Historic, Archive Document

Do not assume content reflects current
scientific knowledge, policies, or practices.

September 1988

A report for land managers on
recent developments in forestry
research at the four western
Experiment Stations of the Forest
Service, U.S. Department of
Agriculture.

F®gt§s^

In This Issue

page

Alarming Armillaria : a
problem in the Inland
West 1

Preparing to harvest
second-growth timber 6

Where deer and cattle

roam 1 0

Help for determining

carrying capacity 17

New from Research 20

Cover

Even decades ago, resource
specialists were concerned about
deteriorating rangeland conditions
in the southwest. This 1916 photo
shows a study underway on the
Jornada Experimental Range in
southern New Mexico. Today,
many ranges in this region
continue to be overgrazed and
remain in poor condition. Scientists
at the Rocky Mountain Station
have developed a guidebook to
help ranchers and land managers
estimate livestock carrying capa¬
cities for these fragile grasslands.
Details begin on page 17.

To Order
Publications

Single copies of publications
referred to in this magazine are
available without charge from the
issuing station unless another
source is indicated. See page 27
for ordering cards.

Each station compiles periodic
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Permission to reprint articles is not
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given to the Forest Service,
U.S.D.A.

Mention of commercial products is
for information only. No endorse¬
ment by the U.S.D.A. is implied.

Western Forest
Experiment Stations

Pacific Northwest Research Station
(PNW)

P.O. Box 3890
Portland, Oregon 97208

Pacific Southwest Research
Station (PSW)

P.O. Box 245
Berkeley, California 94701

Intermountain Research
Station (I NT)

324 25th Street
Ogden, Utah 84401

Rocky Mountain Forest and
Range Experiment Station (RM)

240 West Prospect Street

Fort Collins, Colorado 80526-2098

D

by Elizabeth Close
Intermountain Station

Alarming
Arm Maria: a
Droblem in the
nland West

Casual visitors to the woods are
usually focused on the tree
canopy overhead— few of them
think about the forest teeming
under their tennis shoes. But re¬
source managers recognize the
soil as a lively and important part
of the forest ecosystem. They
know the soil is not only impor¬
tant, but critical in determining
what vegetation any site supports.
And the soil most attracts their at¬
tention when a site goes “bad”—
when a once highly productive
site slips to one yielding only a
marginal crop of trees.

Researchers at the Intermountain
Research Station’s Forestry Sci¬
ences Laboratory in Moscow,

Idaho are "digging in the dirt” to
learn more about the relationship
of forest soil to forest productivity.
Since the early 1 980’s, a project
headed by Plant Pathologist Al
Harvey has learned much about
soil components and inhabitants,
and about how forest manage¬
ment practices can help or harm
future soil site productivity. The
project’s research emphasizes the
importance of organic materials—
decaying plant debris and woody
residues— as soil components sup¬
plying storehouses of nutrients
and moisture for new plant
growth. Organic materials also
provide environment and energy
for many microorganisms critical
to both the nutritional quality of
forest soils, and the ability of some
trees to extract nutrients and
moisture from the soil.

Plant Pathologist Neil Martin examines
Armillaria fruiting bodies in the forest.

An example of important and
beneficial soil microorganisms is
wood decay fungi, which help to
sustain certain conifer rooting,
nitrogen input, nutrient storage,
and recycling capabilities. But
other soil inhabitants can be a bit
overzealous in the drive to break
down and recycle organic mater¬
ial. Armillaria spp., or shoestring
root rot fungus, has the capability
to "recycle"— that is, "kill”— the
root systems of living trees. And
once a tree’s roots are gone, it
soon starves, falling to the ground
where other soil-bound nutrient
recyclers feast on the now
reachable wood fiber.

A world-wide problem

“Armillaria, in some form or
another, occurs world-wide,” says
Harvey. “It has a broad host
range, and affects a large percent¬
age of the world’s woody plants.
We will never get rid of it, but we
don’t really want to. Armillaria is
as much a part of the natural
forest ecosystem as trees, often
existing peaceably and causing
no harm. But when it gets "turned
on,” in a pathogenic sense, it can
damage an existing stand and
stay in the soil to inhibit following
generations."

Harvey stresses the seriousness of
the Inland West’s root rot prob¬
lem, "What we have in northern
Idaho is a full-blown epidemic. Ar¬
millaria infection is on the rise, and
causing extensive damage— esti¬
mates of 50 percent loss of site
productivity may be conservative
in some areas. There is potential
to lose even more. This may seem
like a pessimistic view, but where
do you draw the line between
pessimism and realism— you can’t
realistically ignore this problem
and have it go away.”

" Armillaria is a very effective nutri¬
ent recycler. We just need to keep
it from recycling things that we
don’t want recycled yet— like the
roots of living trees.”

1

So what causes Armillaria to get
pathogenically “turned on"? The
project’s scientists are investi¬
gating a web of relationships be¬
tween host, pathogen, and envi¬
ronment that seems, at times, to
uncover as many questions as
answers. In the "outdoor lab" of
the Inland West, they are well
situated to work at untangling
that web.

The outdoor lab

The Inland West represents an ex¬
tended edge between the crest of
the Cascades to the west, and the
crest of the Rockies to the east.
“What we have is a coast-type
forest in a more continental
climate," Harvey said. "Ecosys¬
tems to the west are better buf¬
fered, with more moderate climate
and better quality soils. When
species like grand fir, Douglas-fir
and western hemlock grow in the
Inland West, they are pushed to
the limits of their range, and lack
the built-in resistance they seem to
exhibit in western Oregon and
Washington. And, while resource
managers like to have these
species— they regenerate well and
can have high market value— their
susceptibility to Armillaria in this
region often makes them chancy
choices.”

Project scientists have shown pine
and larch to be more root rot-
tolerant. "But we really don’t know
why Armillaria hits some species
harder than others,” said Harvey,
"or why it infects individual trees
in a stand, leaving others of the
same species untouched. We
have found a connection between
the condition of a stand, its habitat
type, and its susceptibility to root
rot attack— when trees get sick,
Armillaria often moves in. It is
definitely a problem of stressed
trees and poor sites."

Armillaria fruiting bodies— outward signs of
the underground threat to woody plants .

Forester Jonalea Tonn is working
on uncovering interactions be¬
tween growth of certain white
pines and susceptibility to Armil-
laria damage. "We need to be
able to define a ‘poor site,’ and it
may not only be in terms of pro¬
ductivity,” she said. "We need to
grow forests that are more
healthy, and find ways to block
Armillaria' s path. And, since Armil¬
laria’ s path is through the soil, we
can go a long way toward proper¬
ly managing root rot by properly
managing soil.”

2

Armillaria' s pathogenic path is
aided by activities that cause
change. For example, it is often
given a boost when trees are har¬
vested. After the stems are re¬
moved, Armillaria seizes the
chance to occupy tree roots left in
the soil. When regeneration is at¬
tempted, the pathogen transfers
onto the roots of the seedlings.

According to Harvey, areas with
historic patterns of disturbance
show an increased rate of attack.
“We have sites in northern Idaho,
for example, on the Idaho Pan¬
handle National Forests’ Fernan
Ranger District around Coeur
d’Alene, where productive but
marginal soils have been logged
for over 100 years, he said. “Log¬
ging practices typically took the
‘biggest and the best’, depleting
stands of their stronger, more
tolerant trees, and extensively
disturbing the soil. Now the Armil¬
laria has such a strong hold that it
is difficult to get susceptible trees
to mature there.”

The root rot capital

Wes Kellie, Forest Silviculturist for
the Idaho Panhandle National For¬
ests, smiles when asked about the
designation of the Fernan Ranger
District as, “the root rot capital of
the world." “Yes, I've heard it
called that,” he admits, “but we're
aggressively working to change
that title. We now know that we
created a bad situation in the

1970’s, when we used partial cut
systems rather extensively to re¬
place clearcutting. Partial cutting
strategies on the Fernan District
resulted in big problems— Armil¬
laria stayed with or moved into the
trees that were left and spread to
the young trees that were planted.
Now on sites with major root rot
problems, we’ll most likely clear-
cut, prescribe burn and plant
more Armillaria- tolerant species.”

The relationship of Armillaria to fire
is also under scrutiny. Fire
histories show that cyclic fire was
a natural feature in northern Idaho
forests. After a moderate buildup
of fuels, fire would move through
an area at temperatures that did
minimal soil damage. But since
forest management introduced fire
control, these areas burn less fre¬
quently, creating a greater buildup
of fuels. Now when these sites do
burn, they burn with much higher
temperatures that cause greater
degradation of the soil. Fire sup¬
pression can also retard nutrient
recycling and increase stocking
densities, improving conditions for
root rot outbreaks.

