Biodiversity and Poverty Reduction;

The importance of biodiversity for ecosystem services.

31 May 2007

UNEP-WCMC, 219c Huntingdon Rd, Cambridge, CB3 ODL
01223 277314, www.unep-wcmc.org

UNEP-WCMC - Biodiversity and Poverty Reduction

Report prepared by:

United Nations Environment Programme World Conservation Monitoring Centre (UNEP-WCMC)
219c Huntingdon Road

Cambridge

CB3 ODL

www.unep-wcmc. org

Authors:
Neville Ash and Martin Jenkins

Acknowledgements

The authors would like to thank Harold Mooney and Walter Reid of Stanford University, Jo Elliott,
Izabella Koziell, Anna Balance, Daniel Bradley, Simon Anderson of DFID, Steve Bass of IIED, and
Elaine Marshall, Philip Bubb and Valerie Kapos of UNEP-WCMC, for reviewing the draft report.
Contributions to the report were also received from Nigel Varty, Michelle Taylor, Edmund McManus,
Claire Brown, Zoe Cokeliss, and the many authors of the Millennium Ecosystem Assessment Current
Statues and Trends Report, Biodiversity and General Synthesis volumes.

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Contents
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2 Biodiversity and ecosystem services: Concepts and approaches .............:csssessesesssseees 6
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UNEP-WCMC - Biodiversity and Poverty Reduction

Executive Summary

Purpose of this Report

This report reviews existing scientific knowledge regarding the links between biodiversity and the
sustainable provision of ecosystem services, and considers the implications of these links for
development policy. It does not set out to assess the value of ecosystem services to the poor, on which
there is a growing understanding presented in other reports and publications, and so does not present
the economic valuation of biodiversity or ecosystem services. The report considers biodiversity in the
broadest sense, to include variety at the genetic, species and ecosystem levels, and interactions between
components of biodiversity, and is therefore not restricted to a consideration of species diversity alone.
The links between biodiversity and ecosystem services presented in this report underpin the
relationship between the environment and development, and as such contribute towards an
understanding of the most effective national, bilateral, and international efforts to achieve the
Millennium Development Goals, and towards an improved understanding of the true values of
biodiversity.

Importance of Biodiversity for the supply of Ecosystem Services

Biodiversity underpins the ecosystem services that all people ultimately depend on at all scales, from

the individual to the global, rich and poor alike. Important ecosystem services on which poor people

are particularly dependent, include:

e varied diet (including flavourings and micronutrients), famine foods and food security - provided
directly by components of biodiversity that are consumed, and through a wide range of biodiversity
that is crucial for food production, including that involved in the services of pollination, pest and
disease control, and soil fertility.

e water quality and availability (including regulation of flooding events), and erosion control -
affected variously by vegetative cover at local and landscape scales

e medicines and health, both through the supply of natural medicines, and through the regulation of
infections and emerging diseases.

e cultural values, closely tied in many societies to components of biodiversity, typically at the
species or landscape level.

Current levels of scientific understanding of the links between biodiversity and ecosystem services

have established that:

e Interactions between components of biodiversity (such as pollination, decomposition, and
interactions between plants and soil organisms) are fundamental to the functioning of ecosystems,
and to supporting the continued supply of ecosystem services.

e Diversity at genetic and species levels is important for maintaining the adaptability of ecosystems
to changing environmental conditions, for example increasing climate variability and predicted
changes in global and regional climate, and for maintaining the capacity of ecosystems to supply
the combinations of a variety of services.

e Many of the substitutes for ecosystem goods and services, where available, have significant
collateral costs — for example, use of pesticides has important human health implications; use of
fossil fuels has climate change and often aerosol pollution implications; use of fertilisers has water
quality implications. Sometimes these costs may be born by the users of the substitutes (eg.
implications for farmer health of on-farm use of pesticides), but they are often externalised (eg.
downstream problems of water quality caused by runoff from farms with high fertiliser input).

e Threshold effects in declining biodiversity are important in many instances. These are manifested
when reduction in biodiversity to a certain level causes a sudden collapse in a system’s ability to
deliver particular services. These have most clearly been demonstrated in aquatic ecosystems, for
example where increasing nutrient loading has led to dramatic reduction in oxygen levels and the
emergence of so-called “dead zones” in lake and coastal waters, and where the persistent

UNEP-WCMC - Biodiversity and Poverty Reduction

overharvesting of fish stocks has caused sudden, apparently irreversible collapse in those stocks.
Threshold effects caused by reductions in biodiversity on land are less well documented, but have
been demonstrated in a range of habitat types.

