between 500 and 700 mm.
-96-
The above figures refer to net irrigation requirements. Gross irrigation requirements
may need to take account of leaching requirements (additional water required to flow through
and beyond the root zone in order to prevent salinity build-up) and of the efficiency of
the delivery system.
Response to limited water avA l
Very little is known of the comparative response of different tree species to limited
availability of soil water. Most studies have been related to "optimum" levels of irri-
gation to produce "optimum" growth rate. In many dry areas it may be necessary to limit
water availability at certain seasons to less than the "optimum". More research is needed
on the response of different species to depletion of soil water, expressed as a reduction
in the rates of transpiration and of growth.
Planning the Layout of Irrigated Plantations
As already noted, forestry is usually ancillary to agriculture in irrigation
so he roes, and the setting up of irrigation purely for plantations is an infrequent
occurrence. Planning and designing the layout of an irrigation project is a highly
skilled, precise and demanding task, and it is necessary to call upon high expertise and
specialist advice if an adequate and successful project is to be prepared.
Following is an outline of some of the factors influencing the layout and extent
of irrigated plantations:
1) Gross area commanded by the main canal. This is composed of
(a) the gross irrigable area, where irrigation can be developed
and (b) the non-irrigable area, all land which is unsuitable for
irrigation. The gross irrigable area is composed of the net
irrigable area and the area needed for the roads, water channels
and buildings.
2) Availability and seasonal variation of water supply in relation
to the estimated water requirement of the species selected.
3) Quality of the irrigation water, particularly as regards the
quantities of salts or other toxic elements.
4) Topography. The most suitable sites are on level or gently
sloping lan\ Steeper slopes or land with many undulations and
surface irregularities add to the complexity of the water
distribution system and the oost of levelling work. A detailed
topographical survey with 1 metre contour lines is an essential
preliminary to planning the layout of the whole project.
5) Soils, with particular reference to their permeability, chemical
status and ground water formation.
The main layout plan should delineate on the topographical map 1) the course of
the main canal from its head, or water intake point, to the highest point commanding the
lands to be irrigated, 2) the direction of the main branch canals within the boundaries
of the total area commanded and 3) the location and extent of enclaves of land unsuitable
for irrigation or planting. A detailed soil survey map should be imposed on the topo-
graphical nap. Finally, the layout of future plantation compartments and irrigation
blocks should be determined so that the delivery capacity of the branch canals serving
each irrigation block can be correlated with the areas watered, the periodicity of
irrigation and the water need of the species planted*
-97-
Preparation of the Land and Construction of -the Canal System
After clearing of existing vegetation, the whole area should be roughly levelled.
The objeot of land levelling is to reaoh a good uniformity in water application by an even
flow of water over the soil surface* However, as tree crops seldom support the extra cost
required for full land levelling, it is recommended that lands be chosen with a slope as
even as possible and that levelling be limited to a simple operation of smoothing out only
the main irregularities.
The next operation is to mark out and construct the main distributor channels and
the road network. Bulldozers and graders, if available, are suitable for levelling and
for pushing up embankments. Channels oan be opened by double mould-board drain ploughs or
by excavators, depending on the size of the channel required. Finally, the network of
smaller channels feeding each compartment or plot much be constructed.
Before planting, it is essential to carry out trial or test irrigations to expose
any faults or low plaoes in canal and channel networks and also any areas within the
compartments in need of further levelling.
Flow Capacities in Irrigation Channels
The rate of delivery of water in a channel is a function of its cross-section
dimension, its grade and the smoothness of the surface of the channel bed and sides. The
flow is usually expressed in "cumecs" (cubic metres per second) or "cuBecs" (cubic feet
per seoond)(l ft3 0.0283 n^). There are various forms of gauges which oan be installed
in the channels to measure delivery rates, but in the absence of these a method of
estimating is to multiply the cross-section area of the channel up to the wetted perimeter
(the part of a channel which is wetted by the flow of water) by the flow velocity
(obtained by stop-watch timing of a floating oork over a measured distance of channel).
This will give the volume of water passing a given point per second. This nominal figure
must then be diminished by multiplying by a coefficient representing the drag on the flow
exerted by the roughness of the side of the channel. This coefficient will depend on the
smoothness of the walls and of the dimensions and gradient of the channel. As a rough
guide the coefficient for a channel with a gradient of 1 to 5 000 would be about t
Concrete lined channels 0.80
Clean earth channels 0.70
Channel walls, grassed-over 0.60
Channels obstructed by fairly 0.50
dense vegetation
In the case of unlined channels the coefficient also includes allowance for losses by
seepage.
Sluice Gates, Off-take Regulators and Syphons
All distribution channels require sluice gates or off-take regulators constructed
at all points where subsidiary channels branch off. These are preferably constructed in
concrete or masonry but are sometimes made of wood. The simplest construction consists
of a sliding gate which can be raised or lowered to control the volume of water entering
the subsidiary channel.
Concrete syphons are used at road crossings whenever irrigation channels are at the
same or at higher elevations than the roadway.
-98-
Pumped Irrigation
Situations ooour when land destined for irrigated plantations lies above the level
of the water source. The water must then be raised by pumps to the level of the main
irrigation oanal.
Irrigation pumping usually requires large flows under low heads. The pumps best
suited for this kind of use are of the propeller or mixed-flow type. They oan lift from
1 m3/s to 10 m3/s or more under heads of 3 to 10 ra or more if several stages are used.
Several pumps, preferably of similar design, should be used to provide the total flow
needed for the irrigated area y and if these operate on a 24 h per day basis, an extra
pump should be on hand in oase of breakdowns. These pumps usually have a very good overall
effioienoy. Their rotation speed is low and they are able to operate for long continuous
periods of time without damage. Their wear is very low and they consequently have a long
lifetime of up to 20 years. The propeller or mixed flow pumps are large and must be
installed in sturdy pumping plants especially constructed and adapted to the type of pump
used. In the upper part of the plants the engines are located on a very strong floor
to support their weight. Underneath comes an intermediate level composed of various
vertical casings through which the water flows up and out of the station. The lower part
is where the large pumps are installed. The individual impellers must be at a sufficient
depth below the minimum water level to protect the pumps from the formation of vortex and
from oavitation effects on the blades. Intake grids should be installed in front of the
pumping plants to keep any large floating matter from entering and damaging the pumps.
Likewise there must be gates to isolate each pump for maintenance or repair purposes.
Much smaller pumps oan be used for very small irrigated areas. They oan be either
of the vertical or horizontal type, but in the latter oase the intake pipe should be as
short and as close to the water as possible. Check valves should be installed at their
foot to reduce any problem of suction.
Road Networks
The road network must be planned and constructed simultaneously with the irrigation
channel system, so that the number of bridges, culverts and syphons are kept to a minimum.
All main canals and distributaries should be provided with roads to allow access for oanal
maintenance operations, and no roadside avenue trees should be planted which might
subsequently impede the passage of oanal clearing machines, a precaution that is frequently
overlooked.
Establishment Costs of Irrigated Plantations
Establishing an irrigation scheme is always very costly. At 1966 costs simple surface
irrigation would require an initial investment of at least USt 1 500 per hectare. The major
expense item is the cost of oonstruoting the oanal and road network, especially if the whole
cost of the canal system is included in the forest budget. In existing irrigation schemes
for agricultural development f the capital charge for the construction of the main oanal and
distribution network is born entirely by the irrigation authority, which may or may not
charge a rate on the water supplied to the forest authority. In the Indus Desert in
Pakistan, forest plantations paid an irrigation water rate per hectare; but in the Sudan,
irrigation water in the Qezira and greenbelt plantations, is provided without charge to the
foreert authority, which is therefore concerned only with the layout of secondary feeder
channels within the plantation*
-99-
3AND DUNE SITES
General Considerations
Vast areas of unstable sand dunes ooour throughout the world in all olimatio
regions wherever regular strong winds and friable topsoils ooour. Some areas of sand-
drift originate along shore lines with wide strips of sandy beaches, and at times of
strong winds the sand is blown inland to form what are called mar i time dunes, as distinct
from continental dune formations, which have no relation to the sea and usually result
from the destruction of the native vegetation by cultivation or overgrassing. Noteworthy
examples of continental dunes ooour in the "dust-bowl areas' 1 of central U.S.A. and in the
semi-arid sandy steppe lands of the lower basins of the Don and Volga rivers in U.S.S.R.
When wind erosion occurs, the coarser particles of sand or soil are carried close
to the ground surface, about 90$ of the material within 30 cm and some 57$ within 5 cm of
the surface. These particles move in a series of bumping movements and induce movement
in other particles in a type of saltation process. Sand dunes or hillocks form as the
blowing sand encounters bushes, trees or some obstruction capable of creating turbulence.
This turbulence reduces the carrying force of the wind to both the windward and leeward
sides of the obstacle, causing the sand to be deposited in mounds until the obstacle has
been completely engulfed in the dune. Dunes extend in the direction of the wind as sand
is blown up the windward face of a dune over the crest and again deposited by turbulence
on the leeward side. Rates of advance of as much as one metre a month during periods of
very high winds have been observed.
Drifting sand can become a menace by encroaching on agricultural land or by
blocking canals and lines of communication, or even by engulfing habitations. If, however,
the drift sands can be stabilized, experience shows that they can often be successfully
afforested and can, under favourable climatic conditions, become very productive. The
Pinus pinaster forests in southwest Prance in Les Landes offer a good example of successful
reclamation of a former waste of dunes formed by strong prevailing winds blowing in off the
Atlantic in the Bay of Biscay. There are many other examples of successfully stabilized
dune formations, e.g. those in North Jutland in Denmark, in Tunisia and in western Libya
where the fixation and afforestation of vast areas of both maritime and continental dunes
are among the principal tasks of the forest services.
Drift sands, though generally poor in nutrients and often devoid of organic matter,
usually hold moisture well. Even in very arid areas, where annual rainfall seldom exceeds
200 mm and is confined to a short rainy season, the sand remains moist at depths of 50 - 60
cm although the surface layers become desiccated by evaporation. An exception is free
draining sand, where water percolates rapidly through the soil and under extreme conditions
the available soil moisture is insufficient to support tree establishment. The basic
problem in drift sand afforestation is to fix the moving sand for periods long enough for
the young trees to become established. Once established, the plantation is able to provide
its own shelter effect within the planted area and in course of time to enrich the sand with
the humus from decaying leaves, providing of course, that sand from outside the area is
prevented from engulfing and burying the young plantation. Sand drift stabilization,
therefore, involves attempting to provide barriers or windbreaks at the windward source of
the drifting sand and thereafter to prevent the sand from movements caused by eddies and
turbulence within the zone sheltered by the windbreaks.
Fortunately there are periods during the year in most sand drift areas when the
sand is not in movement, when high winds are lulled or when heavy rains give some temporary
cohesion to the surface layer. Such periods of rest may be of sufficient duration to
encourage the survival of indigenous vegetation, which can spread fairly rapidly over the
surface once shelterbelts are provided, aiding considerably in the processes of stabilization.
-100-
In very favourable conditions where regular, well-defined high wind periods are
interspersed with relatively long intervals of heavy rains and warm temperatures, it may
even be possible to stabilize moving sands simply by planting trees of well-adapted, fast-
growing speoies during the wind free periods. Suoh appears to be the oase in the coastal
sand-drift areas of southern Viet Nam, where the dunes can be stabilised by planting rows
of Casuarina without the necessity of employing any other special fixation techniques.
In general, however, tree planting cannot be successful unless special measures
are first taken to prevent or reduce sand movement.
Sand-Drift Fixation Methods
The first step in sand fixation is to identify the sources of the blown material
and, if possible, to create barriers to prevent or check any further invasion of this
material. Suoh primary barriers or shelterbelts will normally have to be repeated in
series at intervals downwind from the source area in order to create sheltered zones where
the main force of wind is broken up into turbulent eddies having only a localized action
on the surface. The second stage in the stabilization process is to protect the surface
from this relatively localized scour and deposit effect of air turbulence within the
shelter zones. This secondary protection can be achieved by a variety of methods which
act, in effect, as surface mulches.
Primary Protective Barriers
Where coastal beaches are the source of the blown sand, the normal practice is to
form a littoral dune along the shoreline. This is done by erecting a continuous but
permeable fence of posts, fascines or any other material convenient to the site. As the
blown sand accumulates and buries the fence a similar fence is constructed along the top
of the dune on the windward side of the crest, and as this is buried in sand a third may
be constructed and so on. In a few years littoral dunes can be built in this way up to
10 metres in height. If necessary, several parallel lines of dunes can be constructed
along the coast, and the hollows between them stabilized and planted with ground vegetation
and belts of trees to form a first line defence against the invading sand. The speoies
used in the first shelter belt should be windfirm and tolerant of salt spray carried in-
shore by the wind.
At Waitarere, New Zealand, a belt of Pinuc radiata stabilizes coastal sand dunes
and protects adjoining agricultural land. Marram grass was planted on these dunes
_--.-_- ._ ^ _i j.^ /XT-.. f7^1~J Tn~^4. C3-.^r^^^ ^V.^4./^
-101-
The sources of windblown sand forming continental dunes are often less simple to
control than in the oase of maritime dunes. The sand may be pioked up from wide stretches
of cultivated plains or y as in the oase of North Africa, from rainless deserts, such as
the Sahara* The logical first step, therefore, is to try to remedy the conditions causing
the exposure of the soil to wind action. This may be accompli shed by stubble mulching in
grain growing areas, by controlling excessive grazing and by systematic planting of wind-
breaks in the farm and pasture lands where the topsoils are liable to wind erosion. Even
where such measures are not possible, as in the Sahara, it may be feasible by systematic
reconnaissance to discover points where the topography causes "wind-funnel ing 11 effects*
A range of hills may form a barrier to the drifting sand whioh, however, succeeds in
penetrating the barrier at some low-lying point or where streams or torrent beds have out
passages through it. Such points offer possibilities for stabilization by the formation
of protective dunes across the direction of the wind using methods similar to those for
littoral dunes.
The main objective in creating such barriers or shelterbelts is to reduce the
force of prevailing winds to less than 18 - 25 km/h, whioh is the threshold velocity at
which soils begin to move. A great deal of the information acquired in the course of
investigations of tree windbreaks in different parts of the world is applicable to drift
sand control and stabilization. In general terms these effects may be summarized as
follows:
1) The distance that protection extends to leeward is proportionate to
the height of the windbreak; when wind direction is at right angles
to the line of the barrier, wind speed to leeward is reduced signif-
icantly for distances up to 20 times the height of the barrier. The
percentage reduction of wind speed varies also with the density of
the windbreak and with the distance to leeward. There is also a zone
of reduced wind speeds to windward, varying from twice to five times
the height of the windbreak;
2) Wide windbreaks are not necessarily more effective than narrow ones;
best results are obtained with those whioh are about as wide as they
are high;
3) Evaporation is greatly reduced in the lee of windbreaks, owing to
reduced air movement and temperature and increased atmospheric
humidity. Evaporation may be reduoed for a distance extending up to
24 times the height to leeward of the windbreak. The reduction is
proportionate to windbreak density, so that a permeable barrier,
especially with a sparse lower level, is not as efficient as a dense
one in reducing evaporation. This effect is of particular importance
in afforesting sand drift areas in hot, semi-arid regions*
Surface Stabilization Methods
Even within the shelter afforded by littoral dunes or windbreaks, wind velocities
may at times, and in some places be high enough to cause sand movement. The effeot of
such movement, or sand blast, can be very damaging, especially to newly-planted trees.
Eddies of wind may cause localized scouring and deposition so that some of the young trees
are either uprooted or are buried in sand. It is, therefore, almost always necessary to
blanket the whole area with some sort of mulching or a network of small windbreaks capable
of stopping the sand from blowing. In recent years a technique of mulching the surface by
spraying with Bitumen emulsions shows considerable promise of success and has been widely
used in certain parts of the world.
-102-
Clasaioal Methods
The method in most general use is to cover the whole area with a ohequer-board
pattern of minature windbreaks, whioh may o on si at of stake and wattle fencing made of out
branches or of stiff-stemmed grasses or canes. Sometimes the fences consist of living
plants* These fences or hedges vary in height from 0.5 to 2 metres and may be spaced
apart from as much as 40 metres to as olose as 2 metres, in the latter case only one tree
is subsequently planted in each square* When wider spaoings are employed, it has sometimes
proved necessary to cover the surface of the ground with branches, straw or grass cuttings
to give additional protection. Sometimes a surface covering of branch wood is sufficient in
itself to stop sand blowing without the need to construct the squares.
In Tunisia all the methods described are used. In spite of the protection of
littoral dunes, the maritime dunes are covered with a network of fencing made of out
branches from adjacent maquis forests. Live hedges of Saooharum aegyptiaoum are planted
in squares of 15 m or 20 m and the soil is then mulohed with a layer of branches. Li Cyprus,
on the other hand, a simple covering of branches was found sufficient protection for
plantations of Acacia oyanophylla to survive the first year, after whioh the plants
provided sufficient cover to protect the site. Where conditions ore not too severe, direct
planting of "stumps" of Acacia oyanophylla has succeeded in establishing a cover without
the need of other fixation measures.
This classical method of fixing dunes is usually costly, especially if cut branch-
wood or out grass is not available olose to the areas to be stabilized. Even where
available the large amounts required may mean denuding one area to protect another.
Fixation methods using live grasses or tree cuttings often delay the planting of main crop
species while waiting for vegetation or hedges to grow enough to stabilize the surface, and
once having done so, their roots may spread so far into the intervening space as to compete
seriously with the forest trees. Hedges and fences in closely spaced squares also impede
the movement of men in the area, especially at tree planting times, and inevitably fences
get damaged so that gaps appear causing localized "wind funnel" erosion.
Dune Spraying Techniques
Spraying shifting sand with fuel oil or bitumen products has been used as a method
of fixing blown sand in many countries. Such products are used in the United States and
Kuwait, for example, for protecting highways against encroaching sand, and in India and
Pakistan for fixing dunes whioh fill up irrigation canals. In recent years spraying drift
sands in connection with afforestation has been developed on a relatively wide soale in
Libya and Tunisia. The type of bitumen product used in these countries is available from
most of the oil oompani 3. The Pakistan Irrigation Research Institute has recently
investigated the stabilizing efficacy of certain of these proprietary products as compared
to some similar laboratory-prepared bituminous emulsions. These latter consist of bitumen,
potassium hydroxide and potassium carbonates with stearin pitch, vinsol resin soap and 5#
bentonite slurry emulsified in water at 95C When sprayed on sand such emulsions penetrate
the surface layers and dry rapidly to form a crust on the surface which gives complete
protection against wind. The depth of penetration varies to some extent with the product
used, with the proportion of water in the mixture and with the quantities sprayed per unit
area. To be effective, penetrations of 1 to 3 om must be obtained. The spraying also has
the effect of increasing the load bearing pressures of the sand by up to 20 - 30 tons per
square metre.
In Libya one company, working on contract for the forest service, has sprayed
several thousand hectares of dunes, and similar techniques have been tried in Tunisia.
Initially conventional tank trucks were employed whioh were especially equipped for desert
use to carry the oil into the areas to be afforested. The compound was then sprayed over
the sand by hand operated lanoe sprays. To sped up the work the company developed a
special vehicle, a steel sled fitted with an 800 litre tank and wide spray booms, whioh is
towed or winched over the dunes by bulldozer. Li this way, the spraying equipment can
-103-
surmount the most difficult dune terrain leaving behind it a sprayed strip 25 metres wide*
Eaoh vehicle oan oover about 4 hectares a day and uses approximately 4 000 litres of the
oil product per hectare* In Libya the spraying was found to have toxic effects on some of
the plants used (generally Acacia and Eucalyptus) so spraying now precedes planting. This
also enables spraying to be carried out in seasons unsuitable for planting* In Tunisia
trials with the same bitumen product indicated that spraying after planting is more
praotioable y since it was not harmful to the young plants (Acacia and Pinus). In areas
sprayed before planting the movements of the men planting and carrying plants to the
planting sites caused so much disturbance to the stabilized surface crust that its
protective effects were greatly diminished.
Continuing experience will certainly bring improvements in spraying techniques and
in the formulation of the stabilizing products used* Combined with the advantages of speed
and lower costs, it seems likely that spraying techniques will tend to replace the classical
methods of dune fixation. This tendency is likely to be accelerated if experiments in Libya
for air-spraying a new type of chemical stabilizer are successful. This stabilizer is a
chemical adhesive compound which coagulates when it absorbs moisture and forms a thin
stabilizing layer over the surface of the dunes. Seeding of the areas from the air at the
same time as the chemical stabilizer could mean a complete revolution in the techniques of
afforesting drift sands. Early records indicated that spraying techniques were more oost
efficient than the olassioal method of dune fixation.
WET OR WATERLOGGED SITES
Wet sites are those in which the soil is waterlogged for the whole or the greater
part of the year and oan only be afforested if the land IB drained.
The vast areas of swamps and fens, supporting natural self-regenerating forests of
hydrophytic species of economic value f which occur both in the tropical regions and in the
boreal coniferous zone are excluded from consideration here since the tree species have
themselves evolved ways of overcoming the difficulties inherent in this environment.
However, there are also equally vast areas of swamps and peat lands which are entirely
treeless or only carry an arboreal vegetation of low^-value species. According to some
estimates this area is as great as 200 million hectares. A large proportion of this area
could, after drainage, be afforested with species of high economic value.
Apart from these large expanses of bog land, the forester is often faced with
relatively small marshy lands occurring as sub-sites in a larger afforestation project
on well drained soils. Such local sites may occur in small depressions or on alluvial
flats adjoining the banks of rivers, and their drainage may be required as part of the
general afforestation plan.
Whether waters-logging is a characteristic of the whole area or only of some
relatively small section, the techniques for draining away the water and rehabilitating
the soils are essentially the same.
Sites Where Drainage is Practised
Marshes with Free-Standing Water
Before soil drainage or soil drying oan be undertaken, standing water on the
surface must be evacuated. This requires knowledge of the origins of the water coming
into the marsh and the reasons for it collecting and stagnating in the area.
In the oases where the water flows from higher land it may be possible, under
certain topographic conditions, to intercept the flow at some suitable point above the
level of the marsh and to divert it to a cut-off drain or canal leading into some natural
drainage channel.
-104-
Riparian marshes created by periodic inundations of a river in flood can only be
drained by constructing bunds or embankments capable of keeping flood water from entering
the riverside flats. It may then be necessary to construct a series of drains in the marsh
to dry out pools left in old flood channels or to cope with water entering by underground
seepage from the river bed. If, as is sometimes the case, the topography does not allow
the evacuation of these drains downstream by gravity flow f it may be necessary to
concentrate such water in a sump pond whence it can be pumped back into the river channel
over the protecting embankment.
Similarly with lagoon type marshes bordering the seashore, sluice regulators are
required on all outlets to the sea, to be closed at high tides and opened again at low
tides to allow the marsh water to drain out to sea. Suoh regulators may be closed by an
automatic device, actuated by the rising tide water levels.
A marsh may sometimes owe its origin to the presence of an obstruction to its
natural outlet channel caused by geographical faulting, or by land slips or falls of rock.
Many upland marshes exist as the relics of former lakes and drowned valleys formed by
geological upthrusts damming in the valley. In time, the natural spill-ways are eroded
away, gradually lowering the level of the lake water until the water becomes shallow
enough for marsh formation. These marshes can be drained by cutting a channel through the
obstructing barrier or by tunnelling through it, always assuming the costs are not
excessive in relation to the area to be reclaimed.
Some marshes are formed on the low-lying shores of lakes as a result of periodic
rises in the lake water level following heavy rains. These can be reclaimed by constructing
embankments above the highest water mark of the lake and subsequently draining the marshes
by pumping or by the use of regulator sluices on the drain outlets to the lake.
A similar method is employed extensively in low-lying areas in the Paran delta in
Argentina for reclaiming land which is periodically covered to shallow depths by flood
waters. Here the marsh lands are encircled by bunds and then drained by pumping, forming
a series of reclaimed islands which are then afforested. In the dry season, the pumps are
used to pump water in the reverse direction from the deeper marsh water channels for
irrigating the plantations.