Armillaria' s relationship to other
forest pests may also uncover
clues to its habits and control.
Scientists have noticed some coin¬
cidence of the pathogenic fungus
with bark beetle infestations, but
the relationship is not well estab¬
lished. It may be that both pests
pick on the same unthrifty trees
for the same reasons, or that site
conditions are simultaneously

attractive to both. But another
microbial organism may have a
helpful role as a biological control
agent. Trichoderma, or sugar
fungus, is a general soil inhabitant
that also does well after fire, as
germination of its spores is stimu¬
lated by heat and smoke. Tricho¬
derma competes with Armillaria by
capturing the substrate that Ar¬
millaria typically occupies, causing
it to cease or reduce its produc¬
tion of inoculum.

Extending the models

Involvement with the root rot
problem has extended to other
Intermountain Research Station
projects and to several other
research projects throughout the
West. A recent meeting of Inter¬
mountain Station scientists laid the
foundation for a coordinated,
Station-wide Armillaria research
program. And a West-wide root
rot model, which simulates the ac¬
tion of Armillaria in a stand, has
been developed as an extension
of the Prognosis Model for Stand
Development (see Forestry Re¬
search West , August 1987). The
root rot extension was developed
with the cooperation of specialists
from universities, Forest Service
research, National Forest timber
and forest pest management
groups, and the British Columbia
Forest Service. All these partici¬
pants supplied the information
and/or inventory linkages needed
to base the model on actual
conditions.

3

Surrounded by petri dishes, Plant Pathol¬
ogist Gerald McDonals shows the growth
of Armillaria isolates.

“We linked the inventory of root-
diseased stands to a proposed
forest inventory system,’’ said
Mensurationist and Prognosis
Project Leader Al Stage. “From
an inventory of infected trees, we
can use the pathologists’ knowl¬
edge of how root rot works to
predict infection of trees nearby.
The model incorporates the toler¬
ance of the species, site condi¬
tions, and other factors. But the
model works as if Armillaria
spreads, when instead what may
be occurring is an ever-present
form turning pathogenic. We really
aren't sure how it happens. But in
the meantime, the model works—
it seems to represent the way
Armillaria damage occurs. It may
be right for the wrong reasons.”

Incompatible and compatible parings of
single basidiospore isolates of Armillaria
spp

Harvey stresses that one benefit of
the model was getting key people
together to participate in its devel¬
opment. “We had to deal with two
major opinions of how the fungus
behaves," he said. “But working
together, we designed the model
so it can accommodate both."

“We can use the model to predict
the probability of infection and the
eventual time of death, as well as
what will happen with different
stand treatments," Harvey said.
“We can better identify areas that
are getting into trouble before the
major losses of productivity to
Armillaria occur."

Other models, developed at the
University of Montana and the
Intermountain Research Station's

Intermountain Fire Sciences Labor¬
atory in Missoula, are being
adapted for use in Armillaria re¬
search. MT-CLIM provides daily
microclimate conditions to a phys¬
iological process model called
DAYTRANS, and to a nutrient
recycling model called FORTNITE
which keeps track of nitrogen.
“With this combination we can
more truly emulate how trees
grow under different conditions,”
said Plant Pathologist Geral
McDonald. “We can look at a
number of physiological traits that
will help assess stand health, and
develop the characteristics of a
more resistant population. Maybe
the health of the stand instead of
the genetic makeup is the most
important feature in root rot
resistance.”

“We’re just now realizing the
potential damage Armillaria can
cause," McDonald said, “because
we thought we knew more about
it that we do. We need to frame
our knowledge of ecosystem pat¬
terns and responses with broad-
based ecological and physiologi¬
cal process models. What we’re
learning can be extended through
models, as we influence the
models to influence
management.”

The study ot host-pathogen-envi¬
ronment relationships will yield
many methods for decreasing the
loss of forest productivity to Armil¬
laria in the Inland West. But
another major part of the research
project is devoted to studying the
characteristics of the microbial
organism itself. Plant Pathologist
Geral McDonald also concentrates
on that.

4

Sorting out the species

“The taxonomy of Armillaria as an
organism is not well known,’’ said
McDonald. “It was as recently as
the late 1970’s that the fungus
was thought to be a single
species instead of a large collec¬
tion of species. Nine species have
been identified in North America,
but there is some dispute among
‘armillariologists’ about the classifi¬
cation. We have isolated four
species here in the Inland West,
and believe two of these are caus¬
ing most of the damage, but there
may be massive amounts of varia¬
tion even within these species. We
don't know if the species segre¬
gate by host, or why some hosts
are more tolerant than others. And
do Armillaria species get “turned
on’’ in different ways? Do condi¬
tions at the time of site disturb¬
ance dictate which species takes
off? And are there weaknesses of
the organism that we can better
exploit for control? We’ll really
help resource managers when we
come up with some of these
answers.”

One of McDonald’s experiments
involves collecting and identifying
samples of Armillaria mycelium
from many different sites, habitats,
and hosts. He places two of the
carefully catalogued isolates side-
by-side on growth medium in a
petri dish, charting their form and
interaction. Thousands of petri
dishes surround McDonald in the
lab as he explains the results.

“The interaction of the two isolates
as they grow tells whether or not
they are compatible or incompat¬
ible,” McDonald said. “If they are
compatible, they are from the
same genotype; if incompatible,
they are from dissimilar geno¬
types. And, since we know the
site, habitat, and host origin of
each sample, we can begin to
characterize which clones and
species do well in which locality,
or under what conditions.”

“We can also challenge collected
samples by growing them with
known taxonomic isolates,”
McDonald said, "and thereby
expanding our work in species
identification and classification.”

Plant Pathologist Neil Martin is
involved in another aspect of
Armillaria study. “Taxonomy of the
species is based on the sexual
form, or fruiting body of the or¬
ganism,” Martin said. "Producing
fruiting bodies in the lab is an im¬
portant step in species identifica¬
tion and understanding.”

In the forest, Armillaria sends up
fruiting bodies in the fall. Martin
places pieces of the inoculum on
growth medium in glass bottles,
then simulates the temperature
and light regimes typical of that
season.

Martin also investigates the role of
spores in Armillaria propagation.
“We know that the organism
spreads through the soil, and
suspect that this is its major
means of perpetuation. Repro¬
duction through spores is not
generally recognized as a major

problem. . .yet,” he says. And his
fascination with the organism is
apparent when he talks about
another unsolved mystery.

‘‘Armillaria glows— it gives off a
soft blue light that is both ob¬
servable and measurable,” says
Martin. This certainly requires an
expenditure of energy. But why
would a subterranean organism
retain a light-emitting feature?
Maybe to attract beetles. One can
only speculate— we really have no
idea why it sits down there in the
dark and glows.”

Harvey emphasizes the need to
better understand what goes on
“down there in the dark.” “Our
understanding of below-ground
ecosystems is rudimentary at
best,” he said. “We need more
expertise in the contributions of
soil to growing healthy trees.

Forest managers are eager for
answers. Today's managers are
receptive— they are better schooled
in pathology and pest manage¬
ment than their predecessors, and
look further at why things aren’t
working, at why the cut can’t be
sustained. They are willing to look
beyond the sales aspect of a
stand to the biological aspect of
the entire system. And that will
make the difference in successful
management of forest ecosystems,
both above and below the
ground.”

For more information on this
research, contact Al Harvey,
Forestry Sciences Laboratory,

1221 South Main St., Moscow,
Idaho 83843, (208) 882-3557.

5

Preparing
to harvest
second-growth
timber

by Dorothy Bergstrom
Pacific Northwest Station

In anticipation of the time when
second-growth trees will be the
primary source of timber in the
western United States, researchers
at the Pacific Northwest Station
are searching for answers to ques¬
tions that forest managers have
already begun to ask about
changes that second-growth har¬
vesting will bring. Some of these
questions arise primarily because
new equipment and technology
will be needed to harvest younger
and smaller trees. Other questions
are prompted by current trends in
the economics of forest manage¬
ment and the need to better
understand the relation between
timber harvest and forest
productivity.

One trend is toward greater utiliza¬
tion of wood to meet an increased
demand for products. Compli¬
cating the situation is the fact that
wood from second-growth trees
may not be as dense or strong as
that in old-growth trees, and often
produces lumber or plywood with
more knots and different drying
characteristics. Likewise, there is a
growing awareness of the relation
between harvest levels and envi¬
ronmental considerations, such as
air pollution and site productivity.
Removing too much biomass may
slow the growth of future forests
and cause some loss of wildlife
habitat, whereas an excessive
amount of material left in the forest
can impede wildlife movement
and management activities.

As the harvest of second-growth
timber increases, a new set of
questions arises. According to Jim
Howard, leader of the Biomass
and Energy research unit, "Every¬
thing changes when we have the
capability to snip off smaller trees
at the ground, pick them up and
move them intact. This capability
marks a drastic departure from
harvesting old growth trees and
adds new requirements and op¬
portunities for forest managers.”