And so it is clear that some level of biodiversity is absolutely necessary for human existence, rich and
poor people alike. However, there is no simpie answer to the questions “how much biodiversity do we
need?” or “how much biodiversity can we afford to loose?” This is for a number of reasons:

e Biodiversity is a complicated concept with many dimensions. There is no single measure or metric
that can adequately describe it. Similarly, ecosystem services are themselves multidimensional.
These questions will therefore have a different answer in different contexts and at different scales.

e There is considerable scientific uncertainty, and vigorous debate, about the exact role of diversity
in ecosystems and the relationship between the amount of any particular component of biodiversity
in an ecosystem and the way that ecosystem functions. Three main approaches have been used to
examine such relationships: theoretical, experimental and observational. Each can provide valuable
insights, although each is also heavily compromised.

e Although capabilities for predicting some thresholds are improving, and increased risks of change
can be determined, for most thresholds in most ecosystems, current understanding is unable to
predict the thresholds where change will be encountered.

e Many ecosystem services may at some scales be substituted for by non-biodiversity alternatives,
derived from technology, inorganic materials (of which petrochemicals are a special case) and
human labour. In some instances, and at local scales, ecosystem services may be brought in from
outside

Implications for the World’s Poor

The limited purchasing power of poor people leaves them less capable of buying-in substitutes for local
ecosystem services from outside. They are therefore highly dependent on the integrity of their local
environment, for example for the supply of wild foods during times of famine, insecurity or conflict.
Maintenance of a heterogeneous local environment provides the widest possible range of ecosystem
services, reduces the exposure of local people to risk and lessens their dependence on the vagaries of
global markets or on development assistance. When considered from the perspective of poor people it
is this /ocal level of biodiversity that is important: the distribution and abundance of wild species, the
range of crop plants and livestock and the diversity of ecosystem types directly available to them. Not
only are poor people generally not in a position to buy in substitutes for ecosystem goods and services,
they are often forced to bear the externalised costs of other people’s use of substitutes for ecosystem
goods and services — for example, they may live in places that suffer the effects of pollution and
eutrophication, or are displaced by hydroelectric projects, or conversion of natural or semi-natural
forests to high intensity agriculture.

Implications for Development Policy
Recognition of the role that biodiversity plays in underpinning the ecosystem services has development
policy implications at all levels from the international to the local or community.

International policy implications

Partnerships between development agencies and other government departments are essential to ensure
coherent and consistent policies regarding biodiversity and poverty in all policy arenas. This includes
including those concerned primarily with trade and finance, as well as those with a focus on
environment and development.

Development agencies are well-placed to encourage appropriate strategies to meet development and
environmental targets and indicators at national and international level, for example under in the
Millennium Development Goals. MDG 7 ‘ensuring environmental sustainability’ underpins all the
other goals, as without it elimination of poverty will only be at best temporary and at worst illusory.

UNEP-WCMC - Biodiversity and Poverty Reduction

The incorporation of the CBD’s 2010 biodiversity target into MDG7 has already contributed to this
objective, and to ensuring policy coherence between biodiversity and poverty sectors, although in
many instances, MDG7 is not considered or addressed by development agencies to the extent of other
goals.

Influencing policies and institutions at the national level
Development agencies could further encourage governments to harmonise their various strategies and
action plans, including sectoral plans, poverty reduction strategies, national strategies for sustainable
development and national environmental and biodiversity strategies and action plans. Of particular
importance in this regard are:
e adoption of participatory bottom-up planning approaches
e adoption of a people-centred ecosystem approach as agreed under the CBD
e promotion of systems of tenure and access to resources that are equitable and that promote
sustainable use of natural resources through long-term management
e adoption of legal frameworks that allow for the integrated planning and management of
resources at the landscape level
e information sharing within and between governments, including that arising from
environmental assessment processes, and government-funded science.