Peat Bogs and Qley Soils
Poorly drained peat soils occur mainly in those regions of the world where annual
rainfall greatly exceeds evaporation and where temperature is sufficient for a rich
production of organic matter but too oold for its rapid decomposition. Under such climatic
conditions, an accumulation of plant remains and the formation of peat is common. In
addition to climatic factors, level topography and poor water permeability of the subsoil
favour bog formation. Swamps and other waterlogged soils are, therefore, fairly common in
flat lowlands even in tropical and subtropical climates, although owing to more rapid
decomposition in warmer areas, true peat may be missing. On the other hand, under
extremely humid and maritime conditions bogs with thick peat deposits can exist even on
quite steep slopes, as in parts of Scotland and western Norway.
Waterlogged mineral soils with little or no peat formation also occur in conditions
of impeded soil drainage. These are usually heavy clay soils and exhibit the typical
mottling discoloration associated with gley soils. Poor drainage may be due to an
impervious substratum or to the presence of a podsolized or laterized hardpan.
Even in waterlogged soils the uppermost horizon may be sufficiently aerated to
support a ground cover of mosses and other water-loving species; in some oases, this
layer may be deep enough to support trees, though these are often deformed with very
shallow root systems and liable to windthrow. Early attempts in Great Britain to afforest
peat bogs after constructing shallow surface drains proved that the tree crops, while
making good growth in the early years, could not withstand strong winds during the pole stage.
-105-
It is essential to achieve an aerated layer of topsoil at least 30 om deep, preferably
deeper* To achieve this, drains must be out considerably deeper to allow for the effects
of what is known as the "capillary fringe 11 . This is in effect a waterlogged zone whioh is
formed due to capillary forces just above the level of the true water table or above the
level of surface water in the receiving drain. This capillary fringe can sometimes reach
as much as 30 om upwards, whioh explains why shallow drains sometimes appear to have no
effect on waterlogging. To allow for this capillary fringe, receiving drains should
therefore be at least 40 - 60 om deep, and even deeper to ensure the formation of a
sufficient layer of fully aerated soil for root development.
Salines and Salt Marshes
Waterlogged soils and marshes occur where high salinity is an additional limiting
factor to soil wetness. Salt or brackish marshes formed along the coasts and subject to
inflows of sea water are found in many parts of the world. In arid climates, salines can
result from the evaporation of salt-bearing spate flows impounded in inland depressions.
Though there are some tree speoies of economic value, e.g. Rhizophora spp. ,
Tamarix artioulata, Prosopis tamarugo, and the date palms, whioh tolerate a high degree of
soil salinity (and in the case of the mangroves, marshy conditions as well), the
afforestation of salines is impossible unless the land is both drained and the salt content
of the soil reduced or removed by leaching with large quantities of fresh water. This may
be feasible in situations where the saline is capable of being drained, so that flood waters
entering oan be used for washing the salt out of the soil or where irrigation, combined with
drainage, may achieve the same effect. Desalination, however, is almost always a very
oostly undertaking and oan seldom be justified for tree crops alone. Further mention is
made of this matter in the section dealing with irrigated plantations.
Where permanent drainage is not feasible, the only alternative is to construct a
series of alternating mounds and ditohes, the soil being excavated from the ditches and
spread on the intervening mounds whioh become plantable once the salts have been leached
out over a period of time by local rainfall. 3uoh mounds should be large enough to provide
adequate growing space for the expanding tree root systems above the highest level of
fluctuations in the water table. This again is a very oostly operation and oan seldom be
justified on economic production criteria.
In fact foresters would be well advised to avoid trying to reclaim marshy areas
where the difficulties of site preparation are further complicated by high salinity.
Drainage Techniques
Drain Characteristics and Layout
For planning the layout of the drainage systems in marshes or waterlogged soils,
a detailed topographic survey of the area is necessary. Also, in waterlogged soils, or in
marshlands from whioh free-standing water has been drained, soil formations should be
examined carefully so as to identify the type of soil, the depth of any peat layers or the
presence and depth of any hardpan formation. Chemical analyses of the soil are needed as
a guide to possible fertilizer treatments.
Experimental plots should be established to test the drainage efficiency of
different intensities and depths of drains by measuring the movement of the water level
in pits located between the drains.
-106-
On waterlogged sites, drainage ditches must be constructed prior to planting of
most species. The photo shows a vigorous pine stand in Queensland, Australia.
(Courtesy D.A. Harcharik)
Three types of open drains are recognized*
drains f and evaouator drains.
Cut-off Drains
cut-off drains, receiving or collector
Cut-off drains are designed to intercept water entering the marsh and to lead it
to some other line of natural drainage y thus by-passing the swamp. The dimensions of a
cut-off drain should be large enough to take the maximum flow of water entering the marsh
in times of heavy rains or of floods.
Collector Drains
Collector drains are those which actually receive the water seeping from the soil;
the spacing between collector drains must therefore relate to the percolation rate of
water in the soil* The heavier the soil, i.e. the higher its clay content, the slower the
percolation rate and, therefore, the shorter the distance between drains. Peat also holds
water tenaciously, which means that sites with deep peat layers need very intensive
drainage works. On sloping terrain, collector drains should be aligned as far as possible
along the o on tour, allowing juert enough downward inclination to induce a flow into the
main evaouator drains. In this way the maximum interception is obtained for a minimum
length. A drain aligned at a more pronounced oblique angle across the slope will have a
steeper gradient and a longer length for the same interception, while a drain aligned at
right-angles to the contour loses its interception capacity entirely.
-107-
The oross section dimensions of collector drains will be determined largely by the
type of soils encountered, but normally they would be at least 40 om and possibly as muoh
as 1 m deep. The top width of the drain should be at least as great as the depth, and the
sides which slope down to the bed should not be less than 20 om deep and not less than 30
om in peat to allow for the tendency of these soils to close.
The gradient of the drains (i.e the downward inclination of the bed of the drain
towards the discharge point) should be between 0*25 and 30$. Below 0.25$ there is a
danger of excessive silting and above 3.0$ there is the risk of scouring and erosion unless
the bed is out in very resistant soil formations. The required gradient can be obtained
either by gradually deepening the drain or f on sloping land, by aligning the drains at an
oblique angle to the contour without varying the depth of the drain. This is the method
used when drains axe constructed by fixed depth draining ploughs.
The length of collector drains should in general fall between 50 and 100 m as in
longer drains there are more chances for error in gradient, especially when encountering
changes in the direction of the slope. Moreover, the longer the drain the greater the
risk of excessive accumulations of water in times of heavy rains.
The distance between collector drains will vary according to the soil type
encountered and also the slope of the terrain. As already stated, in general the heavier
the soil the closer the drains should be to one another. The standard distances between
drains on gley and peaty-gley soils adopted by the British Forestry Commission is 7 m on
slopes up to 5$ 10 m on slopes between 5 and 75$ and 135 m on slopes above 75$ On
less heavy soils, as for example the peaty podsols which characterize certain upland heaths
in Great Britain, the spacing can be doubled.
In Sweden, Finland and Russia drains are generally wider apart. In these countries
when the drainage of peat bogs was started, drains were constructed 80 - 120 m apart and
1.0 - 1.5 m deep, but experience suggested that these distances were too great to secure
efficient drainage. In later years when a change over from manual to mechanized drain
digging became possible, distances have been reduced to 20 - 30 m between shallower drains
of only 40 - 60 cm depth. On sloping terrain and particularly on waterlogged mineral soils
with thin peat layers, the British system of relatively closely spaced drains has been
introduced with success. Determining the economic optimum suggests that narrower spacings
be used on level swamps than on swamps which are sloping and that wider spacings should be
chosen on poor sites and narrower spacings on good quality peat lands.
Evaouator Drains
Collector drains discharge into evacuator drains, whose function is to convey
drainage water to some point where it can be disposed of either by discharge into some
natural water course or by pumping.
The layout of the system of evacuator drains should be designed to tap as many
collector drains as possible. Experience indicates that this is most likely to be achieved
by the so-called 'herring-bone 1 layout with a central main evaouator drain and branch
collector drains taking off on both sides.
The dimensions and gradient of evaouator drains aw normally greater than those of
the collectors; their design should be sufficiently generous to accommodate exceptional
flows in times of heavy rains. Their cross-section resembles the truncated V-form of the
collector drains.
-108-
Other Forms of Soil Drainage
In oases where waterlogging of the soil can be attributed to the presence of an
impermeable hardpan, it may be possible to drain the land by breaking up the hardpan with
subsoiling implements, enabling soil water to percolate downwards through the breaches in
the hardpan. This has proved possible in certain types of coarser textured soils over-
lying pods oli zed hardpan in upland heath moors in Scotland.
The effectiveness of drainage work can sometimes be improved by mole ploughing
(see page 1 09 ), especially in stiff clay soils free of stones. The opening of subsoil
drains in this way can speed up the action of collector drains, and in favourable
circumstances mole ploughing directly into evacuator drains enables the collector drains
to be more widely spaced or to be dispensed with altogether. The British Forestry
Commission is now experimenting with some success with the use of a special forest mole
plough capable of opening a subsoil tunnel drain in peat beds. This plough extrudes a
ribbon of peat 38 x 20 cm leaving only a narrow slot at ground level.
Drainage Machinery and Implements
The opening of drains by hand, though still used on sites too small to warrant the
expense of machinery, has by now been superseded in most situations by mechanized methods.
Nowadays, there exists a great variety of drain digging machines, but the two types found
most convenient in forestry drainage work are the drainage ploughs and the hydraulic type
excavators mounted on wheeled or crawler type vehicles.
Drainage Ploughs
In peat and other soft soils free from large stones, ploughs provide by far the
cheapest method of forming drains. The most usual type in use is the double mould-board
drainer drawn by a tractor or by a tractor and winch. This plough cuts a V-shaped drain
throwing the soil on both sides of the drain. If short wings are bolted to the top of
the shares extending laterally and slightly above the soil level, the soil thrown by the
shares is pushed well clear of the drain edges, thereby reducing the amount of soil falling
back into the drain.
Single share mould-board ploughs are less often used than the double share drainer,
but they are preferred in certain circumstances. For example, when cutting contour drains
on sloping surfaces it may be desirable to throw the soil out on the downhill side of the
drain furrow. In the United Kingdom the single share plough is used extensively for
making shallow (20-30 im deep) drains in peaty soils, though the main object of the
operation is to provide ridges of peat turves on which the trees are planted. The plough
furrows of course also help in draining surface water in times of heavy rain, but they are
not normally deep enough to dry out the soil, mainly on account of the effects of the
capillary fringe, of which mention has already been made. The British Forestry Commission
has developed modifications of this plough capable of cutting deeper drains, some as much
as 90 o m deep* These have shown certain disadvantages compared with the double share
drains:
1) The full depth of drain is rarely achieved in practice because the
enormous side-thrust exerted by the single share in lifting and
turning the continuous ribbon of peat forces the plough body up the
batter on the side opposite to that on which the soil is placed.
This produces an uneven, undulating bed to the drain and results in
an uneven edge and batter on the side free from the thrust. A
double-share drain, however, maintains a full and constant depth,
and the downward thrust of the soil acting equally on both sides
results in a better shaped and more stable drain.
-109-
2) On mineral soil, where a hard or gravelly layer is sometimes
encountered, the same trouble occurs. The single mould-board
plough tends to ride up over the harder parts of the subsoil
producing- an uneven and ragged drain.
3) The single share plough cannot be used to deepen and clean
existing drains like the double mould-board drainer*
Ploughing on waterlogged soils usually requires specially designed wheels or tracks
for the tractor pulling the plough as well as for the plough itself if loss of traction or
bogging down is to be avoided. Wheels and/or tyres are available with a wider tread, or
double tractor wheels oan be used. Pour- wheel-drive tractors, although more oostly, have
advantages over normal drive tractors under such conditions. Crawler tractors oan be
fitted with tracks wider than the standard. Ploughs for wet soil should be fitted with
steel drum wheels or tractor type wheels.
In Finland, Sweden and northern Russia, peat lands are drained using very heavy
(4-6 ton) drainage ploughs drawn by crawler tractors of 9 - 18 tons using a winch. These
heavy machines have been found superior on sites where the land to be drained consists of
swamps with a thin peat layer containing logs and stumps and with a subsoil which is often
rocky.
Mole Ploughs
The mole plough is essentially a single-tine sub-soiler, the digging point of the
tine being replaced by a squat torpedo-shaped head, called the mole. In operation this
mole opens a tube-like passage through the soil, starting from the drain bank or outlet
point and being drawn up slope. Mole ploughs are directly mounted on a tractor, fitted
with an Edes linkage which enables a graded channel to be achieved in spite of minor
surface irregularities.
Mole ploughing is only effective in even textured clay soils free of stones, but
in such circumstances it is the cheapest way of draining the soil. Modifications of the
mole using a 15 cm expander have been used in peat soils to speed drainage of water to
open collecting drains, and as mentioned earlier, the British Forestry Commission is also
experimenting with special mole ploughs for subsoil draining in peat bogs.
The main disadvantage of mole-draining is that the drains cannot be cleaned, so
that once they are clogged, the work has to be completely redone.
Excavators
A great variety of excavating machines are available but most fall into three
categories: dragline excavators, hydraulic excavators and continuous action machines.
Dragline Excavators
Dragline excavators have large excavator buckets operated by machine winches.
Draglines are mounted on wide crawler tracks and are particularly suitable for operation
on soft or boggy sites. Working on mats further increases stability on soft sites.
Dragline excavators oan be used for virtually all types of drainage construction
and maintenance work. Their advantages lie 1) in their ability to work on wet sites,
2) in the long reach provided by the boom, which also enables soil to be spread over a
wider radius and 3) in the versatility possible in the size and oross-seotion dimensions
of the drain excavated* On the other hand, they are less mobile and more clumsy to
handle than the hydraulic excavators whioh are generally less expensive in operation.
-110-
Hydraulic Excavators
With these machines the excavating bucket is attached to the end of a short
articulated boom and is operated by hydraulic pistons. The excavators are mounted on
crawler or wheeled tractors. Most types are fitted with a dozer blade loader which,
apart from occasional use for loading, and the advantage of being able to remove soil
banks and other obstructions, is necessary for crossing wide ditches and also serves
as a stabilizer.
The wheeled type excavator can be used on most wet mineral soils, but on peat
and very soft soils a crawler tractor is essential; it should be fitted with 76 cm
tracks or wider. Hydraulic excavators can be used for making drains of those widths
and depths commonly used in forestry and can also be used for drain maintenance in wide
drains, the machine operating from opposite banks of the drain.
For drain maintenance and cleaning a form of lightweight excavator mounted on an
ordinary agricultural type wheeled tractor is available.
Continuous Action Machines
These are excavators fitted with dredging^-action chains of buckets or scrapers or
with a rotating helix. Experience has shown, however, that these machines have several
limitations compared with other types of draining implements regarding the depth and
shaping of drains, while most have difficulties in operating in soil where large stones,
stumps and roots are encountered. In general it can be said that drain ploughs or
hydraulic excavators can do the same work more efficiently and more cheaply than
continuous action excavators.
Post Drainage Site Preparation
Surface Cultivation
Drainage alone is not always a sufficient amelioration of soil conditions for
successful afforestation. In some oases, the porosity and aeration of the soil of drained
marshland must be improved by ploughing, and this may have to be preceded by the destruction
of herbaceous and arboreal marsh vegetation. Wherever possible this vegetation should be
burned and the phosphorus and potassium rich ash ploughed into the soil. If further soil
cultivation is unnecessary, seedlings can be notched directly into the drained land. This
is the general practice in Finland, but direct broadcast sowing of pine seed is also used
to afforest drained peat bogs. In the United Kingdom, direct planting or seeding on
drained peat bog has only limited success and the method of notching plants into the turves
turned up by ploughing along the planting lines is more commonly used. This method also
has the advantage that the strip of over-turned soil retards the growth of competing
vegetation for sufficient time to allow the young plants to become established. In warmer
climates such advantages of turf or ridge planting are likely to be short-lived on account
of the more rapid growth of weeds. A large plough ridge may even prove an obstacle
impeding the passage of harrows or rotavators used in subsequent inter-row weeding and
ground cultivation work.
Bedding, or the creation of lined mounds, either alone or in conjunction with
excavated drains is also used to improve drainage and facilitates planting on wet sites
in the U*S.A As described on page29, bedding is carried out by heavy duty disc harrows
(of the types described for pioneer ploughing) which are set to throw the soil inwards to
form a mound, that elevates the planting bed above the general level.
-111-
Fertilization
Drained marshland coils often show deficiencies in soil nutrients as well as
having a strongly aoid reaction. Salines on the other hand may often be strongly alkaline
as well as being deficient in nitrogen and other soil nutrients. Where the peatlands have
not been classified into identifiable types, careful chemical analyses of the soils should
be made at an early stage before afforestation to identify which nutrients are in deficiency.
Fertilizer trials should also be carried out to determine suitable techniques and
application rates to restore soil fertility levels and promote vigorous tree growth.
Nitrogen is usually abundant in marshland soils, though often in an insoluble
organic form, but drainage and the addition of mineral fertilizers usually increase the
rate of nitrogen mobilization to such an extent that additional nitrogen may not be
necessary.
Phosphorus is the nutrient which often constitutes a limiting factor in peat and
gley soils, and on most sites the addition of phophorus has produced a marked response in
tree growth. In the United Kingdom and Scandinavia phosphate fertilization in peat bog
afforestation is a standard practice. Fertilizer is applied at the time of planting;
ground rook phosphate or basic slag is used, particularly when application is by machines,
but superphosphate or triple superphosphate is used when application is by hand. Combined
phosphorus and potassium fertilizers containing 16.5$> each of P and K are also used in peat
bog afforestation.
On very acid soils, heavy liming is often beneficial; the lime improves the
physical properties of the soil and reduces soil acidity, thus promoting nitrogen
mobilization. Alkaline soils with a high sodium chloride content can, under some conditions,
be improved by the addition of ground gypsum; i.e. by replacing the sodium by calcium.
MINE TIPS AND SPOIL SITES
Industrial activities, especially those concerned with the mining and the
metallurgical industries, often produce areas of waste land where unwanted material is
dumped to form mine tips, slag heaps or slurry ponds. These areas of industrial waste
land leave unsightly scars which come to be resented by the inhabitants of the area, and
often pressure is brought on the authorities concerned to reclaim the areas or to screen
them with a green cover of vegetation or tree plantations. Sometimes it is possible by
afforestation to create parks of amenity value for neighbouring urban populations or to
restore productivity to the affected areas.
In many man-made industrial waste lands, site factors inhibiting natural
revegetation from seeds blown in from neighbouring unspoiled land are present. They are
directly linked to the type of mining or industry concerned, which allows industrial
waste lands to be classified into a number of categories, as described in the following
sections.
Types of Industrial Waste Lands
Strip Mining Waste Lands
In strip mining, topsoil and rook overburden are scraped away to expose the coal
or mineralized strata required for industrial processing. After mining, the resulting
waste land may consist of crater-like cavities alternating with dumps of material from
the overburden which vary in texture from former topsoil to broken rock waste with little
or no earth.
On hilly sites mining will usually have been worked on the contour, resulting in
a series of rock terraces and steep scree banks where the overburden has been tipped
downhill.
-112-
Where the dumped material contains 20 percent or more soil, revegetation by seeds
and spores blown in from neighbouring unspoiled land may occur soon after mining operations
oease f indicating a potential soil fertility suitable for direct afforestation. Elsewhere
the exposed rock strata and dumps of rooky material and stones, often compacted by the
passage of the heavy earth-moving machinery, must await the slow process of soil formation
through exposure to the atmosphere and reshaping by wind and water erosion. Absence of
humus and nitrogen is typical of most of these sites in the early stages.
Site preparation for tree planting consists ideally of reshaping the waste area
with earth-moving machines, filling in cavities and levelling or smoothing down the dumps
before finally covering the whole area with topsoil. Preferably the soil originally
covering the land should be used, if this has been segregated in special dumps, or soil
may be imported from elsewhere. Such work is very costly, but in some countries
restoration of the site is an obligatory condition of the mining licence.
If reshaping is not possible, afforestation can be started on areas colonized by
natural vegetation, while in the remaining still sterile areas, trees of hardy pioneer
species oan be planted in larger holes to which imported soil has been introduced. In
areas such as brick fields, the derelict excavations are often filled with water, to
provide artificial lakes for recreation, and tree planting for amenity is confined to the
lake shore areas.
Colliery and Deep Mine Tips
Waste spoil from underground mining operations is usually brought to the surface
and tipped in large heaps or flat-topped spoil banks. High tips and conical or table-
mountain forms of spoil heaps usually have steeply sloping unstable sides, thus they
are subject to land slip if the foot of the heap is undermined by a stream or by drainage
water impounded or trapped in the complex configurations resulting when the spoil heaps
encroach upon or block drainage runways. These tips consist of crushed and sometimes
pulverized rook and are characterized by sudden changes in particle size depending on the
source of material being tipped, but the material is very porous, permitting the easy
penetration of air and rainwater and also of plant roots. The material, however, cannot
be described as soil and will remain sterile until the rock particles are weathered and,
in course of time, become colonized by soil forming organisms and eventually by pioneer
vegetation.
Preparation of such sites for afforestation involves first of all stabilizing
measures to minimize I'xnd slips and erosion. This may involve building walls at the foot
of tips encroaching on natural water courses to prevent water eroding and undercutting
the slope and, if necessary, canalizing the water courses in masonry chutes or concrete
conduits. Ponds of trapped water within a complex of tips should be drained away if there
is danger of collapse due to erosion in subsurface drainage channels. The flat tops of
some spoil heaps oan be re-soiled, but the slopes may have to be contour trenched or
terraced and imported soil filled into planting holes.
Access roads should be constructed before afforestation and care taken to dispose
of road drainage water in ways which minimize soil erosion and ravine formation in the
relatively soft tip material.
For the first rotation it will generally be advisable to plant hardy pioneer
bushes and trees capable of adapting to the severe limitations of the site, thereby
creating better soil and microclimatio conditions. The second rotation of trees oan be
of greater economic value, and oan sometimes be introduced by underplanting the pioneer
crop.
-113-
Meohanioally Treated Waste Lands
Li some industries the use of crashers, mills and washing plants produces finer
grain particles in the process of separating the coal or metal ore from the waste. Many
fine waste materials, for example, the losses in lignite strip mines, or the waste from
"bituminous coal preparation plants, oan be suspended in water and pumped in pipelines to
embanked basins or to slurry pits, where they settle, forming flat new areas. These flat
fields of water-sedimented loess are very fertile unless rendered toxic to plant growth
by the accumulation of noxious compounds from the rapid oxidation of sulphide particles
at rates faster than the rate of leaching. In such cases, thp land will remain sterile
for long periods unless some form of flood irrigation with subsoil drains oan be used to
wash the salts out of the soil.
If fine material is tipped, the danger from land slips will be accentuated unless
stabilizing techniques similar to those mentioned in the preceding section axe employed.
Chemically Treated Waste Lands
The huge group of chemically treated wastes can be classified into burned and
unburned material. Burned material, for example the ash and slag from power stations,
consists of oxides, silicates and sulphates of iron, aluminium, calcium, magnesium,
potassium and sodium. As a result of their content of free bases, most of these ashes
possess a high alkalinity and salt content, which may initially prevent plant growth.
Leaching of the soluble salts and reaction with atmospheric carbon dioxide lessen their
toxic effect in time, unless the waste contains boron or other elements highly toxic to
plant life. Brick and clinker waste, broken glass and cement waste are further examples
of burned waste, but these usually contain less soluble salts than the ashes referred to
above.
Unburned chemically treated wastes are produced in metallurgical plants where the
milled ore is "floated" in order to separate the stone from the metal. Such wastes are
generally pumped out to sedimentation basins and to slurry ponds forming flat fields. The
flotation agents used for different ores can impart strongly acid or alkaline reactions to
the sedimented waste depending on the agent used, for example the cyanide flotation process
used for extraction of copper and iron ores can be mentioned in contrast to the alkaline
agents used in the gold mines of South Africa which give the waste a pH reaction as high
as 11.0.
The afforestation of chemically treated waste dumps cannot usually be attempted
until accumulation of noxious chemicals have been leached from the soil and the pH value
raised or lowered to the range tolerable to plant life ( pH 3.5 - 6-5). Natural leaching
processes can be accelerated by soil washing methods, though this adds considerably to the
cost.