It is now possible to move whole
trees to an inwoods processing
site, where machines can debark,
delimb, and process them for
multiple products— logs, chips,
and hog fuel (tops and limbs
burned for energy)— that can be
trucked from the forest. This capa¬
bility requires changes in methods
for appraising, selling, and har¬
vesting timber. Three primary
characteristics of second-growth

Specialized equipment for delimbing,
debarking, chipping, and making hog fuel,
makes whole-tree processing possible on a
small landing.

trees are responsible for the
changes: (1) smaller trees will
generally have more knots but
less defect and thus less break¬
age and cull during harvest; (2)
smaller, more uniform trees and
stands present greater opportuni¬
ties for harvesting and utilizing en¬
tire trees; and (3) less timber vol¬
ume per acre will make the use of
economically efficient harvest
methods more important. Where
the terrain is not too steep, har¬
vesting will be mechanized, with
more of each tree ultimately
leaving the forest.

6

One new requirement is for ways
to measure volume and weight of
trees. The board-foot measure that
was appropriate when most of the
old-growth trees were converted
to lumber is not relevant to the
wider variety of products made
from smaller trees. Also needed
are ways to measure parts of
trees that have not usually been
sold in the past. When old growth
was harvested, a great deal of
residue— branches, needles,
broken boles— was left on the log¬
ging site after the boles were re¬
moved. When second growth is
harvested, the wood that used to
be called residue will increasingly
be used for products, including
energy, and forest managers will
need ways of calculating its vol¬
ume or weight. Forest managers
have also known for some time
that crowns and logs left behind
provide wildlife habitat and aug¬
ment soil nutrient reserves as they
decay. With intensive utilization,
including whole-tree harvesting,
better information and methods
are needed for evaluating which
material should be left behind and
which should be removed from
a site.

To help deal with the emerging
issues of harvesting second-
growth timber, scientists in the
Biomass and Energy Unit are
taking advantage of research op¬
portunities provided by current
management situations. When
they design research to provide
critical information that local forest
managers need to solve current
problems concerning smaller
trees, they plan it with the goal of

Many tree measurements are needed to
produce accurate weight and volume
estimators.

also adding to the store of tools
and information that have broader
application to the management
and utilization of second-growth
timber throughout the region.

One such study has been com¬
pleted on the Olympic National
Forest. Another in south-central
Oregon is in the final stages. The
studies were done with the coop¬
eration of land managers, timber
operators, and public agency
staffs. This cooperation has made
possible work that otherwise
would not have been done, or at
least would have been much more
difficult and costly. Although they
help answer the questions of local
land managers, these studies are
also part of a larger plan to pro¬
vide this type of information
throughout the West.

“Doghair” stands
in Washington

On the Olympic National Forest,
forest managers needed help in
their attempts to harvest dense
stands of overstocked, small
timber— the kind known as
“doghair”— so the area could be
planted with more productive
stands. The stands to be replaced
consisted of stagnated, 50- to
60-year-old western hemlock,
Douglas-fir, and western redcedar,
with density ranging from 2,000 to
more than 25,000 stems per acre.
Most trees were 70 to 80 feet tall;
average stand diameters were less
than 8 inches. Some of the stands
were growing on very steep
slopes. Through repeated at¬
tempts to harvest these stands,
the management staff of the Quil-
cene Ranger District found that
existing harvest methods and
equipment were not adequate for
the job. They also found they
needed to know how to estimate
the amount of woody biomass that
could be marketed and how its
removal would affect future tree
growth.

A new harvesting system, using
inwoods processing, was devel¬
oped by an innovative local timber
operator. This system, involving
new technology and total-tree
marketing, provided the oppor¬
tunity to harvest the doghair
stands where conventional
approaches had failed. It was
decided that even greater gains in
efficiency could be obtained by
developing processing equipment

7

specially designed to handle the
small trees being cut. The commit¬
ment of the land manager and the
timber operator resulted in a con¬
tract in which the Ranger District
provided timber for testing newly
developed equipment provided by
the logging operator. The contract
also incorporated research
planned and conducted by
Howard's unit, both to answer
questions facing the District, and
to expand knowledge about small-
tree harvesting. The research was
made possible with financial
assistance from the Department
of Energy.

Equipment purchased or devel¬
oped for the harvesting and proc-

Because new equipment makes possible
the harvesting of second-growth ponderosa
pine, forest managers need better informa¬
tion to meet the challenging decisions
about utilizing and marketing it.

essmg system included: a feller/
buncher, capable of working on
slopes as steep as 80 percent,
that was used to cut the trees; a
clam bunk forwarder, or skidder,
that transported the prebunched
trees to the processing site; a
mobile loader for sorting and posi
tioning trees for processing; a
prototype chain-flail machine for
cleaning bark and limbs from
trees destined for chipping; a
chipper that processed debarked
trees into clean chips; and a
shredder that produced hog fuel
from all tree parts not converted
into logs or chips. Costs and pro¬
ductivity of each piece of equip¬
ment and the entire processing
system were determined.

The findings were specific to the
particular site, but the methods
developed can be adapted to
similar situations. The study
accomplished the following:

• determined the costs and pro¬
ductivity of new equipment;

• described the wood density of
small-diameter trees;

• developed biomass estimators
for trees and tree parts;

• described the distribution of
nutrients in trees, forest floor,
and soil;

• determined the energy value of
chips made from entire trees
and from various tree parts;

• found that the nutrient capital in
living crown material constituted
a small portion of the total for
the site;

• found quite a bit of dead
material on the forest floor;

• found stem densities not appre¬
ciably different from those
found in old-growth trees of the
same species.

Lodgepole pine in
southwest Oregon

The management problem on the
Winema and Deschutes National
Forests in south central Oregon
was what to do about 300,000
acres of lodgepole pine vulnerable
to infestation by the mountain pine
beetle. The possibility of slowing
down the infestation by harvesting
trees larger than 7 inches in diam¬
eter— the preferred habitat of the
insect— improved considerably
after powerplants in northern
California began to show interest
in using the lodgepole for fuel.

8

One of the questions that needed
study was how to estimate the
biomass of standing trees so that
both buyer and seller could have
a basis for talking about amounts
and value. Perhaps more impor¬
tant was the need to find out what
nutrients were located in various
tree components, ground cover,
and soil, and what would be the
effect on the nutrient capital of the
pumice soils if whole-tree harvest¬
ing removed them.

Research designed and con¬
ducted in three Ranger Districts
by scientists in Howard’s unit is
expected to produce information
that will be applicable to the entire
area of south-central Oregon
where lodgepole pine grows on
pumice soils. The information will
not only assist local forest man¬
agers but will also add to the
store of knowledge about harvest¬
ing second-growth trees.

The expected results will include:

• new equations for predicting the
amount and distribution of
woody biomass in trees and
stands;

• equations developed from many
measurements of sample trees
to provide information buyers
and sellers can use in talking
about biomass products by
volume or weight;

• estimates of the amount of
carbon, nitrogen, sulfur, and
phosphorus in all ecosystem
components: boles, crowns,
and roots of trees; shrubs,
dead trees, and soils;

• equations that allow calculation
of the loss of nutrients that will
result from any level of harvest,
including whole-tree harvesting;

• an index of competition based
on crown width, crown length,
and tree height and basal area;

• an evaluation of the effects of
competition on the distribution
of biomass and nutrients in
trees.

Conclusion

The information from completed
and future studies will be organ¬
ized into computer models that
display relations that have been
established by research. One such
model, already developed, can
allocate the entire tree or stand to
potential products, based on utili¬
zation standards specified by the
user. For example, the product
allocation model can be used to
evaluate the products that result
from different utilization standards
for a particular stand, or to see
how the same standards will pro¬
duce a different mix of products
when applied to different stands.
Use of the model will be ex¬
panded as data for other species
and geographic areas become
available.

The unit is now planning a similar
study of ponderosa pine on the
Deschutes National Forest in
central Oregon. This is another
instance where research was
spurred by land managers’ in¬
terest in finding out the amount of
biomass that might be harvested
and the relation between harvest
and future productivity. The ap¬
proach will be similar to that used
with the lodgepole pine study now
nearing completion. Similar results
are expected. The results will be
available to support harvest deci¬
sions and will also be used in a
long-term study of the effects of
intensive harvesting on the pro¬
ductivity of second-growth
ponderosa stands.

Howard says, "The goal of our
research is to provide forest man¬
agers and timber operators with
information that will allow them to
describe and evaluate economical¬
ly acceptable strategies for har¬
vesting second-growth stands and
to better understand the effect of
a planned level of utilization on
other resource values.”