Influencing policies and planning at the regional level

Development agencies could encourage management and planning practices that maintain or restore
environmental heterogeneity at the landscape level. This is the simplest way to ensure that poor people
have access to the range of ecosystem services that they need while at the same time allowing
individuals or families to manage their own resources in ways that most suit them. Experience to date
has shown that it is possible to develop multi-stakeholder plans and information sharing mechanisms
successfully at the landscape level (particularly in coastal zones through integrated coastal zone
management approaches), but that it is often then difficult to establish legal frameworks for the
implementation of these plans. Hence the importance of encouraging national-level legal reform, as
indicated above.

Influencing activities at the community, farm or individual level

The adoption of low-impact management practices should be encouraged in production systems where
these can be shown to deliver significant on-site benefits. Two important examples are the use of
integrated pest management techniques and commercial production of environmentally-friendly goods.
In both cases barriers to adoption by poorer people can be relatively easily overcome with external
assistance.

Where the livelihoods of poor people depend on or involve harvest of wild resources, at minimum
efforts should be made to ensure that the harvest of these specific resources is sustainable. Although it
is in principle not difficult to design sustainable harvest regimes, it has proven difficult to find
successful mechanisms for their implementation. Development agencies could play a useful role here
in widely disseminating best practice in natural resources management.

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1 Introduction to study

fil Purpose and focus of report

This document provides an overview of the state of science relating to the role of biodiversity in the
supply of “ecosystem services” (the benefits that people derive from ecosystems), highlighting what is
known about how changes in biodiversity affect ecosystem services. It then presents the implications of
these connections for development policy. It does not set out to assess the value of ecosystem services
to the poor — it is assumed that the reader already has an understanding of the importance of
agricultural production, waste processing, natural medicines, regulation of water quality and quantity,
and other ecosystem services, information on which is widely available in a range of other reports,

such as the range of Millennium Ecosystem Assessment technical and synthesis reports (available from
www.MAweb.org). Where information is available, an emphasis is placed on demonstrating thresholds
and the consequences of abrupt or non-linear changes to biodiversity.

Biodiversity is considered here in a broad sense, including variety at the genetic, species and ecosystem
levels, and is therefore not restricted to a consideration of species diversity alone. This report presents
the state of knowledge regarding how much biodiversity is needed for the sustainable supply of
ecosystem services in the present, and into the future (see Figure 1). The report also reviews the level
of understanding of the reliance of ecosystem services on various aspects of biodiversity, such as
variety (e.g. number of species (species richness), genetic variability), abundance (e.g. number of
individuals or populations in a given location), /evel of organisation (e.g. genetic, population, species,
or ecosystem diversity or abundance), and biological interactions (e.g. between pollinator species and
plants, and between predators and prey).

With consideration of non-utilitarian values:
Additional amount of biodiversity that should be conserved for
non-utilitanan values such as intninsic values and the equitable
distribution of biodiversity.
With consideration of resilience, thresholds,
and option values:
Additional amount of biodiversity that should be conserved for
utilitarian reasons because of its role in maintaining capacity to
adapt to change, as precaution against thresnolds, and for option
and existence values.
With consideration of the biodiversity role
in ecosystem services:

Additional amount of biodiversity that should be conserved for
utlitanan reasons because of its role in providing and sustaining
ecosystem services.

Business as usual

Vi What will remain under current trends and policies given trade-offs
_» with economic development, agriculture. etc.

Please note that the circles sizes are

only conceptual and do not correspond
to any calculation or estimate.
Source: Nillennium Ecosystem Assessment

Figure 1. Conservation of biodiversity under different value frameworks — How much biodiversity
might we need in the future? This report assesses the current state of knowledge regarding the sizes of these
various circles, considering the importance of various atiributes of biodiversity for the supply of ecosystem
services, both now and into the future. There is little doubt that there will be less biodiversity in the future than at
present, but note that the sizes of circles in this graphic are conceptual. Source: Millennium Ecosystem
Assessment.

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Biodiversity provides benefits to both the rural and urban poor. Although the majority of the world’s
poor currently live in rural areas, where they are most directly dependent on ecosystem services for
their well-being, the rapidly-growing proportion that live in urban and peri-urban areas are also
ultimately dependent on ecosystem services, both locally and from a distance. Ecosystem services
particularly important to the growing number of urban poor include waste processing and
detoxification, regulation of water and air quality, and services supporting small-scale agricultural
production.