Other Forms of Waste Material
The disposal of domestic refuse, especially from large conurbations, has in the past
produced large waste dumps consisting of both organic and inorganic materials. Generally
speaking, land covered by domestic refuse tips forms favourable tree planting sites so long
as they are free-draining. Where impeded drainage gives rise to anaerobic conditions the
soil may become toxic through decomposition of organic matter and the liberation of hydrogen
sulphide.
The dumping of waste products from synthetic chemical industries can give rise to a
more intraotible form of waste land. Synthetic material of organic origin can be destroyed
by burning, but waste salts and inorganic compounds must be tipped or sunk in deep porous
st rat a.
-114-
The Choice of Establishment Techniques
Before attempting to initiate afforestation on industrial waste lands f the forester
should make a detailed study of the limiting site factors. These will largely decide the
scope and intensity of the preparatory work required, the choice of species which combine
adaptability to raw soils with economic value, and the likely social or economic end results
of the planting effort.
Evaluation of the Site
The site should be examined to determine its actual or potential fertility. This
involves an investigation of the materials in the waste to origin and size of particles,
the topography of the tips, especially in connection with erosion and land slip hazards,
and the presence of noxious salts or chemicals. Where natural vegetation has already
colonized the waste area, a study of the component species may well indicate areas where
soil conditions approximate those suitable for a forest crop, as well as give information
helpful in the selection of the tree species to be used on different sub-sites or exposures.
Those areas avoided by natural vegetation may indicate the presence of limiting site factors
needing special treatment, and the pattern of colonization will certainly aid the work of
mapping the various sub-divisions or sub-sites in the area.
The Choice of Species
Except in those favourable cases where it has been feasible to cover the waste lands
with a substantial layer of fertile topsoil, the trees selected for planting will normally
be chosen from a limited list of species in each climatic range which have the capacity to
survive in largely raw soils and to enrich the soils gradually by adding humus and nitrogen.
The selection may well include a mixture of species, some destined simply to form an under-
growth or even an herbaceous soil stabilizing cover. Extremes in the soil pH values or the
presence of noxious salts may still further limit the range of choice. In all cases it
would be wise to establish a series of trial plots to find out which species are best
adapted to the site and which planting and fertilizer techniques give the best results.
Experience from such trials may indicate the possibility of planting the selected tree crop
directly or, where this is not feasible, show that some sort of nurse crop is needed to
improve the site for tree planting at some later stage. The importation of good fertile
soil, even if only enough to fill the planting holes, will almost always be needed in order
to inoculate the land with soil forming organisms and myoorrhizal symbionts.
Economic Considerations
The choice of treatment will be decided by cost, by the effectiveness of the
establishment methods, by the possible future value of the tree crop and by the ultimate
purpose or objectives of the reclamation.
Industrial waste land will rarely offer easy or inexpensive conditions for
afforestation, but there are plenty of techniques available for the improvement of tree
growing conditions. To recapitulate, some of those most commonly used in reclamation are:
1) Reshaping the contours in order to minimize erosion or to facilitate
future management;
2) Covering toxic or infertile material with soil or waste of better
quality;
3) Neutralizing strong acid or alkaline spoils by the use of lime,
sulphur, or waste of the opposite reaction;
-115-
4) Buffering toxic elements by the use of peat, humus f olay f or other
material with a high exchange capacity. Water holding capacity and
nutrient availability will be increased at the same time;
5) Leaching of salts f acids or alkalis by means of rainwater collected
by ditches and basins or by irrigation, on heavy soils accompanied
by artificial drainage;
6) Loosening the soil on compacted land or sulphide wastes by subsoiling
to provide better aeration;
7) Fertilizing with organic or green manures or with compound fertilizers;
8) Stabilizing the surface of waste tips of very fine particles by
agglutinating sprays or branch mulches and by constructing windbreaks
where aerial erosion is a problem;
9) By watering or irrigating the plants if this is necessary, to get them
well established after planting.
The costs of establishment may often be higher than the potential cash value of the
tree crop would seem to justify, but it is also necessary to assess certain intangible
benefits such as the improvement of amenities, the provision of recreation for densely
populated industrial areas, or the prevention of site deterioration. Control of further
site deterioration or degradation is often associated with protection against erosion,
consequent siltation and flooding of fertile down-streajn agricultural lands.
BIBLIOGRAPHY AND REFERENCES
Al'benskii and Nikitin, P.D. (eds.). Handbook of afforestation and soil melioration.
1967 Translated from Russian in Jerusalem by Israel Program for Scientific
Translation. 516 P
Atterson, J. and Binns, W.O. Peat nutrients and tree requirements in Forestry Commission
1975 plantations. In Peatland forestry: proceedings of NERC Symposium, pp. 127-
137-
Ayers, R.S., and Westcot, D.W. Water quality for agriculture. Rome, FAD. 97 p. Irrigation
1976 and Drainage Paper 29. t
Bay, R.R. Rehabilitation potentials and limitations of surface mined land. In Transactions
1976 of the 41st North American Wildlife and Natural Resources Conference, pp. 345-
355. Washington, D.C., Wildlife Management Institute.
Ben Aissa, J. Fixation et reboisement des dunes littorales en Tunisie. Jji Proceedings of
1967 FAO World Symposium on Man-Made Forests and their Industrial Importance, Vol.
2, pp. 1087-1097. Rome, FAO.
Bhimaya, C.P. Sand dune stabilization. Report to the Government of Iran. Rome, FAO. 32 p.
1971 FAO mo. TA 2959*
Bhimaya, G.P. Sand dune fixation. Report to the Government of Iran. Rome, FAO. 49 P
1974 FAO no. TA 3252.
Binns, W.O. Silviculture on drained areas: fertilisation. In Co-ordinators papers and
1974 discussions of the International Symposium on Forest Drainage, pp. 101-107.
-116-
Birot, Y. and Qalabert, J. Economic de 1'eau et travail du sol dans les plantations
1969-70 forestiires de zone siche. Revue Bois et Forets dee Tropiques, no. 127?
29-44? no. 128i 23-37; no. 129: 3-20; no. 130: 12-22.
Booher, L.J. Surface irrigation. Rome, PAO. 160 p. PAO Agricultural Development Paper
1974 No. 95.
Bosshard, W.C. Irrigation methods in Khartoum greenbelt. Forestry Research and Education
1966 Project, Sudan. Khartoum Forest Research Institute. 25 p. Pamphlet No. 21.
Bostanoglu, L. Cours d'amenagement des bassins versants. Demonstration et Formation en
1973 Amfoagement des Forits et des PSturages, Afghanistan. Rome, FAO. 187 P*
TO: SF/APa/67/5l5 f Document de travail.
British Forestry Commission. Peatland ploughing. Research Information Note 13E16/76/SILN.
1976
British Forestry Commission. Plough nomenclature and equipment* Research Information Note
1977 28/77/SILN.
Catinot, R. Sylviculture tropioale dans les zones sfcches de 1'Afrique. Revue Bois et
1967 Forets des Tropiques, no. 111: 19-32 and no. 112: 3-29.
Constantinesoo, I. Soil conservation for developing countries. Rome, FAO. 92 p. Soils
1976 Bulletin 30.
Costin, E. Forestry with special reference to sand dune fixation and establishment of
1972 windbreaks. The Agricultural Demonstration and Training Project at El-Kod
and Oiar, People's Democratic Republic of Yemen. Rome, FAO. 59 P ESR:
SF/SOY3, Research Series No. 5.
Dastane, N.O, Effective rainfall in irrigated agriculture. Rome, FAO. 62 p. Irrigation
1974 and Drainage Paper 25.
Delwaulle, J.C. Le role du forestier dans 1 ' am ftiagement du Sahel. Revue Bois et Forgts
1975 des Tropiques, no. 160: 3-22.
Doorenbos, J.. and Pruitt, W.O. Guidelines for predicting crop water requirements. Rome,
1977 (revised) FAO. 144 p. Irrigation and Drainage Paper 24.
FAO Salinity seminar, Baghdad. Rome, FAO. 254 P* Irrigation and Drainage Paper
1971a 7.
FAO Irrigation practice and water management. Rome, FAO. 84 p. Irrigation and
197lb Drainage Paper 1.
FAO Trickle irrigation. European Commission on Agriculture Working Party on
1973 Water Resources and Irrigation, Bucharest. Rome, FAO. 153 P Irrigation
and Drainage Paper 14.
FAO Report on the FAO/DANIDA inter-regional training centre on heathland and
1974 sand dune afforestation. Rome, FAO. 239 P* TOR: TF-INT 56 (DEN).
FAO Conservation in arid and semi-arid zones. Rome, FAO. 125 P FAO Conservation
1976 Ouide 3.
FAO Guidelines for watershed management. Rome, FAO. 293 p. FAO Conservation
1977 Ouide 1.
-117-
PAO/UNBSCO Irrigation, drainage and salinity, London, Hutohinson and Co., 510 p.
1973
Pirmin, R. Afforestation. Report to the Government of Kuwait. Rome, PAO. 69 p.
1971 FAO/KU/TF-46.
Pox, A.V. Afforestation of difficult sites, eroded areas and steep slopes, with special
1977 emphasis on the Nambilla Plateau (Nigeria). In Savanna afforestation in
Africa, pp. 181-189. Rome, PAO.
Oaussen, H. Theories et classification des climats et microclimats. Proceedings of the
1954 eighth International Botanical Congress, Paris, p. 125-130.
Ooor, A.Y, , and Barney, C.W, Forest tree planting in arid zones. New York, The Ronald
1976 Press Co., second edition, p. 504*
Gormaz, Q. , M. Las dunas, Santiago, Chile, Corporaci6n Nacional Porestal. 138 p.
1974
Qulcur, M. , and Nouri, A.K. Planning of irrigated tree plantation in Iraq. Forestry
1975 Research, Demonstration and Training, Iraq. Baghdad, FAO. 82 p. FOt
SP/IRQ 518, Working Document.
Heede, B.H. Ghilly development and control: the status of our knowledge. Port Collins,
1976 U.S.A., Rooky Mountain Forest and Range Experiment Station. 42 p. USDA
Forest Service Research Paper RM-169.
Heede, B.H. Gully control structures and systems. In Guidelines for watershed management,
1977 pp. 181-222. Rome, FAO. FAO Conservation Guide No. 1.
Horning, H.M. e al. General aspects of the planning and design of irrigation and drainage
1977 projects. In Mechanization of irrigated crop production, pp. 36-46. Rome,
FAO. FAO Agricultural Services Bulletin 28.
Iqbal Sheikh, M. Afforestation in waterlogged and saline areas. The Pakistan Journal of
1974 Forestry, April, 1974-
Iqbal Sheikh, M. , and Masrur, A. Drip irrigation - a new method of irrigation developed
1972 at Pakistan Forest Institute, Peshawar. The Pakistan Journal of Forestry,
October, 1972: 446-462.
Job ling, G.A. Trickle irrigation design manual. Lincoln College, New Zealand Agricultural
1974 Engineering Institute. Miscellaneous Publication nos. 6 and 7*
Kaul, R.N. (ed. ). Afforestation in arid zones. The Hague, Dr. W. Junk N.V.
1970
Khabe, W* Man-made forests on man-made ground. In Proceedings of FAO World Symposium on
1967 Man-Made Forests and their Industrial Importance, Vol. 2, pp. 1165-1176.
Rome, FAO.
Kunkle, S.H. f and Thames, J.L. Hydrologioal techniques for upstream conservation. Rome,
1976 FAO. 134 P* Conservation Guide 2.
le Rouz, P.J. Afforestation in low rainfall areas. South African Forestry Journal, no.
1975 93*
-118-
Libyan Ministry of Agriculture. Sand dunes: stabilisation and afforestation. Tripoli,
1973 Agricultural Brtension. 32 p. Bulletin no. 33.
Maomillen, E.H. Rationalisation of ploughing operations for drainage. Geneva, BCE/FAO/
1965 ILO. 27+ p. UN Publication 65.H.E/Mim. 14.
Mae son, J.L. Subsolaci&i. Unpublished report, Centro de Xnvestigaoiones y Capacitaoi6n
1973 Porestales, Cuba. 14 p.
Nikola, P. Special techniques for poorly drained sites, including peat bogs, swamps, etc.
1967 In Proceedings of FAD World Symposium on Man-Made Forests and their Industrial
Importance, Vol. 1, pp. 367-386. Rome, FAO.
Monjauze, M. Afforestation with the aid of heavy soil working implements. Indian Forester,
1960 86(7)1 388-394.
Netherlands State Agricultural University. Afforestation on eroded soils in Java
1973 (Indonesia). Wageningen, State Agricultural University. 58 p.
Penman, H.L. Natural evaporation from open water, bare soil and grass. Proceedings of the
1948 Royal Society, Series A, 193* 120-145.
Proceedings of A Symposium on Strip-Mine Reclamation. The Ohio Journal of Science, 64(2):
1964 65-175-
Research Committee on Coal Mine Spoil Re vegetation in Pennsylvania. A guide for re vegetating
1965 bituminous strip-mine spoils in Pennsylvania. 46 p.
(revised
1971)
Sacoardy, L. Notes sur le caoul des banquettes de restauration des sols. Torres et Eaux,
1950 11: 3-9-
Sacoardy, L* Njoessitf de la lutte centre lee Irosions: mthodes modernes de conservation
1959 des sals et des eauz. Bulletin Technique d f Information, 142 (July - Aug)i
411-419-
Saeed Khan, A. An appraisal of the existing water utilization practices in irrigated
1966 plantations. In Proceedings of the Second Pakistan Silviculture Conference,
pp. 149-158. Peshawar, Pakistan Forest Institute.
Seth, S.K. Methode steppique. Indian Forester, 86(7)1 385-387.
1960
Sheng, T.C. Protection of cultivated slopes - terrains steep slopes in humid regions, jh
1977 Guidelines for watershed management, pp. 147-179, Rome. PAD. PAD Conservation Quid
Siddiqui, K.M. Irrigated forest plantations in West Pakistan. In Proceedings of FAO World
1967 Symposium on Man-Made Forests and their Industrial Importance, Vol. 2, pp.
1121-1136. Rome, FAO.
Skoupf , J. Afforestation in the arid Mediterranean and Near East regions. Silvioultura
1976 Tropica et Subtropioa, 5t 3-19.
Stone, E.G., and floor, A.Y. Afforestation techniques for arid conditions. In Proceedings
1967 of FAO World Symposium on Man-Made Forests and their Industrial Importance,
Vol. 1 f pp. 345-3(6. Rome, FAD.
-119-
Terry T.A. t and Hughes, J.H. The effects of intensive management on planted loblolly pine
1975 (Pinus taeda L.) growth on poorly drained soils of the Atlantic ooaetal
plain. In Bernier, B. and Winget, C.H. (eds.), forest soils and forest land
manag<ement f pp. 351-377. Quebec Les Presses de I'Universite* Laval.
Thames, JL (ed. ). Reclamation and use of disturbed land in the Southwest. Tuoson y U.S.A.
The University of Arizona Press.
Thornthwaite , C.W. An approach toward a rational classification of climate. Geographical
1948 Review, 38(1)1 55-94-
Tsuriell, D.E. Sand dune stabilization in Israel. Rome, PAD. 21 p. FAO/DEN/TF 114.
1974
Ursic, S.J. Planting loblolly pine for erosion control in north Mississippi. New Orleans,
1963 U.S. A,, Southern Forest Experiment Station. 20 p. USDA Forest Service Research
Paper 30-3.
USDA Forest Service. Y-LT erosion control handbook. Atlanta, U.S.A., Southeastern Area
1974 State and Private Forestry. 55 P.
Weidelt, H.J. (compiler). Manual on reforestation and erosion control for the Philippines.
1976 Eschborn, Germany, F.R. , German Agency for Technical Cooperation. 569 p.
Wirabush, S.H. Afforestation of restored tin-mining land in Nigeria. Commonwealth Forestry
1963 Review, 42(3): 255-262.
Wood P.J. al. An irrigated plantation project in Abu Dhabi. Commonwealth Forestry
1975 Review, 54(2): 139-146.
-121-
CHAPTER 5
PROTECTION
All newly established plantations are liable to damage by weather conditions, by
insect t fungal or viral pests, by fire, by wild and domestic animals and by man. The
degree of risk from any of these causes will vary with the environmental conditions of
each plantation and should be assessed during the planning stages, so that prevent at ive
measures can be taken or at least anticipated during establishment.
In theory remedial measures can be devised to guard against most forms of likely
damage, except perhaps tornados or hail storms and other extreme weather phenomena for
which insurance brokers use the term "Acts of God". Forests and plantations, because of
the cover and shelter they provide, may sometimes suffer from indiscriminate acts of war,
but for all predictable risks, the main problem facing the forester is one of assessing the
cost/risk/benefit ratios. Total protection against all risks, or against one or more of
the more probable risks, mi^rt well prove so costly that no final commercial benefit would
result from the planting investment. In such cases a decision must be taken either to
abandon the project or to compromise by accepting some degree of risk, thereby reducing
the costs of protective measures to a more acceptable level. Not all risks can be readily
forecast or assessed, and this is particularly the case where exotics are being planted in
new environments where native insects or fungi may adapt to the new hosts. On the other
hand, the probability of other types of damage can often be more realistically evaluated
and the cost/effectiveness ratios of remedial or protective measures can be assessed.
Some of the main risks of damage and the measures available to secure protection
are discussed under weather, insect or fungal pests, animals, including man, and fire
protection as follows.
WEATHER CONDITIONS
The frequency of damaging phenomena such as cyclones, tornados, hail storms, drying
or salt-laden winds, severe frosts, heavy snowfall and avalanches are usually predictable,
though foresters can do little to protect plantations against the damage caused by them f
except by growing tree species known to be resistant or by siting the stands in sheltered
localities* Some species are more windfirm than others, or are less prone to damage from
crowns and branches breaking off in high winds* Other species are more tolerant of salt
pray and can be used for planting in belts along exposed seaward flanks to give protection
-122-
to other leas tolerant species forming the main plantation. Thin barked species are more
liable to that damage (and to subsequent attacks of insect or fungal pests) than others.
In South Africa the planting of Pinus radiata and P. patula in many parts of the country
has had to be abandoned on account of severe attacks of the fungus Diplodia pinea associa-
ted with hail damage. Pinus elliottii and P. palustris t which are largely resistant to
Diplodia attack, are being planted instead."" Frost can sometimes cause severe damage even
to species known to be frost hardy in their native habitats. Late or unseasonal frosts
occurring outside the dormancy period can result in severe setback to young trees by killing
the new and tender growing shoot buds or tips. Remedies lie in selecting late shooting
species or provenances; Picea sitchensis, for example, is generally more frost hardy than
P. abies, and some species and provenances of eucalypts are more resistant to frost than
others. Some protection may also be given to susceptible trees by planting them in mixed
stands together with frost-resistant species. In regions of heavy snowfall, it is neces-
sary to select species which are less susceptible to breakage under the weight of heavy
snow.
IN3BCT AND HJNQAL PESTS
Most insect and fungal pests are selective of the host species. In their native
environment , trees whether in natural or man-made forests, normally attain a state of
equilibrium with indigenous pests. When exotic trees are planted, these pests may be
introduced and sometimes develop greatly enhanced virulence in the conditions of their new
habitat. Well known examples of this are the chestnut blight (Endothia parasitica), a
native of Asia, which caused havoc among chestnut plantations in Europe and North America,
and the Dutch elm disease (Ceratocystis ulmi) which also spread to Europe and America from
Asia, where most native Ulmus species are resistant to the disease. Sometimes exotic
species may be attacked by local pests which adapt to new introductions. In New Zealand a
native defoliating insect (Selidosema suavis) has become a serious pest in Pinus radiata
plantations. The Cypress canker (Monochaetia unicornis) in East Africa is an unimportant
disease on the native Juniperus procera. but has become, possibly by a change in strain,
epidemic in the extensive plantations of introduced Gupressus macrocarpa. As a consequence
this species is no longer planted and is being replaced by the more resistant . lusitanica.
The risk of damage from pests and diseases is generally higher if the trees are
physiologically weakened, for example from inefficient planting or site preparation, from
being planted on unsuitable sites or in adverse climatic conditions or from neglect of
weeding and tending operations. But even healthy trees are sometimes attacked. For many
important fungal and viral tree diseases no control is yet available, and the best precauh-
tion is to plant species or varieties known to be resistant to the disease.
The main precautions to be taken, therefore, in guarding against possible future
damage from pests and diseases are to see that the species selected for planting are suit-
able tothe climatic and soil factors of the site, andto make surveys of indigenous pests, to
ensure that none of these is among the known forms to which the selected species is suscep-
tible. This is seldom easy, especially in view of the gaps in available knowledge on site
requirements and disease susceptibilities of many of the more important exotic species; the
more reason, therefore, for initiating carefully controlled experiments and plot plantations
before developing large-scale afforestation work.
Care taken in the establishment and tending operations during the early years of a
plantation, resulting in healthy vigorous young trees, makes a plantation more resistant
to pests and diseases. However, if symptoms or evidence of attack appear, these should be
promptly investigated and the cause identified. Various control measures are available:
these may be si Ivi cultural, chemical, biological or mechanical.
-123-
Silvioultural Control
Silvicultural measures include well-timed and careful thinnings, mainly after the
establishment phase has ended. These help to resist attacks "by eliminating poor and
suppressed stems, thereby maintaining the plantation in a thrifty and vigorous growing
condition. In young plant at ions, the prompt removal and destruction of infested trees may
be effective in preventing the spread of the attack to the rest of the plantation. Plant-
ing of mixed species can also be considered a silvicultural control method where the threat
of infection is known to exist. The disadvantages of mixed planting within a compartment
or plantation unit, giving rise to complications in later management, can be avoided by
planting alternate blocks or wide belts with different species or genera, such as conifers
and hardwoods, to form barriers to the spread of a disease from some initial point of
infection.
Chemical Control
Insect and fungal pests can also be checked by applications of an appropriate
chemical insecticide or fungicide. These are usually available in liquid (or wettable
powder) formulations, as dusts or as smokes. Spraying with hand-operated knapsack spray
guns or portable mist-blowers is used to control attacks in very young plantations, but
after canopy closure, aerial spraying and dusting or smoking is usually cheaper and more
effective.
Dieldrin and aldrin have been successfully used against termite attack in tropical
eucalypt plantations. A small dressing of insecticide is either mixed into the nursery
potting soil or mixed with water as a suspension and watered on. Insecticides have also
been effective when applied to the soil around the plants at the time of planting.
In South America leaf-cutting ants, usually of the genus Atta or Acromyrmex are the
chief pests of forest plantations. These can be controlled prior to planting and during
the establishment phase by fumigating the nests with methyl-bromide (sometimes mixed with
chloropicrin to produce a detectable odor) or by treating the nests or ant trails with
mirex or other chemicals. Treated "baits which are carried underground into the nests by
the ants are particularly effective.
Dothistroma on Pin us radiata in New Zealand has been kept under control by copper-
based sprays (Gilmour and Noorderhaven, 1973); and a brown needle disease, probably
Gercospora pini-densiflorae, seriously affecting P. caribaea seedlings in Malaysia was
controlled "by nursery applications of the fungicides benlate, topsin M, daoonil or difola-
tan 4P (Ivory, 1975).
The insecticides and fungicides most commonly used are noted in tables 3 and 4
Biological Control
Biological control of insects has been used with success in certain cases, usually
after the pest has grown to epidemic proportions. In southern and eastern Africa, for
example, a Mymarid egg parasite imported from Australia has proved to be an effective agent
of control against the Eucalyptus snout beetle, Gonipterus scutellatus t a major defoliator
of Eucalyptus spp. (Browne, 1968).
Mechanical Control
Mechanical control can be effected either by physically removing and destroying the
pests or "by eliminating an alternate host. Some fungal diseases, for example, have alter-
nate hosts. The best known example is white pine blister rust (Gronartium ribicola) on
Pinus strobus and other 5-needle pines, the alternate host being species of Ribes. The
control method in such cases is to eliminate the alternate host plant by cutting or by
using herbicides within the plantation area and for a zone (at least 3 kilometres wide)
around the periphery.
-124-
In Tunisia the Eucalyptus longhorn beetle, Phoracantha semipunctata was brought
under control by the use of trap trees. Prom ten to fifty trap trees per hectare are
used f depending on the severity of infestation. The trap trees are cut and, after
slicing the bark with a machete, they are leaned into the crowns of the remaining trees.