People who would like more infor¬
mation about the work on harvest¬
ing second-growth trees can write
to the Biomas and Energy Re¬
search Unit at the Pacific North¬
west Station or call (503)231-2030,
(FTS 429-2030) and talk to Jim
Howard, Mike Lambert, Susan
Little, or Dale Waddell.

9

Where deer
and cattle
roam

by Richard Pearce, for
Pacific Southwest Station

What do today's wildlife managers
have in common with the game
keepers of Elizabethan England?
“A concern that cattle might
adversely affect native deer popu¬
lations,” says John Kie of the
Pacific Southwest Station.

"The controversy about livestock
and deer goes back literally hun¬
dreds of years,” Kie, a research
wildlife biologist, said during a re¬
cent interview. “More recently,
there has been specific concern
by the California Department of
Fish and Game and biologists
studying the Western Sierra
Nevada ranges, that cattle and
deer may compete for various
resources.”

But not until Kie and his co¬
workers from the University of
California at Davis, and the Califor¬
nia Department of Fish and Game,
launched their series of coopera¬
tive studies, was there any hope
that the debate could be settled
scientifically. Now, their ongoing
investigations are giving land and
wildlife managers the data they
need to make rational decisions
about how to maintain Sierra
Nevada rangelands to the benefit
of both deer and cattle.

“In the past, there simply were no
guidelines for incorporating deer
management objectives into the
establishment of stocking rates,”
said Kie. “Decisions about what
stocking level to use on the deers’
summer range have been based
solely on how cattle might reduce
forage in a single area like a
meadow.”

Kie further noted that the few
studies conducted previously
failed to relate the observed ef¬
fects to different levels of cattle
stocking.

“The studies were not of the best
design because they did not man¬
ipulate the main factor— the live¬
stock,” said Kie.

In order to provide a benchmark
against which the basin-wide im¬
pact of various levels of grazing
could be gauged, Kie and his col¬
leagues have been evaluating the
effects of no, moderate, and
heavy cattle grazing on deer habi¬
tat and behavior over entire home
ranges. There are several ways
livestock could adversely affect
deer. By trampling low-lying
foliage, cattle could reduce or
eliminate the cover fawns use for
protection against predators. Ex¬
cessive grazing could alter the
quality or amount of food available

in a particular area, forcing adult
deer to expend precious energy
seeking food or shelter elsewhere.
The PSW cooperative studies
measured these effects separately
in a series of investigations over
three years. Still to be determined
is whether deer survival is actually
threatened by such pressures, but
the findings thus far have pro¬
vided several clues about which of
grazing’s many effects are likely to
have an impact on deer stamina.

Working with Kie are Eric R. Loft,
John W. Menke, Montague Dem-
ment, Joy Winckel, and Emilio A.
Laka of the Department of Agron¬
omy and Range Science at UC
Davis, and Ron C. Bertram of the
California Department of Fish and
Game.

The Forest Service provided much
of the funding for both projects,
with the California Department of
Fish and Game supplying field
workers and material.

10

Research on interaction between mule deer
and cattle was conducted in the McCor¬
mick Creek Basin on the Stanislaus
National Forest in California.

The researchers chose two study
areas, both in the Stanislaus
National Forest: McCormick Creek
Basin, a mountain basin at about
2,500 meters, and Bell Meadow at
a slightly lower elevation. The
McCormick Creek Basin was
divided into three pastures; one
stocked at a normal rate (moder¬
ate grazing), another at a high
rate (heavy grazing), and a third
with no. cattle. In the Bell Meadow
study, a single riparian-meadow
habitat was partitioned into small
pastures and stocked with tame
deer and cattle at four different
stocking rates. In both series, the
treatments were rotated yearly
through the pastures.

Kie characterized the McCormick
Creek studies as “broad scale,”
designed to study the effects of
cattle on several aspects of deer
behavior over a variety of habitat
types. The Bell Meadow study, in
contrast, was an “intensive” inves¬
tigation of cattles’ effects within a
single habitat.

Hiding cover

Deer are most susceptible to
predators during their first two
months of life, and biologists have
long suspected that a reduction of
suitable cover caused by exces¬
sive cattle grazing may appreci¬
ably lower fawn survival. Flowever,
changes in hiding cover over an
entire season at different levels of
grazing has never before been
measured.

In the McCormick Creek study,
the researchers quantified hiding
cover for fawns by recording the
percent of a square grid, one
meter on a side, and divided into
0.01 -m2 squares, that was ob¬
scured by vegetation or debris
when observed at several points
from the center of 0.01 hectare
plot. Complete results were pub¬
lished in the Journal of Wildlife
Management (vol. 51(3):655-664).
The principal findings of the
study? Even when no cattle were
present, hiding cover declined
over the course of the summer
due to the maturing and weather¬
ing of vegetation. But with cattle
present, the decline was
accelerated.

“The natural loss of hiding cover
during the course of the summer
really doesn’t matter,” said Kie,
explaining that “by the end of the
summer, fawns have matured and
their defense strategies have
shifted more to outrunning pred¬
ators.” The most important time
for cover, Kie said, is early in the
summer “when the fawns are
young they depend on hiding to
escape predators.”

But when cattle are present the
loss of cover occurs sooner, caus¬
ing a large proportion to be lost
early in the season when fawns
need it the most. “What's more,”
said Kie, “the more cattle you put
in there the quicker that decline
occurs.”

The researchers presented their
data in a graphic form with per¬
cent change of hiding cover for
three different vegetation types
plotted against zero, medium, and
high stocking rates (Figure 1). To
reduce the natural effects of
weathering, only the change in
cover from the beginning of the
summer to mid-August was in¬
cluded. The resulting negative cur¬
vilinear relationship turned out to
be a fairly good descriptor of what
cattle can do to hiding cover in
the three major deer habitats.

11

“A resource manager who is con¬
cerned about hiding cover for
fawns can go to the chart and see
that it would be unwise to stock
heavier than 0.5 animal units per
hectare,” Kie said, commenting
on the utility of the graph. "On the
other hand, if there’s a situation
where there aren’t a lot of pred¬
ators around and fawn survival is
good, a manager might want to
stock at some other level based
on some other goal.”

Kie is careful to point out that his
production curve is not necessarily
applicable to areas outside the
McCormick Creek Basin.

Habitat choices

Also under study at McCormick
Creek Basin is the way deer select
and use their habitats under the
three different cattle stocking
rates. If cattle are altering normal
patterns, then the scientists might
gain insight into the ways deer are
affected by grazing and to what
degree.

To get a handle on behavior,
three types of selection were con¬
sidered: first-order selection, which
is the deer's choice of a physical
or geographical range; second-
order selection, which compares
the percentage of habitat types in
the home range, i.e. , aspen,
meadow-riparian, montane shrub,
conifer, dry meadow, and sage¬
brush, to that of the basin as a
whole; and third-order selection,
which relates to how deer go
about using the different habitats
within the home range.

Abundant hiding cover in aspen habitat
can last through September in the absence
of cattle grazing

L JH * 1 f

Excessive grazing by cattle can eliminate
cover for mule deer in aspen habitat by
September .

In order to study habitat choices,
the researchers had to be able to
look at second- and third-order
selection by following the move¬
ments of single deer. To do this,
they outfitted each animal with a
radiotransmitting collar. Its location
at any given moment could then
be determined by triangulation.
After several days of record¬
taking, a map of a deer’s home
range (representing second-order
selection) could be drawn.

Comparing the composition of the
home range to that of the basin
as a whole, the scientists dis¬
covered that, when no cattle were
present, deer tended to select
more meadow-riparian habitat
than is typical for the basin. In
contrast, when cattle were pres¬
ent, the deer selected home
ranges with less meadow-riparian
habitat.

Just the opposite was seen for the
montane shrub habitat, located
mainly on slopes surrounding the
basin. With no grazing, deer
showed no preferential selection of
this habitat. But with moderate,
and even more with heavy stock¬
ing levels, deer increased the pro¬
portion of montane shrub habitat
in their home ranges.

12

Thus it was discovered that cattle
were, for whatever reasons, alter¬
ing the deer’s second-order
selection choices.

It was also observed that deer
increased the size of their home
ranges in the presence of cattle.
The studies showed, too, that the
cattle affected third-order selec¬
tion, that is, the time deer spent in
a particular habitat within the
home range.

"When cattle were around, deer
take in more area than they would
normally,” said Kie. “They spend
more time in a bigger home range
and use habitats differently.”

With no grazing, deer favored
aspen groves. With cattle present,
however, the time a deer spent in
the aspen habitat fell significantly.

At all stocking rates, mule deer
also spent a good deal of time in
the preferred meadow-riparian
habitat, while avoiding sagebrush.
Montane habitats were occupied
with equal frequency whether
cattle were present or not.