After a few weeks, the trap trees are extracted and their bark, with beetles, is removed
and burned. The wood can be utilized. Sexual attract ants can also be used to draw the
insects to the trap trees.
In the case of undesirable insects which pupate in the leaf litter or top soil,
raking up the litter and burning helps to reduce the incidence of the attack. Pigs rooting
in the litter in pine plantations have been found beneficial in South Africa. In South
America, leaf-cutting ants are sometimes burned out by soaking their nests with kerosene
and igniting. Chemical control is preferred, however.
Table 3s Useful Insecticides
Pest
Chemical Control
Aphids
Beetles
Capsids
Caterpillars
Leaf-cutting ants
Leaf hoppers and miners
Mites and red spiders
Sawflies
Soil pests (termites,
chafer-grubs, cut -worms,
etc.)
Weevils
DDT, Demethon-methyl*, Diazimon, Dimethoate*,
Malathion, Menazon*, Mevinphos*, Nicotine,
Oxydemet on-met hyl, Parathion, Phosphamidon*,
Schradan*, BHC (or DDT with BHC), Endrin,
Mecarbam.
BHC, DDT, BHC with Thiram, Derris, Malathion.
DNOC in Petroleum oil (only for hardwoods in
dormant stage), BHC, DDT, Diazinon, Nicotine.
DDT, Derris, Mevinphos*, DNOC in Petroleum oil,
Lead arsenate, "Rhothane 11 , Carbaryl, Endrin.
Mirex, Aldrin, Dieldrin, Heptachlor, Chlordane,
HCH, Lindane.
BHC, DDT, Malathion, Diazinon, Nicotine,
Parathion.
Demeton-methyl*, Oxydemet on-methyl* , Schradan*,
Tetradifon, Azinphos-methyl, Chlorbenside,
Chlorfenson, Dimethoate*, Ethion, "Kelthane",
Malathion, Phosphamidon*.
HHC, BHC with DDT, Endrin, Fho spheroid on*.
Aldrin, Dieldrin, HHC, DDT, Lead arsenate.
DDT, Aldrin, Dieldrin, Rhothane.
* These are systemic insecticides (that is, absorbed and distributed
in the plant iap).
-125-
Table 4: Useful Fungicides
Diseases Chemical Control
Damping off fungi in nurseries, needle Bordeaux spray, Captan Orthicide
"blight (Scirrhiza acicola). blister rusts
(Cronartium comptoniae).
Southern cone rust (Cronartium strobolinum) . Perbam
Cedar bli^rb (Fhomopsis juniperovora) Phenyl-mercuri-triethanol-ammonium-
lactate
Mildews, scab, Dothichiza sp. Lime sulphur
Needle bli^it (Pothistroma pini), needle Copper fungicides
cast (Lophodermium pinastrij^
Root fungi (Pomes annosua. Armillaria me lie a) Creosote (painted on cut stumps)
ANIMAL DAMAGE
Damage by Wild Animals
Damage to forests by wild animals mainly takes the form of tree browsing or of
barking. There are three main orders of wild animals responsible for damage:
- rodents (rats, mice, moles, squirrels, chipmunks, and porcupines);
- lagomophs (hares and rabbits);
- artiodactyls (deer, antelopes, pigs and buffaloes).
In specific geographical regions, serious damage is also caused by proboscides
(elephants in Africa and southern Asia), marsupials (oppossums in Australasia and the
Americas) and primates (monkeys in Africa, Asia and South America). Seed-eating birds are
also a frequent cause of difficulty, particularly where forests are established by direct
seeding.
The principal methods of controlling wild animal damage are by use of (l) fences,
hedges and ditches; (2) poison baits; or (3) by shooting and trapping.
Pence a, Hedges and Ditches
The construction of barriers, such as post and wire fences or impenetrable live
hedges (thorn bushes, cactus, etc.) are the most effective means of preventing the ingress
of most wild animals, except the climbing types, the very small ones (rats and voles, etc.)
and the very large animals (elephants, buffaloes).
Fencing is easy to erect at the time of establishment but is generally expensive.
Where alternative means of protection are not feasible, the cost of fencing has to be
accepted.
The type of fencing used varies with the type of animal to be excluded and the
materials available. The standard fence for deer is 2 m in heigjrt, made of six strands of
barbed wire strained on angle-iron or wooden posts at intervals of 3 to 4 m. In Europe, a
long-lasting deer fence using metal posts is expensive, but fences using wire mesh and
creosoted wooden posts cost much less. Where rabbits and hares are the main source of
trouble, fine meshed (107 x 3 cm) wire netting is necessary along the lower part of the
fnoe. In the U.K., it is also standard practice to bury the bottom (15 cm) of netting in
the ground to prevent rabbits burrowing under the fence. Electric fencing has been used to
exclude wild animals and domestic stock, but in general has not proved satisfactory. In
very dry climates, they are ineffective unless fitted with an earth return wire.
-126-
Post and rail fences are sometime* used where wire is too costly or too difficult
to obtain and where ligfit poles are plentiful. In Kenya, a form of post and log fence has
proved effective against most game for taungya plantations. It consists of pairs of posts
1 m apart at 2 m intervals with the interstices filled with logs or wood cleared from the
planted area. In the African Sahelian zone, fences are sometimes constructed as staked
barriers of thorny or spiny branches.
For the exclusion of elephants and other species of big game, moats (2 by 1 .5 m
ditches covered with brushwood) have been found to provide a most effective barrier in Kenya.
Hedges or barriers of closely planted bushes or trees, often of spine-bearing species,
planted round the periphery are used in many countries to exclude game or, more often, do-
mestic grazing animals. In Kenya, trial plantings of eucalypts spaced 1 m apart around coni-
fer plantations are reported as having satisfactorily excluded very big game.
Hedges have many limitations in their usefulness:
1) They must be established several years ahead of the planting work and
this is often inconvenient or not possible;
They need frequent tending, trimming and shaping to maintain their effectiveness;
They are not effective against small animals;
They are subject to damage by browsing, bark stripping and fire;
They take up more space than fences and
They hinder transport.
Poison Baits
Smaller mammals such as rodents and lagomorphs are mainly controlled by the use of
poison, distributed either in bait or applied directly to ground vegetation or tree seeds.
Most poisonous chemicals are of the "contact" variety, which are effective only as long as
they remain on the surface of the trees or seeds, but research is currently being under-
taken into the use of systemic poisons which are absorbed and translocated by the plant
and provide protection for considerably longer periods.
Strychnine, zinc phosphide, sodium arsenite, warfarin, "1080" and thallous sulphate
are examples of the many different poisons distributed in bait. In Australia a general
method used for controlling rabbits is the distribution from the air of chopped carrots
treated with "1080".
Endrin/aldrin emulsions and toxaphene (chlorinated camphene) have been sprayed on
vegetation or young trees as a repellent.
Various poisons have been applied to tree seeds to reduce damage from rodents and
birds. Endrin, a non-phytotoxic formulation containing thiram (tetra-methyl-thiuram-
disulphide) has been used most commonly especially with coniferous seeds. Endrin has
recently found a wider application on tree seed in sub-lethal doses as a repellent.
Colonial animals which live in burrows can be controlled by fumigation or gassing
with chloropicrin, phosphine, carbon monoxide or cyanide. A new fumigating, which is being tried
extensively in Victoria and Western Australia, consists of carbon monoxide combined with a
foaming agent, which is forced into the warren killing the rabbits and coating the burrows
with a residual repellent slime.
The main limitations affecting the use of chemical poisons are their toxioity to
the people handling them and to non-offending animals and the prohibitions relating to
their use imposed by law in many countries.
Shooting and Trapping
Shooting and trapping is also used to control wild animals, often in combination
with fencing and poisons. Where the wild animals have value as food or as trophies, con-
trol by hunting can often be organised through volunteer hunters without cost (emetines
even with financial gain) to the plantation project.
Trespass by Domes-bio Animals
In some countries grazing or browsing by flocks of sheep and goats, herds of cattle
and more rarely of equines can constitute a major menace to young plantations*
Hedges and fences are commonly used to prevent trespass of domestic animals. In
other circumstances, particularly where fencing costs are prohibitively hi#i, trespass can
be controlled by guards, and by taking legal action against the owners of straying animals.
The impoundment and confiscation of such animals may occasionally prove an effective
deterrent.
In many regions, especially in dry areas, free-range grazing by goats is tradition-
al in degraded, eroding grazing lands. Extensive enclosures for forestry can mean the
imposition of drastic changes in the habits and economies of the communities affected. In
such circumstances it would be unwise to commence afforestation unless alternative means
of livelihood, compensating the communities for restrictions in their traditional use of
the land, had been provided beforehand. This generally implies the initiation of integra-
ted community development schemes including improved agriculture and husbandry, better
communications, schools and medical welfare, increased opport unities for employment by the
development of rural industries, including afforestation and rural forest industries. In
some cases, such development may involve providing inducements for localized emigration to
new industrial centres, as occurred in southern Yugoslavia following the outlawing of all
free-range goat grazing in the nineteen fifties.
Trespass by Man
This can take many forms - encroachment cultivation, the diversion of water sources,
the taking of wood and other forms of forest produce, unlawful hunting and fishing and
other recreative uses of a forest. In general, the risk of damage by human trespass is not
serious in the case of newly-established plantations except inasmuch as it increases the
fire hazard. Where such forms of trespass constitute a hazard or are likely to develop
subsequently as a source of trouble, it is part of good planning to make allowance for such
community needs from the beginning of the plantation work. This may mean reserving certain
areas of the plantation for the production of fuelwood, poles and other produce in demand
by the local communities, by providing authorized hunting and fishing facilities, or by
channelling people seeking recreation to specifically reserved forest amenity areas, pro-
vided with picnic sites, camping grounds and forest accommodation.
FIRE PROTECTION
The Fire Hazard
Damage by fire imposes a serious threat to plantations in most countries. The fire
hazard increases, of course, in the dryer climatic regions, but even in relatively moist
or high rainfall areas, there are often warm and dry spells when the fire risk is higjh. In
many parts of the world, annual or periodic burning of vegetation is common practice, and
establishing plantations in such areas requires that fire-risk should be a major considera-
tion from the early stages of development.
Fires may originate from natural causes such as lightning, but most occur as a
result of the activities of man. Plantation fires may start from camp or picnic fires,
from fires spreading from farmland on the perimeter of the forest, from the activities of
hunters or from burning by sheperds or herdsmen to improve grazing. There have even been
recorded cases of deliberate firing to create employment in suppression and replanting or to
show disapproval of forest policies. As forest contractors are also often careless in
their attitude to fire, it would be advisable to include some fire protection requirements
in contract agreements. It is not possible to prevent a climatic build up of high fire
hazard conditions, but much can be done to minimize the risk of fire by public education,
by involving local people in forestry and by persuing policies sympathetic to the political,
social and economic needs of the community.
-128-
Where planted crops are either not weeded or are partially weeded, they are par-
ticularly vulnerable to fire during the establishment phase. Where plantations are clean
weeded, however, there is no fire risk. By cultivating the soil there is no combustible
material at ground level and the entire planted area including individual trees are pro-
tected. Once a plantation crop closes canopy, if the canopy is sufficiently dense to
exclude grass and other weeds, then the risk of fire remains low. If, however, the
plantation crop is light crowned, allowing a fairly dense ground cover of weeds, then the
fire hazard is higfr.
The main principle in protecting plantations against fire is that where there is
insufficient combustible material to allow a ground fire to develop there is little or no
fire risk. Dangerous and damaging plantation fires can only develop when fire can occur
at ground level.
Fire Prevention and Hazard Reduction
The layout of a plantation is influenced by a number of factors already noted but
fire control is one of the main considerations, which not only influences road and fire-
break alignment but also the dimensions of compartments and blocks, amongst other items.
A plantation requires both a "fire plan" and a fire control section. One of the primary
requirements of such a plan would be to provide training in control and fire-fighting. A
trained fire control section would be responsible for controlled burning, maintenance of
firebreaks, assessment of fire hazard, maintenance of fire towers, fire reporting and
initial fire suppression. Fire may start outside the plantation and carry in or may
start inside and spread. Consequently fire control operations should be designed to pre-
vent fires from both these sources.
Firebreaks
The purpose of a firebreak is to provide access through the plantations and to
provide a fuel-free barrier to fire. Firebreaks are generally oriented at right angles to
the direction of the prevailing wind during the dry season. A road in itself may consti-
tute a firebreak. A road may be supplemented by a narrow ploughed strip to form a composite
firebreak. Firebreaks maintained by ploughing are sometimes ineffective if heavy grass
cover is only partially removed during cultivation, and of course such cultivation adds to
costs. Wide, cultivated firebreaks give every appearance of effectiveness, but can seldom
be wide enou^i to prevent spot fires crossing from a hi^i intensity fire. In addition to
being costly to establish and maintain, they channel wind flow along the break and cause
turbulence at the plantation edges.
Green firebreaks planted to suitable, usually evergreen species are a further
possibility. The main requirement of a green firebreak is complete canopy closure and a
clean forest floor maintained free of litter by periodic burning. When controlled burning
is practised, green firebreaks become largely redundant as they receive the same treatment
as the plantation.
With the limitations of the various types of firebreaks, the trend is towards an
intensive internal network of narrow clear roads (at least 1 m of right-of-way) which serve
as access and as firebreaks within blocks. At the same time, perimeter road/firebreaks are
maintained, where there is a risk of fire from outside the plantation. To prevent fire
entering a plantation from the surrounding areas, controlled boundary burning is often
practised.
-129-
B.' ' /
Although the tendency is toward narrow firebreaks, wide breaks are still used.
^ Pinus patula plantations on the Viphya Plateau in Malawi f firebreaks about
200 m wide are preferred. Where possible, these are sited to take advantage
of natural terrain features such as rooky ridge outcrops. The firebreaks are
burned annually to reduce fuel buildup; in addition a strip about 2 ra wide is
cultivated around the entire plantation perimeter to guard against the entry of
low ground fires. (Courtesy D.A. Haroharik)
Control Burning
Control burning is effected within the plantation in such a way as to cause no
damage to the standing crop. It is, therefore, restricted to thick barked species and is
seldom possible until the tree crowns are well above reach of the ground fire (i.e after
canopy closure) The timing of the first control burn in a young plantation is critical;
for pines a mean height of between 8 to 11 m covers a range of likely suitable conditions,
but this will vary with local conditions.
Where the fuel layer is heavy, burning should not aim at complete removal in one
operation, as the conditions suited to a single burn could cause too intense a fire with
inevitable damage to the trees. Heavy fuels can, however, be removed by several successive
burns over the same area - removing a proportion of the fuel bed on each occasion.
Control burning is carried out under accurately defined weather conditions which
should allow a prescribed pattern of fire behaviour to be achieved. It is best done late
in the wet season, or early in the dry season, and at night, or at least after the hottest
part of the day* As experience is accumulated it should be possible, for a given set of
conditions, to estimate a period during whioh control burning will be effective.
-130-
The following general prescriptions are valid tor moat conditional (Cheyney, 1971):
1) Conduct test fires to determine first the rate of spread of fire and
second at what time fires mi#it be Belf-ertinguiahing} these should
be carried out in advance of the main burning operations.
2) If the forward spread of burning exceeds 60 cm per minute, burning
should not be carried out.
3) Burning should only take place when wind conditions are calm or less
than 8 km/hr.
4) There should be no burning if the relative humidity drops below 35$
during the day.
5) Burning should commence in the afternoon or later when the relative
humidity rises above
6) If tall grass is present in the plantation, burning should occur
before these annual grasses have become fully dried.
Fire Detection, Assessment and Supression
Fire Detection
A sound fire detection system is usually based on fire towers. These towers should
be sited to give maximum coverage of the plantation and environs and should allow ready
triangulation so that accurate cross bearings can be recorded. Each tower should be equip-
ped with an alidade, binoculars and a radio/telephone. The system should be established
early in the plantation development.
Fire Danger Assessment
Where there is a higfr fire hazard, the setting up of a fire danger rating system is
recommended. Such a system which relates the four major meteorological factors affecting
fire behaviour - temperature, relative humidity, wind speed and long and short term drought
effects - may be readily calculated for most conditions.
Pire Supression Techniques
The first essential in fire fighting is that there should be adequate transport to
carry personnel to the site of fires as quickly as possible. If dealt with quickly, many
fires can be readily extinguished by hand. A suitable range of equipment for a gang isj
- knapsack sprayers - hoes (long handled with large blades)
- shovels - light, strong pointed - electric torches (for night operations)
- axes (preferably 4 Ib) - drinking water supplies
- maohettes - first aid kits
Other items are the rake/hoe or McLeod Tool from Australia and back firing drip torches.
There is a considerable range of mechanized equipment for fire control - pumps,
tankers and tractor units - which may be required under certain conditions. Par effective
use of much of the pumping equipment, there have to be suitable water supplies within easy
range of the plantation area. Where water supplies are inadequate or too distant, recourse
has to be made using fire figjrting methods not requiring large volumes of water*
-131-
No two fires are likely to behave in the same way, but the following are general
fire fighting techniques which migjrb be employed in particular situations:
1) The first point of attack should be the head of the fire f followed
by the windward flank.
2) Pirelines parallel to the edge of the fire may be formed by:
a,}
b)
raking or hoeing to mineral soil and;
by pushing material directly into the fire.
3) Back burning can be very effective but requires experienced orews.
It should only be attempted from less than 100 m directly in front of
the head fire.
4) Where water is scarce, it must be used efficiently; it is of particular
importance in mopping^-up.
5) Mop-up is the extinguishing of all burning and smouldering material
within 20 m inside the fire control line. It is essential to continue
mop-up and patrol until a fire is completely extinguished. Many
apparently dead fires have restarted after being abandoned too soon.
It is essential to train staff and labour in fire fitting techniques. Training
exercises should be held periodically, but too frequent training may reduce rather than
increase interest and efficiency.
BIBLIOGRAffiY AND REFERENCES
Bakshi, B.K. Diseases of man-made forests. In Proceedings of PAO World Symposium on
1967 Man-Made Forests and their Industrial Importance, Vol. 1, pp. 639-661.
Rome, FAO.
Boyce, J.S. Forest plantation protection against diseases and insect pests. Rome, FAO.
1954 41 p. FAO Forestry Development Paper No. 3.
Boyce, J.S. Forest pathology. New York, McGraw-Hill Book Co. f *572 p.
1961
British Forestry Commission. Principal butt rots of conifers. London, Her Majesty's
1965 Stationery Office. Forestry Commission Booklet No. 13.
British Forestry Commission. Forest fencing. London, Her Majesty's Stationery Office.
1972 Forest Record No. 80.
Browne, F.G. Pests and diseases of forest plantation trees. Oxford, Clarendon Press.
1968 1330 p.
Brtinig, E.F. Protection against inorganic damage - types of damage other than fire. In
1967 Proceedings of FAO World Symposium on Man-Made Forests and their Industrial
Importance, Vol. 1 f pp. 757-772. Rome, FAO.
Cheney, N.P. Fire protection of industrial plantations. Forest industries feasibility
1971 study, Zambia. Home, FAO. Technical Report 4.
-132-
Czabator, F.J. Fusiforn rust of southern pines - a critical review. New Orleans, U.S.A.,
1971 Southern Forest Experiment Station. 39 P USDA Forest Service Research
Paper 50-65.
FAO. Proceedings of FAO/IUFRO Symposium on Internationally Dangerous Forest
1964 Diseases and Insects. Rome, FAO. 2 vols.
FAO. Proceedings of Second FAO World Technical Consultation on Forest Diseases
in press and Insects. New Delhi, India.
Fettes, J.J. & Buckner, C.H. Biocides in the forest - use and misuse. Paper for Seventh
1972 World Forestry Congress, Buenos Aires. 8 p.
Gibson, I. A. Diseases of forest trees widely planted as exotics in the tropics and
1975 southern hemisphere. Part I: important members of the Myrtaceae,
Leguminosae, Verbenaceae and Meliaceae. Kew, U.K., Commonwealth Mycolo-
gical Institute. 5^ P
Qilmour, J.W. & Noorderhaven, A. Control of Dothistroma needle "blight by low volume aerial
1973 application of copper fungicides. New Zealand Journal of Forestry Science,
3(1): 120-136.
Gooding, C.D. Rabbit fumigation. Western Australia, Department of Agriculture. Bulletin
1963 No. 3096.
Gray, B. Economic tropical forest entomology. Annual Reveiw of Entomology,
1972 Vol. 17: 313-354.
Greig, B.J.W. & McNabb, H.S., Jr. Management of Pomes annosus root rot disease in pine
1976 crops in Britain. Iowa State Journal of Research, 50(3): 287-292.
Hancock, M.J.D. Control del fuego en el e stab lee indent o y mantenimient o de bosques de
1973 Pinus caribaea. Investigation sobre el Foment o de la ProduccioVi de los
Bosques del Noreste de Nicaragua. Rome, FAO. 113 p. FO:SF/NIC 9,
Informe TScnico 4.
Heidmann, L.J. Frost heaving of tree seedlings: a literature review of causes and
1976 possible control. Fort Collins, U.S.A., Rocky Mountain Forest and Range
Experiment Station. 10 p. USDA Forest Service General Technical Report
RM-21.
Hepting, G.H. Diseases of forest and shade trees of the United States. Washington, D.C.,
1971 U.S. Government Pointing Office. 658 p. Agriculture Handbook 386.
Hochmut, R. & Milan Manso, D. Proteccifa contra las plagas forestales en Cuba. Habana,
1975 Institute Cubano del Libro. 290 p.
Holloway, C.W. The protection of man-made forests from wildlife. In Proceedings of FAO
1967 World Symposium on Man-Made Forests and their Industrial Importance,
Vol. 1, pp. 697-715. Rome, FAO.
IUTOO. Diseases of widely planted forest trees. Washington, D.C., U.S. Government
1964 Printing Office. 237 P.
Ivory, M.H. The pathology of Pinua spp. in West Africa. The Commonwealth Forestry
1975 Review, 54(2), No. 160i 154-165.
Kimball, B.C. Fire control. Demonstration and Training in Forest, Forest Range and
1971 Watershed Management, the Philippines. Rome, FAO. 62 p. FO: SF/ffil 16,
Technical Report 10.
-133-
McArthur, A.G. Fire protection of man-made forests. In Proceedings of FAO World
1967 Symposium on Man-Made Forests and their Industrial Importance, Vol. 1 f
pp. 717-745. Rome, FAO.
Mobley, H.E. et al. A guide to prescribed fire in southern forests. Atlanta, Georgia,
1973 U.S. A., USDA Forest Service, State and Private Forestry. 40 p.
Nordin, V.J. Biological control of forest diseases. Ottawa, Canadian Forestry Service.
1972 65 p.
Pawsey, R.Q. & Rahman, M.A. Chemical control of infection by honey fungus, Armillarja
1976 mellea; a review. The Arb or i cultural Journal, 2(8).
Roberts, R.B. (ed.). Pesticide spray applications, behaviour, and assessment: workshop
1973 proceedings. Berkeley, U.S.A., Pacific Southwest Forest and Range
Experiment Station. 68 p. USDA Forest Service General Technical Report
PSVM5.
Roth, E.R. Resistance: a literature review of important insects and diseases.
1970 Atlanta, U.S.A., USDA Forest Service. 59 p.
Show, S.B. & Clarke, B. Elements of forest fire control. Rome, FAO. 110 p. FAO Forestry
1953 and Forest Products Studies No. 5.
Smalley, E.B. Results in practice - forestry. Chapter II, Part V of Systemic fungicides,
1977 R.W. Marsh (ed.), pp. 294-319. London, Longman.
Torrent, J. & Romanyk, N. Proteccion contra plagas. In Proceedings of FAO World Sympo-
1967 sium on Man-Made Forests and their Industrial Importance, Vol. 1,
pp. 663-696. Rome, FAO.
USDA Forest Service. Prescribed Burning Symposium Proceedings. Asheville, U.S.A.,
1971 Southeastern Forest Experiment Station. 160 p.
Wilson, C.C. Protecting conifer plantations against fire in the Mediterranean Region.
1977 Paper for the FAO/Unesco Technical Consultation on Forest Fires in the
Mediterranean Region. Rome, FAO. 29 p.
-135-
CHAPTER 6
PLANTATION PLANNING
INTRODUCTION
Planning can be done at several different levels. A simple example of the type of
objective to be achieved at different levels of planning might be:
Level
1. National forest policy or
national forest objective
2. National quantitative forestry
target
3. Project aim
4. Operational planning
Execution or management
Example
Make the country self-sufficient in wood
by 2010 A.D.
Produce X million m of pulpwood annually
in 2010 A.D. and an additional 5$ annually
thereafter.
Plant 2 000 ha of Pin us patula and 500 ha
of Eucalyptus grand IB annually in district
A f for production of Y nn of long fibre
and Z m3 of short fibre pulp on rotations
of 20 and 10 years respectively.
Arrange beforehand how and when to obtain
seed f prepare nurseries, carry out site
preparation etc. f in order to achieve the
project aim as efficiently as possible.
Convert operational plans into effective
action.
A previous publication (PAO f 1974) reviewed the principal features of development
planning and explored how to identify the appropriate role of the forestry sector in
national planning, how to define this in terms of sectoral objectives, how to translate
these into quantitative goals and targets and how to identify and appraise projects within
this framework. It did not cover operational planning - the balancing of work and resources
in the short term and the completion of programmes of work within a timetable. Another
-136-
document (Fraser, 1973) , dealing with the planning of man-made forests, included a chapter
on operational planning, but was mainly concerned with the phases of project specification,
collection of data and project appraisal.
The present chapter is concerned solely with the operational planning of forest
plantations - plantation management planning. This type of planning assumes the existence
of clear directives which give little freedom of choice to the project manager as to what
he does but some degree of freedom as to how he does it*
Although the scope of the chapter is deliberately limited to plantation management
planning, it is necessary to stress the close relationship between the different levels or
phases of planning. The methods worked out to achieve an objective at one level of plan-
ning often become the objective at the next lower level. Later experience will bring about
an interaction between several planning levels. For example, experience gained in execu-
ting an operational plan may indicate how it should be improved, while project aims may be
modified periodically to conform with changing national needs. As has been often stated,
planning is an iterative process.
PLANTATION MANAGEMENT PLANNING
Project operational planning provides a programme of action designed to fulfil the
aims of the project. It prescribes what work will be done, where, how and within what
timescale. Because of the long-term nature of forestry, it is essential that the outcome
of planning forest plantations be expressed in the form of a written plantation management
plan.
The manager of a forest plantation project is likely to be concerned with three
levels of project planning:
1. A skeleton plan for long-term management of the project, which may cover a full
rotation or more. Prepared during the phase of project identification/appraisal,
it provides a framework in which the project manager is expected to prepare a
more detailed management plan during the phase of operational planning.
2. The plantation management plan, covering a medium-term period and providing
background information and management prescriptions.
3. An annual programme of work, indicating the work to be done, the resources
needed to do it, and when it is to be done. This can usually be prepared on
standard forms, with a monthly or weekly breakdown.
COLLATION OF DATA FOR THE PLANTATION MANAGEMENT PLAN
The collection of relevant data is fundamental to all phases of planning, and the
quantity and detail of additional data required in the operational phase will depend to a
great extent on the quality of data collected in the previous phases. In some cases, where
the project identification and appraisal phases have been both expeditious and efficient,
very little additional data may be necessary. The data required for a plantation manage-
ment plan include resource, operational and institutional data, for use in both the des-
criptive and the prescriptive parts of the plan. Much of the technical and cost data will
be derived from past plantation work, from pilot plantations or from trials. Operational
data will be derived from records of past work either in the project area or from compar-
able conditions outside. Where adequate data have not already been compiled, surveys may
be necessary. Very often data such as costs are not readily available and it is necessary
to use estimates, while clearly stressing the need to make good the deficiencies by sub-
sequent collection of the necessary data.
-137-
Resources Data
The main resources to be considered are land, planting stock, materials and equip-
ment, human and financial resources. The required information on these is availability,
productivity and cost.
Land Resources
The first essential is sufficient plantable land to accommodate the project
planting programme; indeed, excess land is desirable to allow for unforeseen problems and
possible future expansion. Where tribal or other legal rights affect the long-term use
or availability of land, such matters require determination and clarification before
further planning is undertaken.
In the early stages of development it is not possible to assign site quality
classes to soil types, but a simple plantability classification can indicate the better
areas for planting. The assessment of plantability requires a soil survey and the prepa-
ration of maps showing soil types, forest capability and vegetation types. At the same
time as the vegetation is recorded the tree cover is sampled for basal area to give a
measure of tree density, a major factor in land clearing.
Established growth trials of plantation species should be available to indicate
the productivity for the range of plantable sites. There is some merit in planning to
plant the better sites first while research and growth trials produce further data on
secondary or marginal sites. Where forest reserve land is available, there are no direct
costs for the resources but, where land is acquired by purchase or compensation, such
costs are recorded and debited. The annual requirements for planting land should be
allocated on a map of plantable land.
Planting Stock Resources
The primary requirement is an adequate and sustained supply of seed of the selec-
ted species and provenances. Selection of species is a major subject but it is assumed
that species and provenance trials will have been extensively evaluated prior to the
preparation of the plantation management plan. Seed supplies often prove serious cons-
traints on the proposed rate of development. Sources of supply and storage facilities
should be precisely determined. If importation represents a risk, then local seed produc-
tion and methods of expediting this must be given priority. Availability of seed must
necessarily have some influence on the planting rate of species previously selected for
silvicultural and utilisation reasons. A high standard of nursery technique is necessary
if the highest possible number of vigorous, plantable plants is to be obtained from a
given quantity of seed. When purchasing seed it is the cost per plantable seedling and
not the cost per unit weight which is of consequence. The annual requirements of seed and
seedlings and the cost should be readily calculated from the data collected.
Material and Equipment Resources
These fall into three main categories: those required for the administrative
organisation, for operational activities or for maintenance and support. Administrative
requirements include offices and buildings and minor items such as office equipment and
stationery which are common to any enterprise. Operational materials and equipment are
specific to plantation development; a general outline of such equipment and material is
given in Appendix C. Maintenance and support items include workshop equipment, transport
and spare parts. The critical factors with reference to stores are to select those items
suited to the particular work and scale of the project and to ensure that such equipment
or materials, together with spares, are available on site when required. This necessitates
the provision of ample storage.
Equipment offers a considerable range of options, and the types suited to the
work should have been determined at the appraisal stage.
-138-
The productivity of equipment is critical to the efficiency of a project. Evalua-
tions of the output of equipment may be of little value unless allowance is made for
variables and the basis of measurement is stated. Good productivity requires as full an
annual or seasonal utilization of equipment as possible. Scale of operation and opera-
tional data are required before moert stores or equipment requirements can be set out.
When the types of equipment and materials have been finalized, an assessment of the total
requirements by years can be drawn up for the full period of the project.
The purchase or capital cost of all project materials and equipment is required
for estimates, budgets and costing the total project requirements. For comparative evalua-
tions, the planner requires the hourly operating cost of the equipment, from which unit
productivity costs can be calculated. In the initial stages of a project this may have to
be estimated.
Human Resources
Man is the most important resource in the project, and due consideration of his
abilities and reactions is required in deciding on possible courses of action. The possible
sources of labour and staff require study, as they determine the need for additional in-
vestment in transport or housing. Employees benefit from a plantation project not only in
cash wages, but also from training, improved housing and security. Experience in Swaziland
points out the benefits of employees living in mixed communities rather than exclusive
project settlements of villages (Hastie and Mackenzie, 196?). A plantation project involves
many skills and requires managers, supervisors, mechanics, machine operators, administra-
tive and clerical staff, medical staff and both skilled and casual labour, In particular,
if a project is to be selectively mechanized, then provision for the employment of skilled
mechanics and operators is mandatory, and training will often be necessary. The avail-
ability and capability of the management and supervision require careful assessment.
The cost of human resources is the sum of salary or wages, social and fringe
benefits, leave and sick time. The manpower requirements of the project should be set out
for staff by years, categories and responsibility. Labour is similarly recorded, but oper-
ations replace responsibility. To estimate the annual labour force, a calendar of opera-
tions and labour inputs not only gives the necessary data but also allows fluctuations in
requirements to be smoothed out to provide more regular employment. Information on the
productivity and unit costs of labour will be extracted from operational data.
Financial Resources
Generally some indication of the finance available for the full project, or a phase
of the project, will hav^ been given at the outline or appraisal stage. The plantation
management plan should be tailored to fit this financial framework, but where finance
proves to be a critical constraint the case for an additional allocation should be made.
The total costs of the land, planting stock, material and human resources, plus contingency
represent the allocation required, and the range of these figures should be set out as ?
annual requirements for the entire project period.
It is important that the financial authority should understand that a plantation
is a dynamic enterprise not readily accommodated in the fiscal year concept. Plantation
operations such as land clearing, nursery and weeding are interrelated in time in that one
year's programme can affect both the previous year's and next year's programme. This means
that delays in funding or erratic allocations will not only affect the year of occurrence
but also past and future investments. Two possibilities of overcoming this problem are
either to consider the project as a capital investment until normality is achieved, or to
make funds available on three or five yearly allocations. The ready availability of funds,
however, does not preclude carefully planning their investment.
-139-
Operational Data
The data to be recorded in this section for all plantation operations are:
Unit of measurement - eg. ha f km or '000 plants;
Input - man-days, machine operating time, materials;
Output - units per hr f per day, etc. and
Cost - of each resource per unit.
These data allow a ready estimation of the productivity of men and machines and of the
total requirements of such resources for particular project operations. The collection
of operational data is critical and fundamental to the planning process. The information
must be the best known and may be extracted from costing records where available but, if
it is lacking, sampling work outputs may be necessary to provide indicative data. Opera-
tional data provide a basis for appraisal, for estimating resource requirements, and
budgeting; consequently it is vital that the source and reliability of all such data are
recorded. A project or plan is only as realistic and workable as the data used in its
design. The combination of resource and operational data into arithmetical calculations
leads directly to management prescriptions. A simple example for seed collection and
handling is shown in Appendix D.
Institutional Data
Institutional factors to be noted are mainly of a political nature, but include
the project legal framework and the commitment of the supervising agency in other fields,
such as training. Other factors on which information should be collected are the inter-
relationship of the local community and the project, facilities for multiple land use and
information on plantation research in progress but insufficiently advanced for appraisal.
The legal framework should provide appropriate and effective legislation and
regulations and the means to enforce them. It should also be determined that an adequate
management and administrative structure exists or will be available to run and service
the project.
THE PLANTATION MANAGEMENT FLAW
Purpose and Content
The plantation management plan forms the basis for management action and forecasts
and records in some detail what the plantation manager has to achieve over a period. In
the case of a 30 year rotation, the initial plantation management plan might cover some
five years or possibly less. The remainder of the project life will be covered by similar
periodic plans. This periodic planning allows a flexible approach to project management
and, the more stable and well defined the project environment, the longer the plan periods
can be. The presentation of the plan should be kept as simple as possible since effective
management requires some flexibility in the planned work programme. For complex projects
or problem areas, network analysis may prove a useful management tool in solving problems
or bottlenecks. An introduction to network analysis is given in Appendix E.
There is no set form for a plantation management plan, this must vary with local
conditions and requirements, but the three essential parts in any plan may be considered
as Part I, Direct ive ; Part II, Descriptive and Part III, Prescriptive*
I, Directive, consists of the instructions received by the project manager
from higher authority as to what the project is to accomplish. Part I cannot be altered
by the project manager, but only by the authority which issued the original directive.
-140-
Part II, Descriptive, provides information on the local environment, past history,
existing facilities in staff, roads, buildings etc., which is the essential basis for
management prescript ions .
Part III, Prescriptive^ prescribes how, when and with what resources future opera-
tions are to be carried out in order to accomplish the purposes of the project laid down
in Part I. Normally the project manager has discretion to alter these prescriptions in
the light of experience, in which case he must inform higher authority and amend the
written plan. Part III will require more frequent revision than Parts I and II. A concise
outline of the headings which could be included in a plantation management plan is as
follows.
Outline Plantation Management Plan
Part I Policy and Objectives
(Directive)
Policy
Objectives
Part II Basic Information
(Descriptive)
The project environment
Land availability and suitability
Institutional framework
Past management and history of the project
Part III Present State and Future Management
(Prescriptive)
Allocation of working circles
Detailed prescriptions of activities
- Plantation operations
- Other works
- Provision of resources
- Finance: expenditure budget and revenue
- Costings, records and control
- Map records
The Plantation Management Plan t Part I
Part I should be received by the project manager as a directive from higher autho-
rity. He is responsible for ensuring it is recorded in the written management plan. The
objectives of the project should be stated with complete clarity; if they are not, the
project manager should seek clarification before starting his own operational planning.
The Plantation Management Plan, Part II
Part II sets out the information basic to the project. It should include:
1) A description of the project environment including the location of the project
and information on geology, climate, hydrology and natural vegetation;
2) The land availability and suitability, described in the text, and supported by
tabular statements and maps. Where site classes are known these should be
defined and delineated;
-141-
3) The institutional framework of the project including its legal status, together
with its organizational structure;
4) The past management and history of the project, including a brief description
of project development and any past management information or data relevant to
project development. This section should note any salient features on which
the planned project programme is based. This section of the plan will be
brought up to date at the end of each plan period by adding what has been
accomplished in that period.
The Plantation Management Plan, Part III
Part III is the most important part of the plan, it contains a forecast of those
operations that are to be implemented by management. Where necessary, the project work
may be divided on the basis of different species or different silvicultural systems, by
the allocation of working circles. Plantation programmes of work are set out by years for
each working circle for the specified plan period [see, for example, Appendix P). The
plans for each year can readily be extracted and shown as ft annual programmes of work 11 for
all project activities. These annual programmes may then be further broken down by time
and area to serve as action plans for assistant managers and supervisors. See also page 146,
The detailed prescriptions of activities generally record the present state and
prescribe what future work or action is required under the following main headings:
Plantation operations and other works
Provision of resources
Expenditure budget and revenue
Costs, records and control
Map records
Plantation Operations and Other Works
This section covers the main plantation and building operations. The state at the
commencement of the plan is recorded and detailed prescriptions set out the method of
operating and the quantity and timing of forecasted inputs and outputs for each operation.
The main relevant operations are:
Plantation operations Other Works
Allocation of land Building and services
Surveys Maintenance of buildings and services
Establishment of nurseries Maintenance of transport and equipment
Raising plantation stock
Land clearing and preparation
Plantation layout and construction of access
Planting
Beating up
Fertilizing
Weeding
Brash ing/ Pruning
Thinning
Final felling
Fire protection
Road maintenance
-142-
The present state and prescribed work for each operation is very often set out in
tabular form. The prescription is usually supported by details of the estimated inputs
of labour f material and equipment for the main operations. The prescriptions concentrate
on what will be done, where and when, and the method may be covered by referring to a hand-
book or memoranda of instructions, or may be described in detail if such references are
not available.
The forecast of planting is affected by land availability f species growth and
yields, rotation and markets, and by availability of other resources. In the case of large
afforestation schemes it would be convenient to divide the available areas into a number of
even-sized planting blocks corresponding to the number of years in the rotation. In prac-
tice, it is more common to commence planting at a reduced scale and, as experience and
expertise are developed, to increase the rate. On the other hand, where the capacity
exists, initial planting may be at a rapid rate, which later will increase the options in
choice of rotation length, and in an era of inflation reduces total establishment costs.
Plantation layout includes the design and delineation of compartments, blocks, main
and secondary roads, rides and fire traces. This constitutes a major aspect of planning
which requires careful study for specific projects. The initial layout should be adapted
to the pattern of plantable soils, topography and natural features, but the design will
also be influenced by fire protection requirements and anticipated methods of logging and
extraction. Some projects have exceptionally large compartments of over 200 ha, but a more
general range is between 20 and 40 ha. Blocks may be of any size but are generally con-
fined to one year's planting.
Reading densities vary but are usually of the order of 1 to 4 km per square kilo-
metre, according to terrain. Only a small proportion of the roading needs to be high
standard; most can be low class roads. Initially, many of the lower class roads are either
unsurfaced or lightly metalled; upgrading of these roads for logging occurs closer to the
time of harvesting. Main plantation roads are generally constructed as all weather routes
to allow access for planting, maintenance and fire suppression; but they are not constructed
to standards suitable for logging. Some guidelines on the establishment of plantation roads
are given in Appendix B.
The major protection factors are fire prevention and suppression; the plan will
prescribe such firebreaks, boundary burning, controlled burning and other measures as are
considered necessary. Where there is a hi#i fire hazard the provision of radios or tele-
phones linked with fire lookouts will be required, together with the establishment of a
fire suppression organization. The risk of damage from biotic causes should have been
carefully evaluated during the collection of data phase, and the selection of plantation
species and techniques Aould be designed to minimize any such risks.
Provision of Resources
A general indication of resource requirements for the plan period will have been
set out in the previous section on plantation operations and other works. The prescriptions
in this section will set out which resources should be acquired by specific dates. The
main resource requirements are:
Personnel
Allocation of staff and definition
of responsibilities
Allocation of labour and calendar of
labour requirements
Training of staff and operations
Equipment
- Machinery transport and equipment
- Building materials
- Project materials and seed
- Essential spares
-143-
The development of plantations often requires the enlargement of the existing
forest service and, in some cases, the creation of a new management section to execute
the planned project. The plan should detail by years the personnel required to implement
the programme, such personnel to include professional forest managers, foresters, techni-
cal assistants and various supervisor grades. The responsibility of the manager and his
supporting staff should be defined. The allocation of labour comprises a summary of the
prescribed labour requirements to implement the component operations and is set out as a
calendar of operations, a sample of which is given in Appendix 0. The preparation of
these calendars allows the labour requirements to be smoothed out both within a year and
over the plan period, to avoid erratic dismissals and ensure continuity of employment for
the major labour force.
As the plantation area deve lops f there will be a steady demand for additional staff
and it will be necessary to plan the provision of facilities for the various grades of
staff to be trained in plantation management and operations. As labour will be required
to develop skills in silvicultural work, nursery work and, in some cases, in mechanization
or irrigation, it will be essential to provide adequate training.
The prescriptions for equipment and material set out what items are required by
what date if operations are to be completed as planned. A monthly calendar of machine
requirements, similar to that for labour in Appendix Q, will be required. The requirements
may be estimated on gross known requirements such as one tractor per x ha, or amount of
fertilizer per 100 ha or perl 000 plants in the nursery.
A breakdown of material and equipment inputs will have been recorded under indi-
vidual plantation operations and other works, and this can either be collated to give an
estimate of requirements or to cross check gross estimates. It may be necessary to seek
specialist advice for the specifications of such items as machinery, transport and building
materials. Where delays in obtaining certain items can be foreseen, advance ordering is
necessary, and for many materials and spares the setting up of a strategic reserve in
storage is essential. Late arrival of stores frequently acts as a bottleneck to implemen-
tation; ordering of equipment, therefore, warrants careful planning and attention to detail
so that it is done both timely and correctly.
Appendix C gives an outline check list of equipment and materials which could be
required for plantation development.
Finance: Expenditure Budget and Revenue
The plan generally includes an expenditure budget. This budget represents the
estimated cost of all the resources required to achieve the prescribed programme. It is
usually drawn up by years and is set out under such functional headings as:
Land clearing and preparation Building maintenance
Nurseries Equipment and materials
Plantation operations Equipment maintenance
Capital cost of land & building Administration and staff
The approved budget is the authority for the allocation of funds to the project. If
annual financial allocation is prescribed, then extraction of the annual data from the
budget can serve as yearly estimate submissions. When release of funds is requested
during the implementation period, some allowances may have to be made for inflation,
changes in technique and possible increases in operational efficiency.
The plan will prescribe how expenditure will be recorded. Expenditure is subject
to audit and the records must account for all funds disbursed, and should give a measure
of the overall expenditure of the project at any point in time. When, during implementa-
tion, actual expenditure is compared with the budget for a specified period, this should
give some measure of planning and management efficiency. Expenditure for labour and staff
is usually recorded on muster-rolls or pay sheets, while equipment and store charges are
recorded by requisition and receipt.
-144-
Revenue is generally slight during the establishment phase of a plantation, but is
generated fairly rapidly throu#i the thinning to the final felling phase. A forecast of
revenue by years is usually made. It is essential that the plan prescribe an adequate
system of accounting for such revenue, recording the amount, the product, the source and
the date of occurrence and payment.
Expenditure and revenue are usually recorded in debit and credit ledgers, and
balances may be taken at defined intervals but always at the end of the financial or
accounting year.
Costings, Records and Control
Complex costing and recording systems are costly to administer and very often run
into difficulties and fail. It is essential, therefore, to keep them simple, particularly
at the field level, and to record only essential data. The plan will prescribe a system
of project control. Such control is concerned with 1) maintaining the work output at the
levels set in the programme of work and 2) keeping the costs within the limits estimated
for particular operations in a particular period.
There are many types of "periodic progress reports 11 which simultaneously record
work completed and give a breakdown of project costs. Such progress reports, which are
often compiled on a monthly basis, must be accurate and submitted punctually. The reports
generally record for defined periods the items given below as the headings for a sample
form:
Operations
ny\/3
Inputs and costs
Wrmlr
TVi-i 4-
Cost Code
Labour
Cost
Plant
Cost
Materials
Cost
Total
Com-
un?.u
Cost
vehicle
pleted
&
machines
The physical inputs are measured by defined units such as man-days for labour, hours for
plant or tractors, kilometres for vehicles, and number, weigjit or volume for materials.
Standard unit costs are periodically laid down for these items and used to calculate input
costs. The physical outputs are measured by such units as metres for roads, hectares for
planting or weeding and thousands of plants for nursery production. The report may also
incorporate at this stage, or a later stage 1) the plan forecast of outputs and costs and
2) cumulative actual outputs and costs, and these figures form the basis of the prescribed
control system. It is usual to give a code number to each operation, for ease of operation
and for possible computer processing. The project report gives a breakdown of costs; under
plantation operations, for example, there would be a number of subheads covering land pre-
paration activities, phases of planting, mechanized weeding, hand-weeding, fertilizing,
pruning and so on. The plantation or project manager uses such costs for economic apprai-
sal and control. Where there are variations in actual unit costs, it should be possible
to select and develop the more efficient alternatives. It is necessary to train super-
visory staff in compiling such reports and to impress upon them the value of data collected.
In areas where there is a shortage of adequate field management, reports may include physi-
cal data only, and costs may be applied centrally. It is equally important that management
should check reports without delay, record appreciation of efficient outputs and inquire
into significant deviations from budgetary provisions or into widely variable unit costs
for the same operation in different areas.
The annual total of operation costs for labour and materials should be readily
reconciled with expenditure for the same period. The reconciliation of plant, vehicle and
machinery costs is a little more complicated but, providing the basis of unit costs for
equipment is soundly designed, a reasonable reconciliation can be achieved. The flow chart
of cost records in Appendix H outlines a costing process.
-145-
The fundamental plantation record is the compartment register. The compartment
register should give a comprehensive and precise description and history of the compartments
comprising a given plantation. The register may be a simple or a complex document, gemer-
ally recording the following information!
A detailed map of the plantation area;
Details of physical features - elevation, aspect, exposure,
slope, land form, geology, soils and vegetation;
3) Site characteristics including planting suitability and site
quality classes and
4) History.
The plan will prescribe that all work in a compartment should be recorded in this register
which will contain a form or forms to record!
Site preparation and planting or sowing.
Tending operations.
Crop assessment and
Yields.
The physical details of work done in a compartment can readily be extracted from progress
reports. Some compartment registers also record costs but, unless there is a particular
reason to record costs at this level, the register is best maintained as a physical his-
toric record. If, at some future date, the cost of operations in a particular compartment
or group of compartments is required, it should be possible to extract this from the cost
system records.
Map Records
The management plan, in addition to the compartment register, should have some or
all of the following maps:
1) Plantation locality map (at liJO 000 to 1|100 000 scale) and
management maps (at 1t20 000 to 1s30 000) ;
2) Plantation soil and planting suitability map;
3) Plantation vegetation map;
4) Plantation organisation map - showing present roads, compartments,
nurseries and planned layout ;
5) Planting and site preparation map - showing present state and
planned programme;
6) Plantation tending map or maps - showing present state and
planned programme for major operations - and
7) Fire protection maps - showing present state and planned programme.