Interpreting the results, Kie said
that “sagebrush is not a very
useful habitat for deer in McCor¬
mick Creek Basin; it’s dry, there's
not a lot of grasses or forbs out
there for forage, and the cover is
very low.” In contrast, he said that
“aspen overstory provides both
thermal cover, screening the sun
in the daytime and holding in
warmth at night, and some inter¬
ception of rainfall and hail. Most
importantly, it provides a good
source of high quality forage.”

Although no significant difference
was noted in a deer’s occupation
of sagebrush between the heavily
grazed, moderately grazed, and
ungrazed lands, Kie said the trend
was towards less avoidance of the
sparse habitat with heavy grazing.

“All this suggests to me that as
deer are being displaced from the
preferred habitats they are going
to the less preferred ones,” Kie
said. “Under conditions of no
grazing in the pastures, they don’t
spend any time at all in the sage¬
brush. But they’ll spend a little bit
more time with moderate grazing
and more time still with high graz¬
ing. It’s as if they were being
forced into those habitats.”

The most dramatic shift in third-
order selection occurred in the
aspen habitat where deer spent
significantly less time with moder¬
ate and heavy grazing levels.

Kie believes that cattle grazing
does not appreciably affect aspen
overstory but that it does take out
a lot of the low-strata cover.

“Once this resource is gone,” he
says, “the deer spend less time in
the aspen habitat.”

Kie does not endorse the fre¬
quently made argument that deer
shun a habitat simply because
cattle are present. “There are
plenty of examples both today
and dating back to the 1600's
where people report seeing deer
and cattle feeding side by side.

My feeling is that the social intoler¬
ance is a lot less important than
what the cattle are doing to the
forage and hiding cover
resources,” Kie said.

Also under investigation was how
cattle might affect deer activity
within their home ranges. Kie sus¬
pects that an increase in energy
expenditure might be one of the
prices a deer must pay when cat¬
tle force it to move from preferred
habitats, or to increase the size of
its home range.

Cattle tend to prefer some of the
same habitats deer do. They con¬
centrate in creek bottoms and in
aspen patches. But as the deer
expand their home ranges, they
tend to use more of the steeper
slopes.” Kie muses that if he were
a deer, he would want a home
range “that is small and one
where I wouldn’t have to climb up
and down a hill everyday to get
water, forage, and cover.”

Feeding, traveling,
or resting?

Additional clues about how cattle
might be affecting a deer's energy
expenditure can be obtained by
monitoring its activity on a 24-hour
basis.

Radiotransmitting collars were
equipped with tip switches that
changed the frequency of the
emitted pulse depending on
whether the deer’s head was up
or down. When the deer was
feeding and its head was down,
the collar gave off a slow pulse.

13

When the deer was not eating
and had its head up, the pulse
rate was high. To find out if a
deer was moving, the researchers
simply exploited the fact that the
strength of a radio signal abruptly
changes whenever an animal
shifts its location.

Findings for 1984 and 1985
revealed that with higher stocking
rates, the deer spent more time
feeding and less time resting than
they did when no cattle were
present.

“Although the relationship was not
a very tight one, we saw a distinct
pattern that, as the cattle ate more
and more of the forage that was
available in the meadow-riparian
habitat, the deer were spending
more time feeding and traveling,”
Kie said.

The researchers also examined
whether there was any difference
in the way deer broke-up their ac¬
tivities over a 24-hour period. The
biggest response they saw was in
the length of the resting bouts.

“In 1984 with no grazing the aver¬
age resting bout was 112 min¬
utes," Kie said. “With moderate
grazing it was 56 minutes while
under heavy grazing it was 32
minutes."

A similar though less dramatic
pattern was seen in 1985. That
was a drought year in the Western
Sierra, and forage conditions were
poor. Accordingly, resting periods
were much shorter. Still, there was
a decline in the length of the aver¬
age resting bout as a function of
cattle grazing. Kie said that with
no grazing in 1985, they meas¬
ured an average resting bout of
36 minutes. That dropped to 33
minutes with moderate grazing
and 25 minutes under heavy
grazing.

“The overall trend was for deer to
rest for shorter periods of time
when there were a lot of cattle
around,” Kie said summing up
both years’ data.

But is a decline in resting time at
the expense of increased foraging
necessarily a problem for deer?

To find a suitable answer to this
all-important question, Kie turned
to recently amended ideas about
what costs an animal must pay in
order to survive.

Optimal foraging theory

In the past, biologists have looked
at animal survival largely from the
standpoint of forage energetics,
that is, how much energy does an
animal have to expend to obtain
life-sustaining nutrients? Recent
work, however, has broadened
this “optimal forage theory" to
include, in addition to the energy
costs of finding food, the costs of
reproducing and avoiding pred¬
ators as well.

“It doesn’t do an animal any
good to use a minimum amount of
energy to get all of its nutrients if
it's doing it in an area where there
are alot of predators around,”
insists Kie. “In some cases the
animal would be better off to
spend a little more energy getting
food in a different area it it’s much
safer from predation.”

In the case of the mule deer, Kie
believes it is in the animal’s best
interest to obtain food quickly.
“Every minute a deer takes look¬
ing for food means that it is less
wary of predators.” Kie says he
can’t prove that those deer that
spend more time foraging are any
less likely to survive a summer
than deer that spend less time
foraging, but he calls it a “reason¬
able assumption that fits with the
new developments in optimal
foraging theory.”

Practical implications

To help managers with their deci¬
sions about how best to stock a
deer’s home range with cattle, Kie
hopes to derive production curves
similar to the one for hiding cover
to express the various response
variables such as habitat selection,
home range size, and resting
bouts as a function of different
cattle stocking rates.

14

"We want to have a whole family
of curves so that we can make
some recommendations about
what cattle stocking rates ought to
be to achieve a particular man¬
agement goal,” said Kie. "One
manager might be more con¬
cerned about predation on adults
than fawns, in which case it would
be more appropriate to consult an
activity graph to see how percent
of time feeding varies with stock¬
ing rate. A different manager
might be concerned that the
deer’s fat reserves at the end of
the summer aren’t high enough to
sustain them through the winter. In
that case, he might want to re¬
duce the cattle stocking rate to
the point that the deer have small

home ranges at the bottom of the
basin where forage is abundant,
so that the deer don’t have to
spend all day going up and down
hills or running around large home
ranges to get their forage.”

How a particular manager uses
the production curves, Kie says,
“will depend on what the situation
is with each deer herd, and what
the herd management goals are.”

Bell Meadow:
a study in detail

Early on in the McCormick Creek
Basin study, it became apparent
to the researchers that the mea¬
dow habitat was a significant one
for mule deer. Accordingly, it was
decided to put a single montane
meadow habitat "under the micro¬
scope” to evaluate more closely
how cattle affect deer behavior.

For starters, they looked at feed¬
ing and rumination habits.

They divided Bell Meadow into
four small pastures and stocked
them at the four rates: not grazed,
lightly grazed, medium grazed
and heavily grazed. "There's a
tremendous amount of information
that’s just now being analyzed,”
said Kie. Nevertheless, he said
that the UC Davis researchers
were able to conclude in a prelim¬
inary report that deer probably
suffer a decline in nutrient intake
with heavy cattle grazing. The
investigators observed that with
increased stocking rates and the
associated decline in meadow
biomass, there were increases
both in number of bites per
minute and steps per minute
taken by deer.

"Instead of being able to stand
in one place for a long time and
taking several bites, deer were
having to take just a few bites and
then move on," said Kie. The find¬
ings suggest to Kie that a greater
searching effort was required by
deer to find the preferred plant
species.

15

Curiously, at the highest stocking
rate, total time spent feeding de¬
creased. “That may seem contra¬
dictory to the McCormick Creek
results,” Kie admitted, “but Bell
Meadow was a confined habitat —
the deer couldn’t go to other habi¬
tats like they could in McCormick
Creek Basin.”

Other preliminary observations
with high stocking rates were that
the number of boli the deer rum¬
inated per minute decreased and
the chews per bolus increased.

“To me that suggests that with
heavy stocking rates the deer are
taking in such poor quality forage
that they have to bring up a bolus
and chew it longer to break down
the tough cell walls,” Kie said. In
McCormick Creek Basin when
things got bad in the meadows,
the deer could go to other habi¬
tats. They went up into the mon¬
tane shrub habitats and they went
to conifer habitats. There they in¬
creased their time grazing. They
couldn't do that in Bell Meadow,
so their only strategy was to take
in lower quality forage and spend
more time ruminating.

Effects not always
negative

The authors of the Bell Meadow
report concluded that heavy stock¬
ing rates should be avoided so
that deer are not deprived of
much-cherished, high quality
forage. But Kie emphasizes that
the consequences of cattle graz¬
ing are not always negative.

Tame deer were used to study foraging
behavior in detail at Bell Meadow on the
Stanislaus National Forest.