The management maps can be prepared on a basic map with a series of overlays for the
different information. The number of maps may be reduced by combining certain data from
separate but related sheets. The management maps form a visual record and control of
plantation operations, and the plan will prescribe that specified management maps will be
"brought up to date on a periodic or annual basis.
-146-
In conclu8ion y it should be noted that the plantation management plan can take many
forms, and it is only a tool for translating policy and objectives into reality* The real
measure of efficiency is not how well it is designed but how successfully it is implemented*
Oood management needs not only good planning but good implementation*
ANNUAL PROGRAMME OP WORK
This covers the next operational year and needs to be prepared a few months in
advance of the start of the year y to leave time to have the budget approved and to provide
the resources needed (Fraser, 1973)* The planning can be done on forms divided into monthly
or weekly periods giving a forecast of the quantity of work to be done during each period
by operation. After a plantation management plan has been smoothly executed for several
years, there should be little difficulty in compiling the annual programme of work directly
from the plantation management plan*
BIBLIOGRAPHY AND REFERENCES
Allan, T.G* Planning of savanna plantation projects. In Savanna afforestation in
1977 Africa, pp. 220-233. Rome, PAD.
Bands, D.P. Organisation for the production of a district forest management book.
1962 Lusaka, Forest Department. 13 P.
Ball, J.B. Cost accounting and the maintenance of records for monitoring and evaluating
1977 plantation projects. In Savanna afforestation in Africa, pp. 234-246.
Rome, PAO.
Cooling, E.N.Q. Compartment registers for pilot plantations and demonstration areas.
1976 Industrial Forestry Plantations, Turkey. Izmit, PAO* PO: DP/TUR/71/521,
Working Document No. 26. p. 13
Dargavel, J.B. et al* An information system for plantation management. Commonwealth
1975 Forestry Review, 540): 27-37.
PAO. Report of UNDP/PAO seminar on the methodology of planning land and water
1972 development projects. Rome, PAO. 128 p. Irrigation and Drainage
Paper II.
PAO. An introduction to planning forestry development. Rome, PAO. 86 p.
1974 PAO/SWE/TP 18.
Poggie, A* A forest working plan manual; report to the Government of the Sudan* PAO,
1970 Rome. 105 p* No. TA 2869.
Fraser, A.I. A manual on the planning of roan-made forests. Rome, PAO. FOt MISC/73/22,
1973 P. 129.
Fraser, A.I. A manual on the management of plantation forests. Penicuik, Scotland,
no date International Forestry Consultancy, p. 126.
Frith, A.C. The Fiji Forest Department costing system. Forest Management Project, Fiji.
1976 Suva, FAO. FO: DP/PI J/72/006, Working Paper No* 4. p. 47.
-147-
Grayson, A.J. Afforestation planning at the national and project levels. In Proceedings
1967 of FAO World Symposium on Man-Made Forests and their Industrial Importance,
Vol. 1, pp. 551-572. Rome, FAO.
Gittinger, J.P. Economic analysis of agricultural projects. Baltimore, U.S.A., The
1972 Johns Hopkins University Press. 221 p.
Grut, M. Records of costs and revenues in forestry. Industrial Forestry Plantations,
1975 Turkey. Izmit, FAO. Working Document No, 5, FOi DP/TUR/71/521 . p. 28.
Hastie, W.F. <fc Mackenzie, J. Planning an integrated forest programme. In Proceedings of
1967 the FAO World Symposium on Man-Made Forests and their Industrial
Importance, pp. 905-922. Rome, FAO.
Johnston, D.R. et al. Forest planning. London, Faber and Faber Limited, p. 541 .
1967
Kingston, B. Final report: Plantation management. Industrial Forestry Plantations,
1977 Turkey. Rome, FAO. FO: DP/TUR/71/521 . Working Document 29, p. 127.
Krug, H.P. Planning for afforestation and planting in Brazil. In Proceedings of FAO
1967 World Symposium on Man-Made Forests and their Industrial Importance,
Vol. 2, pp. 1219-1235. Rome, FAO.
Levingston, R. Plantation management procedures for large-scale plantations in Peninsular
1975 Malaysia. Forestry and Forest Industries Development, Malaysia. Kuala
Lumpur, FAO. 205 p. FO: DP/MAL/72/009 . Working Paper 36.
Savory, B.M. Plantation planning for conifers in Northern Rhodesia. Lusaka, Forest
1962 Department. 10 p.
Wendelken, W.J. Records of plantation history: expenditure and revenue accounts. In
1967 Proceedings of FAO World Symposium on Man-Made Forests and their Indus-
trial Importance, Vol. 1, pp. 605-638. Rome, FAO.
Watt, G.R. The planning and evaluation of forestry projects. London, Commonwealth
1973 Forestry Institute. 83 p. Institute Paper No. 45.
-149-
Appendix A
CRITERIA FOR SUCCESSFUL LINE PLANTING
(By H*C, Davfcins, quoted by A.F. Lamb, 1969)
There are a number of criteria whioh must be met if a system of enrichment is to
produce a satisfactory stand of timber trees* These criteria have been clearly enunciated
by Dawkins and are quoted with his permission:
In the sense used here, enrichment by line-planting is the establishment of a tree
crop to be closed at rotation age t in lines spaced at intervals equal to or slightly
greater than estimated final-crop crown diameter*
There are five necessary conditions for line planting, in addition to the normal
requirements of healthy plant establishment!
1* There must be little or no demand for thinnings in the area concerned*
If thinnings are required, the method is unsuitable; if large timber
and veneer logs are in demand, the system is suitable*
2* The species planted must be fast-growing (1*5 m of height per year as
a minimum), naturally straight and self-pruning, i*e* generally of the
colonizing or gap-filling, light demanding type*
3 There must be no upper canopy; only clear-felled, clear-poisoned or
low secondary forest is suitable*
4* The regrowth between the planted lines must be non-inflammable; or
control of fire must be complete*
5 Browsing animals must be absent, scarce or of negligible effect on
planted trees*
Provided all five conditions are met, the method can out the cost of a final crop
to less than a third of what would be incurred by close planting* The technique then
requires the following:
6, Planting lines should be spaced equal to or slightly more - up to
20% more is reasonable - than the expected crown diameter of healthy
final crop trees of the species concerned* 'The reason for this is
to prevent any possibility of serious bet we en-line crown competition
before maturity, to save on establishment costs and to give more
scope for possibly superior species whioh may arise naturally
between the lines*
7. Plants should be spaced along the lines at approximately one-fifth
of the spacing between them to allow a selection of about one-in-
four for the final crop* If poisoned overwood is likely to be
abundant, as in very lightly felled natural forest being planted,
then up to 30$ losses must be expected and spacing in the lines
should be nearer 1/6th to 1/7th of spacing between lines* Only by
this means can good form of the final orop be assured*
-150-
8* Planting lines must be w*ll-oleared f about 1.8 m wide at first, and
made easy to move along, at least along one side of the planted trees,
by removal of most if not all woody snags* Once planted, the lines
must be kept olean and no overhanging or threatening growth tolerated*
Sinoe this clearing work is oonfined to a very small fraction of the
area, labour costs are low and several cleanings (sometimes up to six
or seven are necessary) can be afforded in the first twelve months*
9* Plants must get away to a quick start* For most species this means
using potted stock; stumps or striplings axe not likely to be
suitable* Cedrela has shown itself capable of starting from direct
seed, but this is quite exceptional*
10. Planting must follow immediately on clearing the planting lines;
clearing in the early dry season, and planting three to five months
later in the early rains is a thoroughly bad technique and will result
in at least two more clearings than otherwise* Poisoning of the
upper canopy also should be timed to let in the light at time of
planting, not before, it is recognized, however, that this is not a
precise possibility*
11* Trees arising between the lines, unless superior in value to the
planted species, must be out or poisoned immediately they "threaten"
the plants, i*e* before they overshadow them. The greatest threat
is from Musanga, Trema and Maoaranga* Similarly, climbers over-arching
from the bush regrowth beside the lines, must be vigorously out baok
before they overshadow the plants, provide ladders for other climbers or
obstruct quick access along the lines*
12. Thinning along the lines is a matter of selecting the stems of
superior form and height* (Unless the disparity in size is very great,
form and height should both be regarded as more important than mere
girth). The first thinning will generally be at three to four years,
by which time the trees should be well above the shrub and climber
regrowth. It will probably require about 50$ culling of the crop.
The above five principles and seven technical guides must be taken very seriously*
Line-planting has very commonly failed and has a bad reputation among English-speaking
tropical foresters because one or other of the principles has been flouted. If all the
above are followed for i speoies sensibly chosen, the technique has a very high ohanoe
of success in tropical forest conditions*
-151-
Appendix B
OH UPLINES FOR THE DESIGN
AND ESTABLISHMENT OP PLANTATION ROADS
L.R. LETOURNEA1J
Pulp and Paper Industries Development Programme
FAO f Rome
PLANNING
The object and purpose of establishing a plantation road system is to provide a
network of roads which is sufficient to enable planting and tending to be carried out in
timely fashion and at the lowest possible overall plantation cost, while providing rapid
access for protection purposes and a network of roads suitable for the eventual extraction
of the final product.
There are no hard and fast rules for planning road networks in areas which are to
be afforested. Any plan must take into account both the immediate and future requirements
for roads. Since, initially, access will be required for the planting operation, the
planner must consider the rates of planting which can be achieved with different road
densities and spacings. These are not easy to determine without reliable data on the
productivity of planting crews, off-road capabilities of vehicles and road construction
costs, but the road plan must aim at reaching a balance between planting rate, as affected
by carrying distances, and the cost of road construction.
The need for rapid access in case of fire or other emergencies must be considered in
the road plan. In particular, each major plantation block should be reachable by more than
one all-weather road, so that access of fire suppression crews and equipment would still be
possible even if one main road was blocked or otherwise impassable*
When planning the road network the planner must also bear in mind the ultimate use
of the produce from the forest. Since in most cases the forest being established is to be
harvested, care must be taken to ensure that the location of major roads to be constructed
for planting will be located to suit the future logging methods. It is not always possible
to know in advance whart logging system will be used ten or even twenty-five years hence, but
the planner must avail himself of the best existing data on logging methods to assist him in
making his decisions.
-152-
Although the full road network should be planned before plantation establishment
begins, costs oan be minimized by delaying construction until the roads are actually
required. It should be remembered that road costs form a large part of total plantation
costs. Roads for planting and tending are therefore only built as they are needed and
only to the lengths and standards required for these operations. During the establishment
phase it ia not necessary that roads be built to logging road standards with high load
bearing capacities since unnecessary expenditure would be carried the length of the
rotation, thus raising overall cost. However, the basic network will be available for
updating and extension for later harvesting operations.
In areas being converted from natural forest to plantations, the planning of the
road network prior to primary logging, as well as the physical location and construction,
is of utmost importance for, unless unusually stringent conditions and additional road
requirements are imposed, this network will be written off against the logging and will
not be a financial burden to plantation establishment.
ROAD MAPS
Road locations should be indicated on maps of suitable scale; contour maps are
best suited for this purpose. A map scale of 1:25 000 serves well for moderate sized
plantations in the order of 25 000 hectares since it can be hung on the wall for easy
viewing and is not too small to show necessary overall planning detail. This master map
should show all existing and proposed roads, important natural physical features such as
streams, mountains and such other major details as planting blocks, firebreaks, lookout
towers, nurseries and buildings.
Maps showing roads in annual planting areas or plantation blocks should be
available at a scale larger than for the master map and should show all relevant data in
greater and finer detail. A map scale of 1:5 000 gives good detail and is compatible
with the 1:25 000 scale of the master map.
For roads in which even finer details are required (e.g. for rebuilding or
tendering), maps and construction plane should be at a maximum scale of 1:1 000. Where
necessary, profiles of roads should be produced using a ratio of horizontal to vertical
scales of 10:1 or 20:1 as dictated by the terrain.
ROAD INDEXING SYSTEM
A road indexing or numbering system, with accompanying map, is an essential part
of any forest plantation programme. Roads must be numbered so that staff and others can
be easily directed to any part of the plantation. The system must be systematic and take
into account the various olasaes of roads and the major areas they serve. Since roads do
not often stop within any one annual planting area, a designation by years is difficult to
devise, however, a simple numerical system is easy to formulate and is effective.
ROAD CLASSES
A system of road olasies designed to meet the needs of planting, fire suppression
and efficient supervision is given below. These classes are considered adequate for the
establishment of a plantation in one large contiguous area; however, as experience is
gained the planner should not hesitate to adjust the system to more adequately meet the
plantation requirements and/or to lower ocstfl. The basic network when properly aligned
to fit the terrain will also serve the harvesting function.
-153-
01 asses
1 Main Road
This forms the main access from the highway or public
road system to the headquarters area and to the
extremities of the plantation. It provides speedy,
all weather travel*
Roads
This secondary system of roads is designed to move
traffic from the main road to the planting areas in
all weather, at moderate speeds. The branch roads
form the major access system within each annual
planting area.
3 Spur Roads
These are basic utility roads designed to move planting
and tending crews to work sites at generally low speeds
in four-wheel-drive vehicles. They will not be all
weather, with the exception of portions of the longer
spurs which will be surfaced ao that the end of any
spur is not further than about 1.5 km from a surfaced
road, as measured along the spur.
4 Planting Tracks
These simple, bulldozed and levelled tracks are the
most numerous of all classes of roads and serve the
basic needs of planting and tending. They are suitable
for four-wheel-drive machinery and have an absolute
minimal number of culverts and bridges.
Road classes 1, 2 and 3 are located and staked on the ground prior to logging and
land clearing. Class 4 roads are located after clearing and burning has been completed;
however, location prior to clearing, if possible, is advantageous. Road classes 2, 3 and
4 are built in the proportions of 1:2:4 or as near as practical to this.
DENSITY AND SPACING OF ROADS
The density of road network required will vary significantly from one plantation
to another, but a figure of 2.5 km of road per km 2 of gross plantation area is a reasonable
estimate of the average retirement of many plantations. At this density, and at the
proportions of 1:2:4 f the number of kilometres of class 2, 3 and 4 roads required would be:
2
Road Class Km of road per km of
Gross Plantation Area
2 branch
3 spur
4 planting track
Total
-154-
Nain roads may be included in the above overall distances when any sections oan be
used for plantation work.
At this density, average spacing between roads would be 400 m. Lacking accurate
information on the capabilities of planting teams, this is a reasonable estimate of the
planting track spacing on which initial planning oan be formulated. Later spacing of
planting tracks should be based upon the distance at which a planting team can reach the
optimum daily average number of trees planted. As experience is gained and efficiency
improves, therefore, the spacing and overall length of planting track required may change.
The spacing will also vary to some extent due to terrain.
The location of branch and spur roads will also often be dictated by topographic
constraints but will, in general, adhere to the above quoted density*
ROAD STANDARDS
Standards should be applied in the light of topographic, soil and weather conditions
as they exist, or as they affect road construction costs and rate of construction. In other
words, although standards will be laid down to which the location engineer will try to
adhere, he should alter these to suit conditions as he finds them, bearing in mind that the
raised or lowered standards must not have a major effect on the usability of the road. In
other words, he should bear in mind that the roads are being built to achieve the lowest
possible overall plantation cost at maturity.
Road standards for two terrain classes and the four road classes are detailed in
table A1. The following notes refer to the standards in the table and their application.
Right of Way Width
This represents the piece of land set aside for the road. It is the overall width
which is to be cleared and in which trees are not to be planted. This extra distance, over
and above the actual road works, facilitates more rapid drying of the road after a rain,
makes allowance for future widening and improves visibility.
Subgrade Formation
Ample allowance rhould be made for the traffic density contemplated and to allow
drainage away from the running area. In mountainous terrain where slopes are extreme, the
road bed must be full bench (not on fill). All fills must be compacted.
Side Cuts
Side cuts will vary with the topography, but as a general rule should be a* a slope
of 1:2 or less.
Turnouts (Laybyes)
Turnout* need not always be evenly spaced, but should be positioned so as to be
used to maximum advantage to allow vehicles to pass and to avoid accidents. Turnouts will
also be used as paricing places for vehicles which carry crews and materials.
-155-
8
*-
11
03
m ir\ e
-H | |
CVI
^^ i ^i;
J^ CO
O 00
O CO M O >*
O << Pi -H t> (H
nj H
rH ^
^ -5
^"
t 9 ? CO d o3
Pu
53
d PI
CM ir\ vo m o
r\i
O O O ro ^~
^ C
o co a
Pi W
*~" rA O C\J *~
* - rn ^
"S CP
Pi
5
d *
CQ
J3
X N
d
SrH | W *d
rH ^J Pi f)
H 00 O X5 Pi
.s s
H
LP\ m vo m s
CVJ
oo o o m *-
**"" ^O W
TJ ^3 CO ttf) -p '
O -H hp d H >
05 Pi
rO O C\J O
^-
*^K O O rH Pi 4) O
P W
*
g
4> T^J |
s
'd*
P C rH Pi
4) OJ rH -p 00 Pt
P< -H CO Pi 4>
5
05
o LP> T irsv x
CO O
VO GO U"% VO *
GO M
O P< P. O d -H 4)
SB!
rO T-
^"
rH .H 4* T*
SP
rH
^ |
H &
oS
C\'
^ XJ 09
p q
.3 2
03 rH E-l
-H | |
rn d
H
O CO
O <J (L, .H 4) Pi
& *
as
fl>
EH
bD
^
d
O
H Pi
C 1
a
co m vo m o
o o o m *-
O Of} Oj
rH W
rO O CM
^>
* op
Trf -
r
^..^
SrH | 0) TJ
rH ^ P. 4)
x:
r*
H CQ 4) X3 Pi
t>0
H
OJ
.s s
*p ^ ^ ^^
00 2 vo "^ 7i
O M Pi O -H 03 O
rH Pi
O rOO
^-
H PP
O
^^
4) TJ 1
"8 a
H
IT*
-P d rH Pi -
3 rH 4* CO Pi
H 00 Pi 4)
E 'S
o m *- LT>V_X
co O
cvj 5
r
rO *""
O PH Pi O d 'rH 4)
O O O rH -H 4P Ti
f) ^-^
rH
^^
Sflt v-_X
r-I ^
a
PI g ) -p
| | ^ff
CO
<4 ^
si
1 1 CO 3^
^
11
S 3 '^ ^ *H
XX 03 P-, DC
e
o
A ^S^Q
"3^2* e ^3^
^^
-
^-^-^ | ^-*^
g
S *
H
^ d
!> ^ '
A, 'e
-, ^^
CM t) H 4>
-S S d
CO 0)
-P h XJ g
*j & $
CO f CO
3 S
* "S
^ f: e
03 Pi H
PI )
p K
p.
s.
o
p
o
Pi
CM
O
CO
Pi
O
5
4>
00
Pi
4>
00
(0
4>
00
|
d
H
4>
4*
i.s
s s
P -H
d -p
o o
J 2
00 4 s
H CO
rH d
2
o3 o
S
"T
ttf) -H
d o
'H >
P, 05
^ C
p
4)
rH 4>
,0 CO
03
O XJ
I-
d a
CO 1)
p
CO
o
J ?
fc o5
TJ O
a a
Pi rH
O <J
4) Pi -P
00 4) 00
00
00
H
E
&
SP
I
O
-156-
In flat country Bpacing can be equidistant f however, in mountainous terrain turn-
outs should be placed at either end of the sharpest curves or, in the case of a road
curving around a sharp ridge, the turnout can be placed on the outside of the curve, at
the nose of the ridge, to take advantage of the fill area and also to ensure good visibility.
Borrow pits should be used as turnouts wherever possible*
For those roads which are to be surfaced the turnouts should be surfaced to the
same standards.
Pavement
Surfacing material should be of either hard, crushed rock or of best quality
laterite with ample ferrous concretions or other suitable materials approved by the
construction supervisor.
The pavement thicknesses as laid down in the table of standards, are compacted
thicknesses and are those considered to be suitable for the traffic in the establishment
phase. These are not, however, to be construed as rigid standards, but might be varied in
the light of what the supervising engineer finds, as construction experience is gained in
the area.
On both the main and branch roads the running surface widths should be ample for
the type of vehicles expected to use the road such as trucks carrying planting stock,
fertilizer and work crews, not normally heavily laden nor of extraordinary large size.
Much traffic will be of the type provided by foui^- wheel-drive vehicles. The surface width
of the road will however gradually widen through the shifting of material from the centre
to the shoulder; this will be caused by the passing of vehicles which throw material and
by the maintenance road grader which will spill small amounts as it makes its passes.
Eventually, for roads with wide formations, passing will be possible without the use of
the turnouts. Similarly, superelevation will be built up at the curves by fast moving
vehicles. Adequate camber (crown) should be provided to ensure proper drainage.
Spur roads need not be surfaced along their entire length. It is normally
sufficient to surface only some stretches with the criterion that the end of any spur
road is no further than 1.5 km away from a surfaced road, as measured along the spur.
Estimates often indicate that only some 20 percent of the total length of spur road
requirements will be surfaced.
It should be noted that in some regions which are lacking in surfacing materials,
the cost of surfacing is often the major portion of total road construction costs.
Curvature and Travel Speeds
The minimum radii of curvatures have been set at a level at which minimum travel
speeds, on class 1, 2 and 3 roads, can be maintained. By setting these standards as the
minimum, it can be expected that most radii will be greater, thus allowing for greater
speeds and thereby maintaining minimum average speeds over the longer distances.
Average travel speeds of 65, 50 and 35 km per hour, for main branch and spur roads,
respectively, have been used as the criteria which will provide for reasonable travel for
work crews and good travel speeds for fire suppression crews, bearing in mind the added
road costs which would accrue by putting in curves with much longer radii. These speeds
might be slightly lower in mountainous terrain, for which minimum radii as shown in the
table of standards have been shortened.
-157-
Qradients
Road grade standards have been set to counter the effect of erosion and to keep
maintenance costs to a minimum as well ELS to ensure effective travel time. Long sustained
grades should be avoided by the allowance of grade breaks in the profile.
Drainage
Since it is impossible to discuss the amount of rainfall which any one plantation
area might receive, it will suffice to point out a few factors which should be considered
by plantation managers, in providing adequate road drainage.
Areas with a heavy annual rainfall will need a better drainage system than those
in dry areas; however, it must be remembered that in some regions, though the annual
rainfall can be considered as moderate (say to ? 000 mm per year), a large portion of this
might arrive in a short period of time, and thus the drainage system must be geared to
handle the large periodic volume.
The forces exerted by large volumes of water, collected and diverted by a road
system can cause severe damage to roads and extensive erosion. These effects can be
overcome through proper ditching and channelling of the water to points where it can do
less damage.
In flat terrain, ditches should be constructed on both sides of the road with
adequate cross drainage and lead-off, whereas in mountainous terrain the upper side should
be ditched. In rolling terrain, culverts should be placed at the bottoms of fills.
In all types of terrain, roads must be constructed to cross watercourses in such
a manner as not to impede the natural flow of water. This cam be effected through the use
of the proper size of culvert or bridge. Culverts should be laid so as to prevent ponding.
Water should not be allowed to run (and gather more water) for long distances in ditches
on long, continuous sloping roads; its flow should be broken by barriers and led off by
adequate cross drains at appropriate places. Culverts should not be situated so as to
drain onto fill unless special structures (e.g. rip-rap) are built to preserve the fill.
On roads with long continuous grades, where surface water is liable to collect
and run down the running track of the road, removing surface and subgrade material in its
course, open surf ace -drains should be constructed to remove this concentration and
prevent the deterioration of the road.
In general, bridges can be of simple construction and if built of the most durable
woods should last at least the life of one short rotation. Two types of bridges are
commons one having timber running planks and one covered with soil and surfaced. Both
types make use of log stringers which rest on either cribbing or on a mud sill.
Cross-Sections
^rpioal crosssections for main and branch roads are shown in Figure B1.
Maintenance
Maintenance must be a continuous procedure once the road system is started. This
can be effected through the use of maintenance machinery (e.g. road graders, tractors,
front-end loaders, tipper trucks) which maty (preferably) be owned by the project and
operated by a maintenance crew. Maintenance crew labourers should fid so clean culverts and
ditches and clear brush from around ditches and tight corners on a regular basis.
-158-
Pigure B1
CROSS-SECTIONS OP TYPICAL
MAIN ROAD
(Sidehill Cut)
Subgrade (5m)
Pavement width (35m)-
of way width (20m)
BRANCH ROAD
(Sidehill Cut)
Subgrade (4m)
Pavement width
(3m)
Right of way width (15m)
-159-
BIBLIOQRAPHY
British Forestry Commission. Forest road planning. on don, Her Majesty's Stationery
1976 Office. Forestry Commission Booklet No. 43.
Bybaok, P.O. Forest Roads* Forestry College Project, Kepong (Penninsular Malaysia)
1976 Kuala Lumpur, FAO. FOtSF/MAL/71/531.
MoNally, J. Logging and log transport in man-made forests in developing Countries.
1974 Rome, FAD. 134+ P. FAO/SWE/TF 11 6.
-160-
Appendix C
AN OUTLINE OF EQUIPMENT AND MATERIALS FOR AN AFFORESTATION PROJECT
OPERATION
ECJLJIPMENT
MATERIAL
Land clearing
Ground
preparation
Nursery
Planting
Maintenance and
protection
Road
construction
Survey equipment
Crawler tractors
Anchor chains
Dozer blade
Stinger
Front-end rake
Root plough
Tractors 50-100 hp
Disc ploughs
Angle dozer blade
Wheel tractor
Trailer
Loader attachment
Loader attachment
Sprinkler equipment
Soil mixer
Hand tools: spades,
forks, hoes
Spraying equipment
Tractors, 50-100 hp
Trailer
Tractor, 50-100 hp
Soil cultivators
Pruning saws
Fire towers
Fire engines
Water pumps and
hoses
Bulldozers
Tipping trucks
Graders
Excavators
Rollers, rubber
tyred
Herbicides
Fuel and oil
Hand tools
Aerial photographs
Herbicides
Fuel and oil
Hand tools
Fertilizers
Pots
Potting media
Insecticides
Fungicides
Herbicides
Fuel and oil
Hand tools
Fertilizers
Fencing stakes
Fencing wire
Hand tools: spades,
mattocks
Fuel and oil
Tree carrying
containers
Fertilizers
Herbicides
Fuel and oil
Insecticides
Hand tools
Culverts
Fuel and oil
Road ballast and
gravel
Bridge materials
Cement, Gelignite
-161-
Appendix D
PLANNING OF SEED COLLECTION AND HANDLING
(Example)
I. Background Data
SEED DEMAND
1. Species Eucalyptus carnal du lens is
2. Plants per ha
a) Number planted 1 110 (3 x 3 m)
b) Add field replacements at 20$ 222
Total requirement - plantable
plants 1 322
(d) Add losses and culls in
nursery at 15$ / 235
(e) Total requirement - germinated
seeds 1 567
Ditto rounded upwards 1 600
3. Estimated number of germinated
seeds per kg of unc leaned seed 400 000
4. Kg uncleaned seed needed per ha
of plantation 0.004 kg (c. 250 ha per kg)
5. Annual planting area 250 ha
6. Annual requirement of seed 1.0 kg
J/ from "Report on the FAD/DAN I DA Training Course on Forest Seed Collection and Handling",
Vol. II. Rome, PAD. FORiTF - HAS 11 (BEN), 453 P., 1975.
2/ Losses and culls represent 15$ of the germinated seeds. This is equivalent to
approximately 18$ of the surviving plantable plants.
-162-
B.
C.
D.
SEED SUPPLY
7. Sources for seed procurement
8. Seed harvest 9 ezpeoted yield/ha
9. Minimum area of seed stand required
10. Area of seed stand available
11. Seed harvest f periodicity
12. Season of collection
13 Special problems of collection
14* Rate of seed collection
Local seed stands
5 kg per ha
0.2 ha
1.5 **
Annual | reliable from stands over
10 years
Early dry season, June - July
None
Equivalent to 100 - 200 g unoleaned
seed per man-day
15 Length of period for seed extraction 10 - 15 days (sun-drying)
16. Special problems of extraction and
cleaning
SEED STORAGE
17* Normal season of sowing
18. Length of period between collection
and sowing
(a) if sown in same year
(b) if stored for more than one
year
19. Storage capacity needed
(a) Net seed space at S.O. 0.5
500 kg per m^
20. Special problems of storage
PRETREATMBNT. TE3TINQ t SOWING
21. Special problems of pretreatment
22. Special problems of testing
23* Special problems of sowing and
seedbed handling
It is not possible to separate the
chaff from the seed. Both chaff
and seed are therefore sown
together.
Late dry season, September - October
3-4 months
Not applicable
.002 m 3 (one jar of two-litre
capacity)
None
None
It is difficult to separate the chaff
from seed. Identification of the
species from seed is not possible.
The seed being very small has to be
sown with sand.
-163-
B.
C.
OOLLBCTION
1. Method* recommended
2. Equipment /transport
recommended
3. Staff/labour recommended
4. ReraarkB
EXTRACTION AND CLEAN IN Q
1. Methods recommended
2. Equipment recommended
3. Staff/labour recommended
4. Remarks
STORAGE
1. Methods recommended
2. Equipment recommended
3. Staff/labour recommended
4. Remarks
II. Estimate of Needs
Climbing
C.
PRETREATMENT
Safety belts and lines, boots and spurs.
Temporary use of land rover.
5-10 man-days and one supervisor
Climbers should be insured. Seed stand
protection and management must be ensured,
since normal stands, out on 6 year ooppioe
rotation, bear very little viable seed.
After sun drying, capsules are to be
vigorously shaken and sieved manually.
(1) Tarpaulin
(2) Sieves
A forest guard and two labourers
No cleaning need be done as the seed is
sown along with the chaff.
Storing in a cool well-ventilated room in
tins, jars or ootton bags.
Tins, jars, cotton bags
No special staff required. The staff
recommended under "Extraction & Cleaning"
will do this work also.
Storing of seed is no problem, because the
storage period is only two or three months
in the dry season, when atmospheric humidity
is low. Room temperature in a well-
ventilated room averages 25 - 30C during
the storage period. Regular annual seed
crops and the fact that the seed stand area
is capable of producing, in a normal year,
at least seven times the annual require-
ment of seed precludes the need to carry
stocks from one year to the next.
None required
-164-
Appandii E
NETWORK ANALYSIS
A.I. PHASER
Forest Soienoe Consultant
Peniouik, Midlothian, U.K.
An afforestation project is composed of a great number of activities which are
spread over an extensive tract of land and involve a large number of people. Because of
the influence of seasonal factors, many of the activities which must be carried out to
complete the project are highly dependant on correct timing.
Given unlimited time and money, there would be no problem as work not done in one
season could be postponed until the next, and activities dependent on the completion of
other tasks could be delayed until the first tasks were finished. In practice, there axe
strict time and monetary limits, and the project manager is faced with a complex problem
of scheduling and controlling all the activities so that the whole programme of work
needed to complete the project is carried out within the time and money limits that have
been set.
This problem is common to managers of all business enterprises, so that in recent
years a number of techniques have been developed and their use expanded for dealing with
such scheduling problems. One of the best techniques for controlling and scheduling
complex operations is network analysis, which is concerned with optimising the performance
of a complete system such as an annual planting programme or all the operations involved
in the afforestation of a particular tract of land. It is not concerned with the task of
optimizing the physical effort involved in carrying out each of the activities which go to
make up the complete system. The latter is the concern of work study, which looks at the
individual routines, e.g. the best tools or methods of planting a tree.
from "A manual on the planning of man-made forests" FAD, Rome. Working Paper
IDtMI3C/73/22, 129 p. f 1973
-165-
The opportunity for saving time and money on large-scale projects by optimising
the logical sequence of event* is frequently very great* When operation* become more or
less routine | there is a tendency to think that few opportunities exist for further
improvement 9 but it is surprising how often it is possible to make up time after an
unexpected delay. This indicates that many operations could be speeded up f or by changing
the sequence in which they are performed, that it is possible to improve on the overall
performance of the system*
With complex tasks such as a large afforestation project it is too much to expect
that they can be completed on time without a constant watch on the progress of each of the
component activities. This watching of progress is virtually impossible without some
technique which enables the manager to condense the whole project to some simple form, and
represent the component parts graphically, so that all the interrelationships can be seen
at a glance*
Network analysis (sometimes referred to as programme evaluation and review
technique 9 PERT) is a graphical form of representing all the component parts and the
interrelationships of a complex operation - something like the orchestra conductor's
score*
The basis of network analysis is the representation of the component activities
and important events such as the start and finish of each activity in a graphic form in
the logical sequence in which they must take place* The convention used in most networks
ie to represent the events as circles, connected by arrows representing the activity thus:
Figure 1
The logical representation of a whole operation calls for the time to flow in one
direotion y so that the earliest activities are represented on the left, and later activities
axe put to their right* As each of the activities are incorporated, a network is built up
which shows from left to right the sequence in which they need to be performed* To fix the
position of any activity within the network it is only necessary to determine which
activities must precede it and which can run concurrently* Some operations can run
concurrently with others but cannot finish before them, so that it is particularly
important to determine which activities control the start and finish.
As a simple example of the construction and use of a net work f consider the activities
involved in planting an area of cleared land. The main activities involved are:
Activity Relative Time
A Mark out planting spots 8
B Dig planting holes 16
C Lift plants in nursery 4
D Transport plants to site 1
E Garry batch of plants from 1
transport to holes
-166-
AotivitT Relative Tine
F Plato* plants in holt 1
Fill holt* 4
H Apply fertilisers 4
Activities A 9 B and C oan all commence together, but A must finish before B.
D cannot start until is complete, and B oannot start until D is complete. F cannot
start until B and I are complete, while and H oannot start until F is complete.
and H must start together, but H oannot finish before Q. The relationship between these
activities therefore oan be represented as follows!
Figure 2
Q
3uoh a line graph of the activities enables checks of the logical sequence of the
activities to be made, and errors suoh as situations where the sequence in a closed loop
is reversed, or where activities are left dangling, in an open loop, can be eliminated.
Two basio rales which mast be followed ares
1) All events except the first and last must have at least one activity
entering and one activity leaving it.
2) All activities must start and finish with an event.
Having worked out the logical sequence as above, the next stage is to insert a
time scale in order to assess the overall performance of the network and the operation.
Assessing the tine required for each activity is net always easy. The most reliable
estimates are derived either from past records or from work studies, but in the absence
of these it is necessary to estimate the time. If possible, estimates should be made
oft
- the most optimistic time,
1 - the most likely time,
p - the most pessimistic time
and these should be weighted so that the average time is calculated byt
o + 4(1) + P
As far as possible, these estimates should be based on calculations of the time required,
taking into account the amount of physical work involved and the probability of outside
factors influencing the work, e.g. weather, sickness and economic factors. When the
probability cf an outside factor is not known, it is only necessary to estimate the most
-167-
likely time* The network omn thus be redraw with a tine soale and the duration of each
activity reoorded as in the following diagram:
Figure 3
16
10
Time
20
It is then possible to analyse the network in order to determines
1) The earliest time that an activity can start (TE) without
delaying the end of the project;
2) The latest time that an activity oan start (TL) without
delaying the end of the project; f
3) The critical path, which is the sequence of activities
which determine the minimum time in which the whole operation
oan be completed and is the longest path through the network;
4) The amount of float in each operation, which is the amount of
time in the parts of the network which do not lie on the
critical path by which the start and finish of the activities
oan vary without affeoting the overall time of the operation.
Aotivitv
A
B
C
D
E
P
a
H
TE
o
o
o
4
5
16
17
17
TL
8
10
14
15
16
17
17
Float
8
10
10
10
-168-
The table shorn that in this ainpla example tha oritioal path liaa along activities
B y P f Q and H because they hart sero float. Tha lark two take 4 days and atart on day 17 so
that the minimum time for completing the whole operation ia 21 days. There ia considerable
float available in the lifting of plants (o) and transporting (D and X) them. If it is
desirable to minimise the time between lifting and planting, then the lifting need not be
started until the latest time TL.
The less float an activity has the more oritioal it becomes. Following any path
through the network the oritioality of the path is inversely related to the amount of float ,
and the oritioal path is the one which needs the most attention by the manager in order to
ensure that the whole operation is not delayed.
One other important use of a network is for setting target dates. Supposing the
planting must be started or completed by a certain date, in order to avoid seasonal
influences, then all the activities before the oritioal activity can be located in time.
Thus if in the example, planting, activity F, must not start before, say, 1st April and be
finished by 16th Nay, with the relative times given in days, then* since event 5
represents the start of planting and event 6 represents the end of planting, these dates
can be substituted for the earliest time TE and the latest time TL, respectively, of the
events in Figure 3, and the others calculated accordingly.
Event Ho. Earliest Date Latest Date
1 16th March 2?th April
2 24th March 15th May
3 20th March 13th May
4 21st March 14th May
5 1st April 15th May
6 2nd April 16th May
7 6th April 20th May
8 6th April 20th May
Thus, the earliest date on which operations can start in order to be just ready to
plant on 1st April is 16th March, and the latest day for commencing operations in order to
have planting completed by 16th May is 2/th April.
A final us* of network analysis is in identifying those activities which can
prevent the whole operation from being completed within a target period. If the whole
operation used in the example above had to be completed within 18 days, then some
activities would finish up with negative float and the target would be impossible to
achieve. Under these circumstances it would be necessary to transfer resources (men) from
those operations with float to those with negative float* It is easy to see from the
simple example that the digging of planting holes has three days of negative slack when
the total operation time must be only 18 days* The float on the lifting of plants is
reduced from 10 days to 7 days, but there is still sufficient float there to suggest that
the lifting could take twice as long with half the number of men, thus releasing some for
digging holes. It is not always as straightforward as this because it could be that only
one man would be employed on lifting plants, but the general principle of searching the
activities with float for surplus resources oan make a useful contribution towards the
optimisation of the whole operation* If resources are reallocated in this way it is
necessary to rework the network in order to ensure that the logicality is maintained, and
to check for changes in the oritioal path*
Once a network has been draw and operations commence, it should not be put away in
a cupboard and f ergot t en | by continually updating it and referring to it as the work
proceeds, it is possible to identify in advance where new oritioal paths are emerging, and
therefore take steps in good time to reallocate resources in order to keep on target*
-169-
Appendiz F
MEDIUM-TERM FORECAST OF WORK
Operation
Unit of
Measurement
Year
1
Year
2
Year
3
Year
4
Year
5
Land survey-
ha
Nursery
ha
Plants
(1000)
Veg. clearance
ha
Ploughing
ha
Planting
ha
Fencing
km
Weeding
ha
Fertilizing
ha
Brashing/pruning
(1000)
Thinning
ha
Felling
ha
Road oonstr.
km
Road maint.
km
Miscellaneous
J/ adapted from Praser, AI M "A manual on the planning of man-made
forests", Rome, FAO. Working Paper FO*MISC/73/22, 129 p., 1973.
I
1
a
1
Q
S P
r*-
4
r-
to
s P :
ft x
*. .
m *- i
*~~
evi
in
r- CM
CO VO
8
vo
CO
**
I
CO
T
OO CM
m vo
vo
00
^
1i
*-
CM
in
r^ CM
*3
^
t^
00 VO
fH
vo
CO
9 .
-
1?
>->
g 1
*
M
c^ 8
in vo
t Vfl
CO t
in
X
^
to
GO CM
CO vo
^
VO
CO
^f
J
^
CM
JQ
r- CM
cq vo
o
VO
GO
^
*-
^
jn
SCM
vo
VO
co
T*
T-
I
*
s P :
I
3
o in
in T-
H}
vo t^-
rO f*}
m r-
*~
Total
nan-days
j a
'1
i:
61
3-8 8
CM t*- in
CM rO
i i
O CM
ft
1'
3
in in R
in in
|
x.
^ o 8
o m
i
cH
s
r
vo CM O
o ^
rH
|
H
i
<
e
H
5
1
8
i &
0. fc
! i !
S U S ^
2 X 3
1 i
S t
Total nan-days
Distribution o
a
I
K
)
8
H
1*
-171-
Appendix H
FLOW CHART OP COOT RECORDS
Day to Day
Labour attendance
and work record
Plant, vehicle
and machine log
Cost of materials and
minor equipment issued
Monthly
Monthly labour
summary of cost
Monthly
summary
machine
of cost
i
Monthly progress
report
Annually
Budgetary control
analysis
T
Annual summary of
operational cost
Future estimates
or budgets
i
Reconciliation with
expenditure
Allocation of
overheads
I
Cost studies or
cost analysis
-173-
QENERAL BIBLIOGRAPHY
Al'benskii and Nikitin, PD* (eds.). Handbook of afforestation and soil melioration*
1967 Translated from Russian in Jerusalem by Israel Program for Scientific
Translation. 516 p.
Allan , T.G, and Endean, F. Manual of plantatio.i techniques. Departmental in struct ion.
1966 Lusaka, Zambia, Forest Department.
Allan, T.Q. Handbook of plantation establishment techniques in the Nigerian savanna.
1977 Savanna Forestry Research Station, Nigeria. Rome, FAD. 64 p. Project
Working Document DPtNIR/7 3/007.
Balmer, W.E. f and Williston, H.L. Guide for planting southern pines. Atlanta, Georgia,
1974 U.S.A., USDA Forest Service, State and Private Forestry. 17 p.
Balmer, W.E., and Williston, H.L. Early considerations in pine management. Atlanta,
1975 U.S.A., Southerwestern Area State and Private Forestry. 8 p. Forest
Management Bulletin.
Binmore, A. An outline of problems arising in the replanting of clear felled Eucalyptus
1972 stands in Zambia. Paper for Seventh World Forestry Congress, Buenos Aires.
4 P
British Forestry Commission. Work study in forestry. Forestry Commission Bulletin No. 47.
1973
British Forestry Commission. Report on forest research. London, Her Majesty's Stationery
1976 Office.
Cozzo, D. Teohnologia de la forestaoion en Argentina y America Latina. Buenos Aires,
1976 Editorial Hemisferio Sur. 610 p.
Edlin, H.L. (ed.). Forestry practice. Eighth edition. London, Her Majesty's Stationery
1964 Office. 103 p. Forestry Commission Bulletin No. 14.
FA0 Essai de presentation uniform! see des conditions d' execution, des re suit ate
1974 et des oouts des reboisements. Rome, FAO. 199 p. FOiMISC/74/3.
FAD FAO World Symposium on Man-Made Forests and their Industrial Importance.
1967 Rome, FAO. 3 vols.
FAO Savanna afforestation in Africa. FAO, Rome. 312 p. FORtTF-RAF 95 (DEN).
1977
FAO Irrigation and Drainage Paper 24. Crop Water Requirement. FAO, Rome. 144p.
1977a.
Fielding, J.M. A handbook of methods for the establishment of pine plantations in West
1972 Malaysia. Pilot Plantations of Quick-Growing Industrial Tree Species,
Malaysia. Kuala Lumpur, UNDP/FAO. 44 p. TOtSF/MAL 12, Working Paper No. 20.
Flinta, C.M. Practioas de plantacion forestal en America Latina. Rome, FAO. 499 p. FAO
1960 Forestry Department Paper No. 15
Goor, A.Y. f and Barney, C.W. Forest tree planting in arid zones. Second Edition. New
1976 York, The Ronald Press Co. 504 P
Oroulez, J. Conversion planting in tropioal moist forests. Paper for Fourth Session of
1976 Committee on Forest Development in the Tropics. Rome, FAO. 22 p.
-174-
Oroulea, J., and Quillet, 0. Peuplements d 1 eucalyptus et de rlsineux tropioauz au Congo
^976 Brazzaville. Nogent-sur-Marne , France, Centra Technique Forestier Tropical.
140 p.
Haig, R.A. t and Soott, J.D. Mechanized silviculture in Canada* Paper for Seventh World
1972 Forestry Congress, Buenos Aires, 5 P
Proceedings of the Symposium on Stand Establishment* Wageningen y The
1974 Netherlands. 438 p.
Jacobs, M.R. Euoalypts for planting. Draft second edition, Rome, FAD. 398 p. FOsM ISC/76/ 10,
1976
Laurie, M.V, Tree planting praotioes in African savannas. Rome f FAO, 185 p, FAD Forestry
1974 Development Paper No, 19.
Letourneux f C. Tree planting praotioes in tropical Asia. Rome f FAO, 172 p. FAD Forestry
1957 Development Paper No, 11.
Levingston, R. Plantation management procedures for large-scale plantations in Penn insular
1973 Malaysia. Forestry and Forest Industries Development , Malaysia. Kuala
Lumpur, FAD. 205 p. FOtDP/MAL/7 2/009. Working Paper 36.
Marion, J, y and Poupon, J. Manuel pratique de reboisement. Institutde Reboisement,
1974 Tunisie. Rome, FAD, 345 P FOtSF/TUN 11 f Rapport technique 2.
Navarre Oarnioa, M. , and Molina Rodriguez, J,J, (oomps,), Tronic as de forestaoiSn, Madrid,
1975 Institute Naoional para la Conservaci6n de la Natural eaa (ICONA), 201 p,
Parry, M.S. Tree planting praotioes in tropical Africa. Rome, FAD. 297 p. FAD Forestry
1956 Development Paper No, 8.
Schubert, Q.H. et al. Artificial reforestation praotioes for the Southwest. Washington,
1970 B.C., U.S. Government Printing Office. 25 p* Agricultural Handbook No. 370.
Schubert, Q.H. , and Adams, R.3. Reforestation practices for conifers in California,
1971 Sacramento, U.S.A., Division of Forestry, State of California. 359 P*
Smith, D.M, The practice of silviculture. Seventh edition. New York, John Wiley and
1962 Sone, Inc, 578 p,
Suri, P,N., and Seth, S,K. Tree planting praotioes in temperate Asias Burma, India and
1959 Pakistan. Rome, FAO, 150 pp. FAO Forestry Development Paper No, 14.
USDA Forest Service, Intensive plantation oulturet five years research, St. Paul, U.S.A.,
1976 North Central Forest Brperiment Station. 117 P* General Technical Report NC-21,
USDA Forest Service, Proceedings of Symposium on Management of Young Pines. Atlanta,
1974 U.S.A., Southereastern Area State and Private Forestry. 349 p,
USDA Forest Service* Proceedings of the Symposium on Intensive Culture of Northern Forest
1977 TyPa Upper Darby, U,S.A. f Northeastern Forest Experiment Station, 356 p.
USDA Forest Service General Technical Report NE-29,
Wahlenberg, W,Q, (ed.). A guide to loblolly and slash pine plantation management in south-
eastern U,S,A, Mac on, U,S,A, , Georgia Forest Research Council, 360 p,
Report No. 14,
-175-
Wakeley f PC Planting the southern pines* Washington, D*C* f U.S. Government Printing