“There are some things coming
out of the Bell Meadow study that
suggest, at least in the short run,
that some level of stock grazing
may actually be beneficial to
deer,” Kie said. “There’s a good
argument, advanced by others,
and which we discovered, too,
that with very light stocking rates,
cattle remove some of the coarser
vegetation— the grasses and the
sedges— and that tends to en¬
courage the growth of forbs
(broadleaf plants) that are higher
in nutritional quality and preferred
by deer.”

Kie added, however, that it has
yet to be determined precisely
what level of cattle stocking im¬
proves forage conditions for deer.
But as the data are analyzed fur¬
ther and more studies conducted,
he is hopeful that this and other
relationships between cattle and
deer will become clearer. As a
range animal that has co-existed
with cattle for thousands of years,
deer have proven that they have
what it takes to survive. But, only
with further scientific study into
how deer may be ill-affected— or
benefitted— by cattle, will wildlife
managers be able to ensure their
continued existence well into the
future.

For additional information, contact
John G. Kie, Forestry Sciences
Laboratory, 2081 E. Sierra Ave¬
nue, Fresno, California 93710,
(209) 487-5589.

16

Help for
determining
carrying
capacity

by Rick Fletcher
Rocky Mountain Station

The most extensive area of grass¬
land west of the Rocky Mountains
is the semi-deserts of New Mex¬
ico, Arizona, and northern Mexico.
Here, wide horizons of grasses
such as blue grama, alkali saca-
ton, and Indian ricegrass unite
with mesquite, acacia, and a
variety of cacti and other arid land
plants for as far as the eye can
see.

Rangeland in this region is an im¬
portant resource. Not only does it
provide forage for domestic live¬
stock, its primary economic value,
it also offers wildlife habitat, water,
and recreation resources. And, as
open space, it provides a much-
needed esthetic buffer against
spreading urban pressures. But
much of the land being used for
grazing is in poor condition be¬
cause of overuse. In fact, some
areas have been continuously
grazed year-round for decades.

One people that rely heavily on
grazing is the Southwest Indian
tribes. Realizing that many of their
ranges were in less than optimal
condition, and wanting to make
improvements, in 1986 the Albu¬
querque (New Mexico) Office of
the Pueblo Council, Bureau of In¬
dian Affairs approached the Rocky
Mountain Station with a request—
develop a guidebook for estimat¬
ing livestock carrying capacity on
semi-desert Indian reservation
rangelands in the Southwest.

So, working closely with the
Bureau of Land Management and
the Soil Conservation Service,
scientists at the Station’s Forestry
Sciences Lab in Albuquerque set
out to do just that. Today, that
handbook is completed, and ap¬
plies not only to Indian reservation
ranges, but ranges throughout
most of the Southwest.

Southwest rangelands are most valuable
for livestock grazing.

The objectives of the handbook,
based on operating procedures
currently used by the U.S. Forest
Service, Bureau of Land Manage¬
ment, and the Soil Conservation
Service, are to:

1) outline range inventory pro¬
cedures that provide data with
which to plan range management
activities;

2) provide a rational basis for
making an initial estimate of live¬
stock carrying capacity; and

3) outline a step-by-step method
for evaluating range response to
management procedures currently
being used. This includes guide¬
lines for adjusting livestock num¬
bers as the trend of a specific
range condition becomes ap¬
parent over time.

17

Mapping

Good range management is great¬
ly dependent upon accurate, up-
to-date range maps. The booklet
explains that "depending on the
size and complexity of a range
unit, maps may be drawn directly
on USGS and topographic sheets,
orthophoto quads, or stereoptically
on the most recent aerial photos".
The goal is to map vegetation to
an intensity of 40 acres, or smaller
if an area is especially productive,
or if it represents some particular
problem (e.g. an area of poison¬
ous plants).

This overgrazed range is typical of many
areas in the Southwest

An accurate vegetation map, in
combination with a soils map, is a
basic management tool for plan¬
ning and management of a range.
Other range and vegetation map¬
ping strategies are detailed, such
as capability classification— which
rangelands should or should not
be grazed (i.e. no capacity, poten¬
tial capacity, full capacity for graz¬
ing); seasonal and topographical
considerations; and soil
compaction.

Sampling and analysis

Because a thorough understand¬
ing and objective evaluation of
range vegetation is essential to
preparing a realistic estimate of
livestock carrying capacity on a
range unit, much of the guide is
devoted to vegetation sampling
and analysis.

Stratification, plant community
structure analysis, forage produc¬
tion estimates, utilization estimates,
and production utilization surveys
are all discussed.

The health or vigor of range
plants, their composition and
density, age or size class, and
production are important in com¬
puting carrying capacities. These
factors may vary substantially with¬
in short distances. Techniques to
use range transects are described
in the book, and will help land
managers and users arrive at
meaningful production and utiliza¬
tion averages.

Carrying capacity

Finally, and the bottom line,
techniques for determining actual
carrying capacity are detailed.

Carrying capacity is the long-term
ability of a range unit to support
grazing without materially increas¬
ing soil erosion or otherwise harm¬
ing the natural plant cover. Espe¬
cially on the semi-arid ranges of
the Southwest, it can vary widely
from year to year, depending on
rainfall amount, distribution, and
intensity.

Most key forage plants in the
Southwest tolerate light to moder¬
ate grazing without serious long¬
term effects. In fact, the growth of
some species appears to be
stimuated by grazing. However,
beyond a certain level of use, any
species can be adversely affected
by grazing.

18

A carrying capacity figure for
long-term use, if based on a
single year’s forage production or
range performance, can be quite
misleading, unless the growing
season in question happens to be
near average in rainfall. Thus the
initial carrying capacity estimate
must be adjusted up or down in
successive years as range per¬
formance data accumulate. The
longer the recording period, the
nearer the “true” level of stocking
can be approximated.

Though there are several methods
for establishing carrying capacity,
“historical basis” and “allowable
use” are considered two of the
most reliable, and are outlined in
the guidebook.

Historical basis

Most southwestern ranges have
been grazed by domestic livestock
for a long time, some for two cen¬
turies. One method of obtaining
the best records possible of the
prior grazing loads on a range
unit is by consulting ranchers, old-
timers, and others who may have
specific knowledge of the area.
Related data sources are past
brand inspection and shipping
records.

Allowable use

Allowable use is the level of graz¬
ing utilization that can be per¬
mitted on an area when all influ¬
encing factors are considered.

This method determines carrying
capacity by adjusting stock num¬
bers up or down to attain an
"allowable use” for the range unit
as a whole. The book discusses
all related factors such as key
forage plants, soil stability and
range condition trends, topog¬
raphy, water, class of livestock,
season of use, etc.

The guidebook contains a number
of forms and tables, along with
detailed instructions, to assist
users in arriving at an accurate
carrying capacity estimate. Two
computer diskettes are also in¬
cluded containing 1) COSAM— a
program that computes vegetation
parameters that are being ad¬
dressed, and 2) GUOSAM— which
computes forage production for a
given area. Both programs use
raw field data to produce final
calculations for estimating carrying
capacity.

Measuring forage production.

Techniques described in this
guidebook are supplemented by
technical literature particularly ap¬
propriate to southwestern range
problems. While providing step-by-
step instructions for particular
analysis procedures, it should be
used as a supplement to the
rancher’s and resource profes¬
sional’s own field experiences, not
as a substitute for them.

If you would like more information
about this guidebook, or the re¬
search described in it, contact
Project Leader Earl Aldon, For¬
estry Sciences Laboratory, 2205
Columbia, S.E., Albuquerque,

New Mexico 87106, (505)
766-2384, FTS 474-2384.

19

New from
research

Classification
of serai plant
communities

Habitat type classifications focus
on the environmental (site) differ¬
ences affecting vegetation. While
providing a logical framework for
studying succession, they typically
offer no classification of serai com¬
munities. But a new Intermountain
Research Station General Techni¬
cal Report explores the changes
in vegetation and related resource
values occurring over time in one
forest environment. The Grand Fir/
blue Huckleberry Habitat Type in
Central Idaho: Succession and
Management , General Technical
Report INT-228, presents a
classification of serai vegetation
designed for general field use.

The successional classification
system is based on 92 sampled
stands, and includes 21 potential
tree layer types, 28 shrub layer
types, and 36 herbaceous layer
types categorized by a taxonomic
classification.

The Grand Fir/Blue
Huckleberry Habitat
Type in Central
Idaho: Succession
© and Management

Robert Steele
Kathleen Geier-Hayes

Within the system, the relative
position of a classified stand can
help predict its successional path¬
way. Resource managers will find
it useful that some types of serai
vegetation are strongly related to
a specific disturbance, while other
types develop mainly through
uninterrupted succession. These
cause-and-effect relationships are
presented in various ways in sec¬
tions dealing with classification
as well as with management
implications.

The classification approach devel¬
oped in the report recognizes the
individual nature of specific sites
in terms of existing and potential
plant species composition. It also
recognizes that land managers
need site-specific guidelines for in¬
tensive management purposes.

The somewhat independent nature
of succession between the tree,
shrub, and herbaceous layers is
treated separately. The report in¬
dicates some interrelationships of
site treatment, planted tree sur¬
vival, competing vegetation, and
pocket gopher populations. And
most important, it provides a com¬
mon framework for communication
among various disciplines involved
in site management.

20

Timber harvest
has little effect
on nutrient output

The chemical output from high-
elevation, snow-zone watersheds
on the eastern slope of the Cas¬
cade Range in Washington is not
particularly sensitive to timber har¬
vest. This was the conclusion of
scientists who examined chemical
output, climatic change, and tur¬
bidity and sediment production in
a main watershed, four subwater¬
sheds, and a control watershed
near Wenatchee, Washington.
Stream measurements were made
from April to October for 3 years
before and 3 years after logging
by skyline and helicopter systems.

Air and water temperatures gener¬
ally increased as more of the site
was exposed. Stream turbidity and
sediment production increased
during road construction but
declined to background levels
within 2 years.

The mechanisms of nutrient losses
are complicated and influenced by
depressed or excessive precipita¬
tion. The authors state that clear-
cutting only portions of watersheds
apparently reduced the harvest
impact on all nutrient output. They
believe that logging methods and
cutting percentages were ade¬
quate to protect the water
resource.

Copies of Changes in Water Qual¬
ity and Climate After Forest Har¬
vest in Central Washington State,
Research Paper PNW -388, are
available from the Pacific North¬
west Station.

Results of spacing
after 25 years

A new report from the Pacific
Northwest Station provides a syn¬
thesis and an evaluation of earlier
progress reports of spacing trials
in Douglas-fir, western hemlock,
and western redcedar at the
University of Columbia Research
Forest in the Fraser River Valley of
British Columbia. It should help
managers choose optimum
spacings.

Five spacing trials, covering a
range of plantation spacings from
0.9 to 4.6 m, were established
from 1957 to 1967 on a very pro¬
ductive site to assess the effects
of spacing on tree and stand
development. The report also in¬
cludes a summary of the designs
and the periods of evaluation.

Results suggest that choice of
initial spacing is one of the most
important decisions made by man¬
agers. In economic and biological
terms, the 3.7- and 4.6-m spac¬
ings appear to be near optimum
for most regimes for producing
lumber. Combined with pruning,
the same spacings should be op¬
timum for producing clear lumber
and veneer. The 0.9- and 1.8-m
spacings produce maximum
biomass.

Spacing trees more widely be¬
tween rows than within rows
(rectangular spacing) can reduce
planting and tending costs and
facilitate uniform spacing within
the first thinning. Pruning of widely
spaced trees to enhance the qual¬
ity of the lower bole is strongly
recommended.

Write the Pacific Northwest Station
for copies of Development Over
25 Years of Douglas-flr, Western
Hemlock, and Western Redcedar
Planted at Various Spacings on a
Very Good Site in British Colum¬
bia, Research Paper PNW-381.

21

Aspen damage
from clearcutting

Substantial acreages of aspen in
the Rocky Mountains are being
regenerated by clearcutting.
Resulting suckers will develop
under different circumstances and
ecological conditions than did their
parent stands. Young stands of
suckers are easily damaged by
hail, snow, frost, insects, diseases,
browsing, and branch breakage-
all of which help contribute to
decreased growth, internal defect,
and mortality.

Recent studies by scientists at the
Rocky Mountain Station suggest
that suckers produced following
clearcutting may be similar in
quality to natural stands at com¬
parable ages. Aspen suckers from
1 to 19 years old were studied in
32 clones in Colorado. The high¬
est frequency of damage was
caused by disease, followed by
dead terminal leaders, insects,
broken branches, wetwood, trunk
wounds, frost, basal wounds,
browsing, hail, snowbreak, poor
form, and root wounds. Re¬
searchers are quick to point out
that the quality of suckers can be
more fully assessed closer to
maturity.

Additional details on this research
are available in Aspen Sucker
Damage and Defect in Colorado
Clearcut Areas, Research Paper
RM-278. The Rocky Mountain
Station has copies.

Computer program
analyzes channel
cross sections

Research Note PSW-396 de¬
scribes DEBRIS, a new computer
program for analyzing channel
cross sections. Written in
FORTRAN 77, DEBRIS is a menu-
driven, interactive program for
recording and plotting survey data
and for computing hydraulic vari¬
ables and depths of scour and fill.
By using menus, operators do not
need to know any programming
language. The five routines are:
entering data, plotting, scour and
fill, hydraulic variables, and com¬
puting x-y coordinates.

DEBRIS can be used on any Data
General MV series computer using
the AOS/VS operating system. For
more information, request the
above Research Note, DEBRIS: A
Computer Program for Analyzing
Channel Cross Sections, from the
Pacific Southwest Experiment
Station.

22

Improving
reforestation
on harsh sites

Container-grown Ponder osa Pine
Seedlings Outperform Bareroot
Seedlings on Harsh Sites in South¬
ern Utah presents the results of a
field comparison of ponderosa
pine plantings on the Dixie
National Forest after five growing
seasons. Results on five sites vary
from little difference in perform¬
ance on the best sites, to signifi¬
cant differences on the harshest
sites, providing resources man¬
agers with suggestions for better
success in reforestation.

The low levels of available soil
moisture during the spring plant¬
ing season make reforestation a
challenging job. Replanting has
often been necessary, costly, and
not always successful. But until
this study was initiated, only bare¬
root seedlings had been planted.
The trial of container-grown stock
was based on prior North Ameri¬
can studies to improve survival
and tree growth. After five grow¬
ing seasons, survival averaged 90
percent for all containerized grown
seedlings and 79 percent for
bareroot stock.

Container-Grown
■SL Ponderosa Pine

Seedlings Outperform
i§ Bareroot Seedlings
on Harsh Sites in
Southern Utah

John P. Sloan
Lewis H. Jump
Russell A. Ryker

The report includes a summary of
other field tests comparing bare¬
root and container-grown seed¬
lings of North American conifers.
For a copy, request Intermountain
Research Station Research Paper
INT-384.

Use of home range
by mountain lions

A Research Note recently issued
by the Pacific Southwest Experi¬
ment Station carries the prelim¬
inary results of studies by Dr.
Donald Neal and George Steger,
both of the Station’s Forestry
Sciences Laboratory in Fresno,
and Ronald Bertram of the Califor¬
nia Dept, of Fish and Game. Their
study seeks to evaluate the rela¬
tionship between mountain lions
and the much-depleted North
Kings deer herd in the Sierra.

In an area on the west slope of
the central Sierra Nevada in
California, scientists attached radio
collars to 19 mountain lions and
monitored them daily. Results in¬
dicate a density of adult mountain
lions of one per 33.3 km2, and of
adults and kittens of one per 20.9
km2. Their preliminary results, in¬
dicating a high mountain lion:deer
ratio, suggest that mountain lions
could be preventing the deer herd
from recovering.

To learn more, contact PSW
Station and request Research
Note PSW-392, Mountain Lions:
Preliminary Findings on Home-
Range Use and Density in the
Central Sierra Nevada.

23

Is pruning
financially
feasible?

Will the increase in value of
products justify the investment in
pruning the lower limbs from coast
Douglas-fir? It all depends on the
costs of pruning, interest rates,
and the price premium for
clear wood.

Researchers at the Pacific North¬
west Station provide explanations
and a computer program to help
managers calculate the possible
advantages from pruning. A
spreadsheet program, based on
data from an actual mill study that
compared the lumber recovery
from unpruned Douglas-fir logs
and logs from trees pruned 34
years earlier, was developed to
simulate the increase in grade
recovery and financial return
after pruning.

(The product recovery study was
the subject of a feature story in
Forestry Research West, March
1986, “How About Pruning
Douglas-Fir?” The pruned logs
produced more clear products of
higher value than did unpruned
logs. But whether the increase in
value was enough to offset the
cost of pruning and still return a
profit has to be calculated on the
basis of costs and expected
returns.)

Results of the analysis show that a
5-year difference in the time of
pruning can make a substantial
difference in financial return. The
earlier pruning is done, the better.
The number of years between
pruning and harvest that will give
the best return depends on the
site, interest rate, and whether
trees were fertilized.

For help in drawing some conclu¬
sions about the financial feasibility
of pruning coast Douglas-fir, ask
for two publications from the
Pacific Northwest Station: Financial
Analysis of Pruning Coast
Douglas-fir, Research Paper
PNW-390, and PRUNE-SIM Users
Guide, General Technical Report
PNW-209.

Silviculture
practices for
Black Hills
ponderosa pine

A new report from the Rocky
Mountain Station offers guidelines
that will help forest managers and
silviculturists develop even- and
uneven-aged cutting methods for
ponderosa pine in the Black Hills
of South Dakota and Wyoming.