1954 Office. 233 P* Agriculture Homograph No* 18.
Weidelt f H.J. (compiler)* Manual on reforestation and erosion control for the Philippines*
1976 Esohborn, Germany, P.R. f German Agency for Technical Cooperation, 569 P
-177-
irora
Aoid pre-treatment of seed, 43-47
Acidity of soil, 111, 113
Aoromyrmex, 123
Actual evapotranspiration, 94-95
Aerial application
of fertilizers, 67
of fungicides, 123
of herbicides, 37, 71
of insecticides, 123
Aerial sowing, 44, 49 1 103
Agriculture
competition for irrigation water, 90, 96
improved "by afforestation, 100
pressure on land for, 8, 10
Agrisilviculture, 8
Agrosan, for treatment of tree wounds, 74
Aircraft
application of fertilizers from, 67
direct sowing from 44, 49 t 103
spraying of fungicides from, 123
spraying of herbicides from, 37, 71
spraying of insecticides from, 123
Air-pruning, 55
Aldrin (insecticide), 123-124
Aluminum powder (lubricant for seed pellets), 47
Ammate (herbicide), 35
Ammonium sulphamate (herbicide), 35
AMS (herbicide), 35
Angled blade, for mechanized clearing, 14, 17, 89
Animals, protection of plantations against, 8CV-82,
125-127
Annual programme of work. 136, 146
Anthroquinone (repellent), 47
Ants, control of, 123-124
Arasan (repellent), 47
Arboricides, 33 (see also Herbicides)
Arid sites (see also Irrigation of plantations),
afforestation techniques for, 88-89
general, 79-81
Arsenate (repellent), 47
Atrazine (herbicide), 36
Atta, 123
Augers, use in planting, 63
Balled plants, 54
Banquettes, 3,83
cost of construction in Tunisia, 84
Bare root plants, 54
Basin- list ing site preparation method, 86
Beating up, 65-66
Bedding, 29-30, 110 (see also Mounding)
Biological control of pests and diseases, 123
Bird repellents, 47
Bitumen application to drifting sand, 101-103
Boiling water pretreatment of seed, 45
Border irrigation, 92
Boron deficiency, 67
Broadcast sowing, 49
Broken contour line site preparation technique ,85
Browsing control, 125-127
Brush disposal, 8, 21-22
Bulldozers, use for land clearing, 17 f 97
Burning,
for pasture management, 80
.of synthetic industrial wastes, 113
of windrows and felled debris, 8, 22, 47
pre-planting, 3-4, 33, 47
post-planting, 129-130
Burning off, 3-4, 33, 47
Capillary fringe, 105
Cap tan (fungicide), 46
Care in planting, 53, 62-63
Care of plantations, 67-74
Care of planting stock, 54, 60
Catastrip (site preparation technique), 84
Ceratooystis ulmi t 122
Ceroospora pini-densiflorae, 123
Chaining (land clearing technique), 18-20
Chain saws for land clearing, 15
Charcoal, utilization of debris for, 8-9
Check dams, 86-87
Chemicals,
for disease and insect control, 123-125
for site preparation, 33-38
for weeding, 71
types,
fertilizers, 66-68, 111
fungicides, 33, 123, 125
herbicides, 33-38, 71
insecticides, 123-124
repellents and seed treatments, 45-4 7
Chloropicrin (use with methyl-bromide), 123
Choice of machinery,
for drainage, 109
for plantation establishment, 11, 23-24, 31
Choice of site, vii
Choice of species
for disease and insect resistance, 122
for mine spoils, 112, 114
general, vii, 137
Choppers (rolling drums), for land clearing, 15
Citemene (site preparation technique), 47
Citric acid, for breaking seed dormancy, 46
Clean cultivation, 27-29, 71, 80, 89
Clean weeding, 14, 27, 69-71, 89
Cleaning up of planting sites, 22
Clear felling, 4-5, 14-20, 89
Clearing land for planting,
chemical methods , 33-38
choice of method and equipment, 2-3, 12-13,
23-24
manual methods, 2-10
burning off, 3-4, 33, 47
clear felling, 4-5
debris disposal, 8
patch clearing, 3
release clearing, 5-7
strip clearing, 3, 5-6, 47-48
, stumping, 7 t 23
taungya, 8, 10
mechanized methods, 11-24
chaining, 18-20
chain saws, 15
-178-
choppers, 15
debris disposal, 21-22
principles, 11-14
root ploughing, 20, 88-89
scrub cutters, 15
shearing, 14
stump removal, 16, 20, 22
tractor techniques, multiple, 1&-20
tractor techniques , single, 16-18
tritters, 15-16
productivity, 23-24
Climber cutting, 150
Coiling of roots in containers, 53, 55
Collection of data for planning, 136-139
Collector drains, 106-107
Compartment register, 145
Compartment size, in plantations, 142
Competition for soil moisture, 1, 25 f 80, 88
Consumptive use of water, 90
Contact herbicides, 33
Container planting stock, 54-55, 58
deformation of roots, 53, 55
Contour banks, 88-89
Contour ditches, 3, 83-86
Contour steps, 83-86
coat of construction in Tunisia, 84
Contour strips, 3
Contour trenches, sowing in, 49
Contract labour, 4, 7
Controlled burning (see also Burning),
pre-planting, 3-4, 33, 47
post-planting, 129-130
Conversion planting, 5
Copper oxide, for breaking seed dormancy, 46
Costs,
clearing and site preparation, 10, 12, 84
erosion control, 84
irrigated plantations, 98
of direct seeding, 43
plantation, 84
recording of, 144-145 f 171
Crescent site preparation method, 86
Cronartium ribicola, 123
Crop coefficient, 94-95
Cultivation,
choice of method and equipment, 31
draught animals, 32, 71
manual, 25, 70-71
mechanized, 25-31, 70-71
bedding, 29-30, 110 (see also Mounding)
clean cultivation, 27-29, 71, 80, 89
pioneer ploughing, 27-28, 32
post-planting harrowing, 71-73
pre-planting harrowing, 25-31, 89
rid^e ploughing, 25-27
strip cultivation, 25-26, 70-71
subsoiling, 20, 25, 28-29 f 84 f 88-89, 108
turf ploughing, 25-27, 108, 110
post-planting, 68-73
pre-planting, 25-31
productivity, 31-32
Cut-off drains, 106
Cuttings, 56
Dalapon (herbicide), 36
Data collection for planning, 136-139
Debris disposal, 8, 21-22
Deep planting, 63
Deformation of roots in containers, 53 55
Density of roads in plantations, 142, 153-154
Density of stocking (see spacing)
Departmental taungya, 10
Desalination, 105
Development planning, 135
Dibbling,
for planting, 62
for direct sowing, 49-50
Dieldrin (insecticide), 123-124
piplodia pinea, 122
Direct planting, 3
Direct seeding,
advantages and disadvantages, 43-44 Y 53
methods, 49-51
of sand dunes, 103
timing of, 48
Direct taungya, 10
Disc harrowing, 28-30, 71-72, 89
Disc ploughing, 25-28, 89
Diseases protection against, 122-125
(see also names of diseases)
Distortion of roots in containers, 53 55
Distribution of planting stock, 60^-61
Ditching, for control of wild animals, 125-126
Dormancy, seed,
breaking of, 45-47
types of, 44-45
Dothistroma pini, 123, 125
Dowpon (herbicides), 36
Dragline excavators, 109
Drainage,
effect on spacing, 58
machinery, 108-170
of plantation sites, 25-26, 29-30, 103-111
of roads, 157
techniques, 105-108
Drains, type of, 106-107
Draught animals, 32, 71
Drill sowing, 49
Drip irrigation, 93
Dunes, 99-103
occurrence, 99-100
stabilization methods, 100-103
Effective rainfall, 94-95
Elements de banquettes, 85
Employment opportunities, 11, 138
Endogenous dormancy, 44
Bidothia parasitioa, 122
Ehdrin (repellent), 47
Enrichment planting, 5, 149-150
Erodible sites, afforestation of, 79-87
Erosion,
control, mechanical, 80-89
control, vegetative, 80-81
hazard, 1-4, 25, 28 f 38, 47
wind, 99, 115
Espacement (see spacing)
Establishment phase, definition, vii
Evaouator drains, 107
-179-
Evaluation of mining sites for planting, 114
Evapotranspirat ion ,
actual, 94-95
potential, 94-95
Excavators, for drainage, 109-110
Exogenous dormancy, 44
Fallow, 8
Farming for pay, 10
Felling (see Clearing land for planting)
Fencing,
for control of animals, 125-127
on sand dunes, 102
Fertilizers and fertilizing, 66-68, 111
Financial resources for planning, 138, 143-145
Fire, (see also Burning)
hazard of, 38, 81, 127-128
protection against, 80-81, 127-131
Firebreaks, 24-25, 128-129
Firewood, 8
Flood basin irrigation, 92
Flow capacities of irrigation channels, 97
Forecasting of work, 141-142, 169
Frill girdling, 6, 34-35 f 38 (see also Girdling)
Frost damage, 122
Frost heaving, 44, 57
Fungicides, 33, 123, 125
Fungus diseases, 123-125
Furrow irrigation, 92-93
Gezira (Sudan) irrigation project, 91
Giberellic acid, for breaking seed dormancy, 46
Girdling undesirable trees, 5-7 (see also
Frill girdling)
Gonipterus scutellatus, 123
Graded ditches, 85
Grading of planting stock, 5^-57
Gradoni, 3, 83
sowing of, 49
Gramoxone (herbicide), 36-37
Grazing, control of, 80-81, 127
Ground preparation (see site preparation)
Growth rates, 58
Gully control works, 86-87
Hardening off, 57
Hardpans and indurated payers, 25, 27, 29,
91, 108
Harrow, bedding, 29-30
Harrow plou#i, 27-28
pulverizing, 28
tine, 32
Harrowing,
post-planting, 71-73
pre-planting, 25-31, 89
Heath lands, ploughing of, 27
Hedges,
for control of animals, 125-127
for dune stabilization, 102
Heeling-in, 54, 60
Herbicides
definition, 33
for post-planting weed control, 71
for pre-planting weed control, 33-38
types,
animate, 35, 115
ammonium sulphamate, 35
AMS, 35
atrazine, 36
dalapon, 36
dowpon, 36
gramoxone, 36-37
paraquat, 36-37
pent achloro phenol, 35
picloram, 35
silvex, 34
simazine, 36
sodium arsenite, 6,35
sodium chlorate, 33-36
tordon, 35
triazines, 36, 2, 4-D, 35
2, 4, 5-T, 34
Hot water pretreatment of seeds, 45 1 47
Human resources, 138, 142-143
Hydrogen peroxide, for breaking aeed dormancy, 46
Incentives,
for afforestation, 81-82
for taungya, 10
Indolacetic acid, for treatment of tree wounds, 74
Industrial waste lands
preparation for afforestation, 114-115
types, 111-113
In-filling, 65-66
Inoculation with myoorrhizae, 68
Insect control, 122-124
Insecticides, 123-124
Institutional data for planning, 139
Irrigation of plantations,
economical aspects, 98
effect on tree spacing, 58
general considerations, 73, 9Q-92
methods, 92-93
planning and layout of, 96-98
water requirement of, 93-96
K.G. blade, 14, 17
Labour,
availability, 2, 12, 23
organization, 60
requirements, 170, 138, 142-143
vs mechanization, 2-3, 11-13, 23-24
Land,
clearing (see Clearing of land for planting)
hunger, as affecting taungya, 8, 10
levelling, 97, 112
resources for planning afforestation, 137
Land conditioner, for mechanized clearing, 15-16
Lanoline, for treatment of tree wounds, 74
Layout ,
of drains, 105-107
of irrigated plantations, 96-98
of plantations, 11, 24-25, 59, 142
of roads, 11, 98
-180-
L each ing,
of mine spoils, 113
of saline soils, 91, 105
Leaf cutting ants, 123-124
Levelling,
of land for irrigated plantations, 97
of strip mined areas, 112
Liming, 111
Line clearing, 5, 6, 9, 150
Line planting and line plantations, 5-6,
149-150
Line sowing, 49
Line weeding, 70-71
Livestock, protection against, 80-81, 127
Macro-nutrients, 66
Management, effect on spacing, 59
Management plans, 136-146
Manual methods of afforestation,
land clearing and site preparation, 2-12,
27, 70-71
planting, 84
weeding, 70-71
vs mechanical methods, 2-3, 11-13, 23-24
Maps for plantation planning and implementation,
137, 145, 152
Marking of planting lines, 59-60
Marshes, drainage of, 103-105
Mechanical control,
of erosion, 80-89
of pests and diseases, 123-124
Mechanized methods of afforestation,
defined, 11
land clearing and site preparation, 11-32
planting, 64-65, 84
weeding, 70^72
effect on spacing, 58
vs. manual methods, 2-3, 11-13, 23-24
Meth&de nteppicpe, 88-89
Methyl - "bromide (fumigant), 123
Micro-nutrients, 56
Mine spoils
choice of species, 114
economic considerations, 114-115
evaluation of the s. .e, 114
preparation for planting, 111-112, 114-115
Minipots, 55
Mixed plantations, 122-123
Monoohaetia union rni T 122
Mole plough and ploughing, 108-109
Mould-board plough,
for contour ploughing, 28
for drainage, 25-27, 108-109
for deep furrows, 89
Mounding, 29 (see also Bedding)
in saline marshes, 105
Mound sowing, 50
M til oh ing,
of arid lands, 88
of sand dunes, 101-103
of unstable slopes, 86
Myoorrhizaa, 68
Naked rooted stook, 54
Net irrigation water requirement, 93-96
Network analysis, 164-168
Nile Waters Agreement, 91
Nitrogen,
fertilizer, 66-68
fixation, 68
soil nutrient status, 66, 111
Notching technique for planting, 62
Nurse crops, 68
Nutrients,
deficiencies, 66, 111
effect on spacing, 58
individual chemical,
boron, 67
nitrogen, 66-68, 111
phosphorous, 66-68, 111
potassium, 66, 111
use by taungya crops, 10
Operational data for planning, 139 (see also
Productivity rates and work norms)
Operational planning, 135-146
Paraquat (herbicide), 36-37
Patch clearing, 3
Peat bogs, preparation for afforestation,
25, 103-111
Pegging of planting lines, 59-60
Pelleting of seed, 47
Pent achloro phenol (herbicide), 35
Percolation, 80-81
Phoracantha a e mi pun c tat a, 124
Phosphorous,
fertilizer, 66-68
soil nutrient status, 66, 111
Physiological condition of planting stock, 56
Phytocides, 32 (see also Herbicides)
Picloram (herbicide), 35
Pioneer ploughing, 27-28, 32
Pit planting, 11, 25, 62-63
Planning,
de ve lo pment , 135
national, 135
network analysis, 139, 164-168
of plantations, 135-146
irrigated, 96
of roads, 151-152
of seed collection and handling, 161-163
operational, 135-146
periodic, 139
plantation management, 135-H6
seotorial, 135
Plans,
plantation management, 139-146
skeleton, 136
Plantations,
clearing and preparation of site, 1-38
coats, 84
fertilization, 66-68, 111
irrigation, 58, 73, 90-98
layout, 11, 24-25, 59, H2
planning, 135-146
-181-
p rot action against,
animals, 80-82, 125-12?
disease, 122-125
fire, 80-81, 127-131
grazing, 80-82, 127
insects, 122-124
man, 80-82, 127
weather, 121-122
pruning, 58-59 , 74
spacing, 11, 58-59, 88, 149
taungya, 8, 10, 51, 59t 71
tending, 68-74
weeding, 69-73
Planting,
advantages and disadvantages vs. direct
sowing, 43-44 f 53
care, 53- 62-63
costs, 84
enrichment, 5, 149-150
line, 5-6, 149-150
machines, 64-65
methods,
manual , 62-63
mechanized, 64-65
principles, 53-60
organization of, 60
replacement of casualities, 65-66
season and timing of, 57-5$! 6*0
stock
balled root, 54
bare root, 54
care of, 54,60
cuttings, 56
grading of, 56-57
physiological condition of, $6
plugs, 55
potted, 54-55
resources, 137
rooted cuttings, 56
sets, 56
size, 55-57
striplings, 54
stumps, 56, 102
transport, 54, 61
tubed, 55
wildlings, 54
Ploughing and discing, 25-29, 89
of firebreaks, 25, 128
pioneer, 27-28, 32
productivity, 31
ridge, 25-27
strip, 25-26
with draught animals, 32
Ploughs,
disc, 25-27, 89
harrow, 27-28
mould-board, 25-28, 89, 10&-109
root, 20, 88-89
tine, 27-28
Plugs (planting stock), 55
Poison baits, 126
Poisoning undesirable trees, 5-6, 34-35t 38,150
Polythene containers for planting stock, 55
Potassium,
fertilizer, 66
soil nutrient status, 66, 111
Potassium nitrate, for breaking seed dormancy, 46
Potential evapo transpiration, 94-95
Potets, 3
Pots (see Polythene containers for planting stock)
Pre-ohilling, 46
Pre-planting harrowing, 25-31, 89
productivity, 31
Prescribed burning (see Controlled burning)
Pressure on land for agriculture, 8, 10
Pretreatment of seed, 44-47
acid, 45-47
scarification, 45, 47
stratification, 4M7
water, 45, 47
Productivity rates and work norms,
manual ,
banquettes, 84
brushing and felling, 4
clearing, 84
contour steps, 84
felling and burning, 4
line clearing, 6
line sowing, 49
piling debris, 23
planting, 84
production of planting stock, 84
replacement of casualities, 84
roads, 84
stumping, 7, 23
tending, 84
weeding, 70
mechanical,
banquettes, 84
chaining, 23
choppers, 15
clearing, 23, 84
line sowing, 49
ploughing, 31
pre-planting harrowing, 31
replacement of casualties, 84
roads, 84
subsoil ing, 84
tending, 84
tritters, 15
windrowing, 23
Protection of plantations against
animals, 80-82, 125-127
diseases, 122-125
fire, 80-81, 127-131
grazing, 80u82, 127
insects, 122-124
man, 80-82, 127
weather, 121-122
Protection of planting stock against
termites, 63, 123-124
wind, 63, 89
Pruning, 58-59, 74
Pulverizing harrows, 28
Pumps for irrigation, 98
Pusher bar, use with crawler tractors, 16
-182-
Rabbit control, 126
Rab method, 47
Rainfall,
build-up in soil before planting, 57
intensity, 79-81
seasonal distribution, 79-30
Rakes, tractor, for clearing and windrowing,
16-17, 21-22
Rasettes, 89 (see also Subsoil ing)
Ravine control, 86-87
Recording of costs, 144-145, 171
Release clearing, 5-7
Removal of containers before planting, 55 63
Repellents,
on plants, 126
on seed, 47
Replacement planting, 6566
Replacement sowing, 51
Reporting of plantation activities, 144-145, 171
Resource data, for planning, 137-138
Rhizoctol oombi, for seed pelleting, 47
Ridge ploughing, 25-27
Ridges, tied,
construction of, 47, 86
sowing of, 47, 49
Ring-barking, 5-7 (see also Prill girdling)
Ripping (see Subs oil ing)
Roads, 24-25, 151-158
classes, 152-153
cost of construction in Tunisia, 84
density, 142, 153-154
indexing, 152
layout , 1 1
in irrigated plantations, 98
maps, 152
planning, 11, 142, 151-152
standards of construction, 154-158
Root distortion in containers, 53, 55
Root ploughs, 20, 88-89
Root-shoot,
cuttings, 56, 102
ratios, 56
Rooted cuttings, 56
Rotavators, 25, 28, 71
Saccardy's formula, 83
Saline soils, afforestation of, 91, 96, 105
Salinity problems in irrigated plantations, 91, 93
Salt marshes, 105
Salt spray, 121-122
Sand dunes,
occurance, 99-100
stabilization of, 100^103
Scale of operation, 13, 24
Scarification of seed, 45, 47
Scrub cutters for land clearing, 15
Season, planting 57-58, 60
Seed,
availability, 43-44, 53, 137
collection, planning of, 161-163
cost, 43
direct seeding of,
advantages and disadvantages, 43-44, 53
methods, 49-51
of sand dunes, 103
timing of, 48
dormancy, 44-47
pelleting of, 47
pre treatment of, 44-47
scarification, 45, 47
stratification, 46-47
Seedlings (see Planting stock)
Selidosema suavis, 122
Sequence of plantation operations, 32
Sets (as planting stock), 56
Shamba, 8, 10 (see also Taungya)
Shaping, 74
Shearing, 14
Shelterbelts, 101
Shelterwood, 6
Shifting cultivation, 8, 10, 81
Shooting wild animals, 126
Si 1 vex (herbicide), 34
Silvicide, 33 (see also herbicides)
Silvicultural control, 123
Simazine (herbicide), 36
Site,
choice for planting, vii
evaluation of industrial waste lands, 114
preparation,
burning, 3-4, 33, 47
clear felling, 4-5, 14-20, 89
chemical, 33-38
citemene, 47
contour ditches and steps, 3, 83-86
drainage, 25-26, 29-30, 58, 103-111
for direct sowing, 47-48
for irrigated plantations, 97
levelling, 97, 112
manual methods, 2-12, 27
mechanical methods, 1132
objectives, 2
patch clearing, 3
strip felling, 3, 5-6, 47-48
stumping, 7, 16, 20, 22, 23
terracing, 82-86
tie ridging, 47, 86
Size and grading of plants, 55-57
Skeleton plan, 136
Slash disposal, 8, 21-22
Sodium arsenite (herbicide^, 6, 35
Sodium chlorate (herbicide;, 33, 36
Soil,
conservation works, 80-89
degradation, 1, 8, 80
disturbance, 13, 16, 21
erosion,
control, mechanical, 80-89
control, vegetative, 8O-81
hazard, 1-4, 25, 28, 38, 47
wind, 99, 115
hardpans, 25, 27, 29, 91, 108
importation to planting sites, 112, 114
moisture, 25, 58, 81
build-up before planting, 57
storage capacity, 94-95
nutrients, 58, 66, 111
reaction, 111, 113
retaining structures, 80-69
texture, effeot on irrigation methods, 93
water holding capacity, 91
Soil acting herbicides, 33, 36
-183-
Sowing, direct
advantages and disadvantage!, 43-44, 53
methods, 49-51
of sand dunes, 103
timing of, 48
Spacing,
in plantations, 11, 58-59
in relation to soil moisture availability, 88
of irrigation furrows, 93
in line enrichment plantings, 149
of roads, 153-154
Species, choice of,
for disease and insect resistance, 122
for mine spoils, 112, 114
general, vii, 137
Spoi] sites (see Mine spoils)
Spot sowing, 49-5 1 , 71
Spot weeding, 70-71
St ab 1 1 1 zat ion ,
of mine tips, 1 12
of sarid dunes, 100-103
Stinger, for mechanized clearing, 18-19
Storage capacity of soil, 94-95
Stratification of seed, 46-47
Strip clearing, 3, 5-6, 47-48
Strip cultivation, 25-26, 70-71
Strip mines, 111-112 (aee also Mine spoils)
Striplings, 54
Strips contour, 3
Stumping,
manual, 7
mechanical, 16, 20, 22
work norms, 23
Stumps (as planting stock) 56, 102
Subsoil ing, 20, 25, 28-29, 108
along contour banks, 88-89
coats in Tunisia, 84
meth&de steppicrue, 88-89
of catastrips, 84
Subsoil ing plough, 28
Sulphuric acid, for pre-treatment of seed, 45
Surface irrigation, 92-93
Swampland,
drainage, 105-111
occurrence, 103-105
Taungya, 8, 10, 51, 71
effect on spacing, 59
Tartaric acid, for breaking seed dormancy, 46
Tending of plantations
irrigation, 73, 90-98
pruning, 58-59, 74
shaping, 74
thinning, 59, 123, 149-150
weeding, 68-73
Termites, 63, 123-124
Terracing, 82
Thinning, 59, 123
of line enrichment plantations, 149-15
Tied ridges,
construction of, 47, 86
sowing of, 47, 49
Timing and timeliness,
of direct sowing, 48
of planting, 13, 31-32, 57-58, 150
Tins harrows, 32
Tins ploughs, 27-28
Tordon (hsrbioids), 35
Torrao paulista, 55
Torrsnt control, 86-87
Total herbicides, 33, 36
Training of labour, 12, 32, 138, 143
Translocated herbicides, 33-36
Transport of planting stock, 54, 61
Trapping wild animals, 126
Trap trees, 124
Triazines (herbicides), 36
Tritters, 15-16
Tubes, as plant containers, 55
Turf p lough ing, 25-26, 108, 110
Ultra low volume spraying, 37, 71
Underp Ian ting, 5-7
Varying grade contour ditches, 85
V-blade, for mechanized clearing, 14
Vegetative propagation, 53
Village forestry, 82
Water
conservation methods, 80-89
holding capacity, 91
pre-treatment of seed, 45-47
quality, 91-96
requirements, 90, 93-96
retaining capacity, 80
retaining structures, 80-87
storage reservoirs, 81
Watering plantations, 73 (see also Irrigation
of plantations)
Waterlogged sites,
drainage, 105-111
in irrigation schemes, 91 t 93, 95
occurrence, 103-105
Wattle fencing, 102
Weeding, 69-73
by burning, 129-130
chemical, 71
clean, 14, 27, 69-71, 89
of irrigated plantations, 73
regimes, 73
Weed,
competition, 53, 58
elimination, 70-73
suppre s s ion , 70
Wet sites (set. Waterlogged sites)
Wicker work fences, 86
Wildlings, 54
Wind,
damage, 57, 63, 89, 104, 121
erosion, 99
Windbreaks, 101-102
Windrowing of debris, 8 f 21-23
Work norms (see Productivity ratss and work norms)
Work study, 164
Yugoslavia, 81
Zino fertilizers, 68
Zinc oxide, for breaking seed dormancy, 46
-182-