Guidelines cover damaging
agents, cutting history, even- and
uneven-aged cutting methods,
managed stands, costs of sale ad
ministration and logging, multiple
use silviculture, and comparisons
of cutting methods.

Described cutting methods are
designed to maintain water qual¬
ity, improve wildlife habitat, en¬
hance recreation opportunities,
and provide wood products.

For your copy of Silvicultural
Systems, Cutting Methods, and
Cultural Practices for Black Hills
Ponderosa Pine, General Tech¬
nical Report RM-139, write the
Rocky Mountain Station.

24

United States
Department of
Agriculture

Forest Service

Intermountain
Research Station

Research Note
INT-376

Forest Succession in
Western Montana —
a Computer Model
Designed for
Resource Managers

Robert E. Keane II'

ABSTRACT

/I quantitative computer model of succession (FORSUM)
has been developed for use hi/ land managers in predicting
response afforest vegetal ion to silvicultural (reutments mid
wildfire. FOIiSUM allows evaluation of the effects of alter¬
native treatments. The nuxlcl predicts temporal changes in
canopy cover for major species in four habitat types com¬
mon to western Montana Species establishment is based on
regenerative strategies; then subsequent changes in cover
for each species are modeled using regression equations.
FOIiSUM also contains an easy-to-use. interact ire data
input routine with error cheeking ea liability and two skill
levels. Output is offered in both tabular and graphic
format. In a validation of FORSUM, species cover was
predicted accurately 7 4 percent of the time. Accuracy
ranged from Hit percent to 78 percent. The computer code
consists of 21 subroutines and was written in FORTRAN
77. It can be modified to incorporate additional habitat
ith minimal effort.

Ill)

KEYWORDS: pathway model, regression, interactive pro¬
gram, vegetal response, succession

Predicting the composition of plant communities that
arise after different silvicultural treatments or wildfire
plays an important role in forest management. Because
successional community composition is strongly influenced
by the composition of the predisturbance vegetation and
by type and intensity of disturbance, managers can man¬
ipulate successional trends to meet management objectives
by selecting different silvicultural treatments (Arno and
others 1985). But choosing the best treatment to meet
management objectives can sometimes be difficult because

there are few quantitative methods available to predict
postdisturbance plant coverages. Successional classification
systems such as Arno and others (1985) and Steele (1984)
relate successional trends to wildfire and site treatment
but yield only qualitative predictions. To overcome this
problem, a study was conducted to quantify coverage
response to various disturbances and then develop a com¬
puter model for predicting succession in four habitat types
commonly found in west-central Montana. This model,
called FORSUM (a FORest Succession Model), is current¬
ly available for use by land managers. The purpose of this
paper is to describe the assumptions and operations of
FORSUM as well as present an evaluation of the accuracy
of the model.

FORSUM is based on the classification system of Arno
and others (1985). In this classification system, site char¬
acteristics, predisturbance plant composition, and type and
severity of treatment define major successional pathways
within a habitat type phase. Plant species establishment
after a disturbance is based on regenerative strategies.
Subsequent growth in cover is projected using regression
equations. FORSUM predicts plant coverage for 74 species
of trees, shrubs, and herbs. The model is based on an anal¬
ysis of 774 actual stands, including some paired treated
and untreated stands. Because all data were collected
within the study area defined in figure 1, it is strongly
recommended that use of FORSUM not be extrapolated to
areas outside these boundaries.

The model predicts succession for seven phases in the
following Montana habitat types (Pfister and others 1977):

1. Pseudotsuga menziesiil

Physocarpus malvaceus (PSME/PHMA)

2. Pseudotsuga menziesiil

Vaccinium globulare (PSME/VAGL)

3. Abies lasiocarpalXerophyllum tenax (ABLA/XETE)

4. Abies lasiocarpalMcnziesia ferruginea (ABLA/MEFE)

These habitat types comprise more than half the forested
landscape in west-central Montana. There are four treat¬
ment types represented in the model: (1) stand-replacing

Predicting species
coverage in western
Montana — FORSU M
to the rescue

A new computer model will help
forest managers predict response
of forest vegetation to silvicultural
treatments and wildfire. FORSUM
(a FORest SUccessional Model)
allows evaluation of the effects of
alternative treatments, so that
treatments yielding plant commu¬
nities that best meet management
objectives can be used. FORSUM
predicts changes over time in
canopy cover for 74 major
species of trees, shrubs, and
herbs in four habitat types com¬
mon to western Montana. The
model is based on an analysis of
774 stands, .including some pared
treated and untreated stands.

Plant species establishment after a
disturbance is based on regenera¬
tive strategies; then subsequent
changes in cover for each species
are modeled using regression
equations. In a validation of
FORSUM, species cover was
predicted accurately 74 percent
of the time.

FORSUM is currently available for
use in Perkin-Elmer and Data
General minicomputer systems
and UNIVAC mainframe com¬
puters. It is designed so additional
habitat types can be added later.

An Intermountain Research Station
publication describes the assump¬
tions and operations of FORSUM
as well as presenting an evalua¬
tion of the accuracy of the model.

Request Forest Succession in
Western Montana— a Computer
Model Designed for Resource
Managers, Research Note
INT-376.

25

Shrub

information for
fire management

The shrub component of a stand
can be enhanced or depleted by
prescribed fire if managers under¬
stand the biology of the shrub
species. Prescription goals might
be to increase shrub availability
for wildlife browse or to reduce
shrub abundance to favor trees.

Fire Response of
Shrubs of Dry Forest
Habitat Types in
g§ Montana and Idaho

Nonan V Noste
Charles L Bushey

But foresters responsible for plan¬
ning fire management and specify¬
ing burn objectives are often more
familiar with the effect of fire on
trees than on shrubs. A recent
Intermountain Research Station
General Technical Report supplies
information that will help in design¬
ing effective prescribed fire treat¬
ments for shrub manipulation.

Fire Response of Shrubs of Dry
Forest Habitat Types in Montana
and Idaho , General Technical
Report INT-239, contains summary
information on the biological attrib¬
utes and response to fire for 20
shrub species. It includes informa¬
tion on the regeneration capabil¬
ities, response to fire, and utiliza¬
tion of shrub species important or
common to the dry forest sites.
Response to fire is classified by
reproductive strategies and how
the species persists in the stand.
Utility of the species for browsing
by livestock and wildlife is
included.

Census time
for western trout

There are significant interregional
differences between the density
and biomass of trout in the west¬
ern United States, according to
the results of a study recently
published by the Intermountain
Research Station. Generally, trout
density was highest in the Rocky
Mountains, while trout biomass
was greatest in the Sierra Nevada
and Upper Gila Mountain eco-
regions. Density and biomass of
brown trout were significantly
greater than those of brook, bull,
cutthroat, and rainbow trout. And,
streams occupied by multiple
species of trout had densities and
biomasses that were not signifi¬
cantly different from those streams
occupied by single species.

Density and Biomass of Trout and
Char in Western Streams, General
Technical Report INT-241, reports
the first compilation of trout popu¬
lation characteristics in the western
United States. It present informa¬
tion from a variety of stream habi¬
tats representative of western eco¬
systems, for use by biologists and
aquatic resource managers evalu¬
ating their particular aquatic habi¬
tats. The data will assist land-use
planning and management re¬
quirements concerning fish popu¬
lations as outlined under Federal
law, and will serve as an aid for
considering fish population needs.

U S GOVERNMENT PRINTING OFFICE: 1988— 576-028 85,182 REGION NO 8

26

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STAMP _ STAMP

Round two for
northern Idaho
habitat types

The widespread use of habitat
type approaches to forest site
classification has emphasized the
need for management of eco¬
systems rather than individual re¬
sources. Today’s foresters want
site classifications that provide
greater detail than earlier versions
in terms of management utility and
multiresource application. While
early habitat type classifications
serve as models, they can be
refined to better reflect the full
range and diversity of forest
environments.

Forest Habitat Types
, of Northern Idaho:

A Second
Approximation

Stephen V. Cooper
Kenneth E. Neiman
Robert Steele

Forest Habitat Types of Northern
Idaho: a Second Approximation
presents a land classification sys¬
tem for that part of Idaho from the
Salmon River north to the United
States-Canada border. It refines
the Daubenmires’ widely used
1968 classification by developing
a system based on reconnais¬
sance and detailed sampling of
approximately 1,100 stands. The
Daubenmire habitat type concept
is used to construct a hierarchial
taxonomic classification of forest
sites. Eight climax series, 49
habitat types, and 60 additional
phases of habitat types are de¬
fined. A dichotomous key, based
on indicator species used in
development of the classification,
is provided for field identification
of the syntaxonomic units.

Request Intermountain Research

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