The issues considered in this report underpin the relationship between the environment and
development at all scales, and as such relevant information is contributed here for national, bilateral,
and international efforts to sustainably achieve the United Nations Millennium Development Goals and
other poverty reduction strategies. The report lends support to, and builds on, previous publications and
strategies on biodiversity and development.

LE? Biodiversity and Ecosystem Services in the International Context

This report comes at a time of rapidly increasing awareness of the importance of biodiversity and
ecosystem services. The Millennium Ecosystem Assessment (MA)' provided a baseline assessment of
the condition of the world’s ecosystems in providing benefits to people. It concluded that many of the
benefits that people derive from ecosystems are being degraded, largely because their values are not
captured in current economic systems. This finding is supported by other recent studies, such as that
commissioned by UK Defra, and produced by EFTEC in 2005 on the Economic, Social and Ecological
Value of Ecosystem Services, and reports of UNDP, the World Bank and others, such as World
Resources 2005; The Wealth of the Poor.

The role and value of biodiversity and ecosystem services has been recognised at the centre of
international efforts to reduce poverty and promote sustainable development, through the framework of
the Millennium Development Goals. MDG 7, on environmental sustainability, calls for governments to
reverse the loss of environmental resources, and although the indicators for monitoring progress
towards this goal are not well developed, or comprehensive, the recent incorporation of the “2010
biodiversity target” (see below) into MDG7 has made the connection between biodiversity and the
MDGs explicit. The Convention on Biological Diversity (CBD), signed by over 180 governments,
manifestly recognises the important role of biodiversity in development, through its overarching
objectives of conservation and sustainable use of biodiversity, and the equitable sharing of benefits
arising from its use. Government Parties to the CBD, including the UK, have adopted a target,
endorsed by the World Summit on Sustainable Development, to achieve, by 2010, a significant
reduction of the current rate of biodiversity loss at global, regional, and national levels as a
contribution to poverty alleviation and to the benefit of all life on Earth. Despite this, there has been a
tendency at the national level, and at the international level with development donor agencies, to move
away from an explicit focus on biodiversity and ecosystem services in recent years. This may in part be
due to a focus on short-term gains for some development targets, many of which come at the expense
of environmental considerations, and longer-term sustainable development strategies. It may also be
partly a result of the incorporation of environmental issues into national programmes of work without
providing appropriate support for their effective implementation. The move by bilateral and
international donors towards direct budgetary support of governments without the appropriate
environmental considerations in place is likely to further exacerbate the situation.

Additionally, at the national level within governments, and internationally through the various
institutions and agreements, biodiversity-related policies are most frequently developed in isolation

' The Millennium Ecosystem Assessment (MA) was the largest ever assessment of the condition of the world’s
ecosystems to provide benefits to people, and of associated environment and development policy responses. Over
1600 scientists contributed to its findings. The MA was endorsed by the Convention on Biological Diversity, the
Convention to Combat Desertification and the Ramsar Convention on Wetlands. Further information. The
findings of the MA were launched in March 2005, and are available at: www.MAweb.org

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between development, forestry, agriculture, fisheries, water, trade, and biodiversity sectors, resulting in
unintended consequences for other sectors or for ecosystem services. Although not explicitly
recognised, it is clear that many national and international processes, treaties, policies and negotiations
in non-environmental or development sectors relate directly to ecosystem services and biodiversity.
Typically, for example, natural resource commodities such as timber and genetic resources, and trade
in agricultural products, are considered in isolation from their roots as the services of ecosystems. As a
result, the value of the ecosystem in their supply is seldom recognised. In particular, the global trade
agenda, and ongoing discussions under bodies such as the World Trade Organisation are in practice
affected greatly by the changing capacity of biodiversity and ecosystems to provide services, and
decisions taken from the international level through to the individual in all areas of society have the
potential to impact on biodiversity and ecosystems, and thereby on the services from which people
benefit.

2 Biodiversity and ecosystem services: Concepts and approaches

21 Definitions and patterns of biodiversity

Biodiversity is the variability of life, and encompasses diversity at all scales and levels of organisation
from the genetic through populations, species, ecosystems and landscapes. However, it is most clearly
manifested in the variety of different kinds of organisms and habitats in the world. It is the variety of
organisms, interacting with the physical landscape, that creates the range and diversity of ecosystems.
At global level, biodiversity is very unevenly distributed: that is, some parts of the world are far more
biologically diverse than others. The pattern is complex but by no means random. The most important
overall trend, manifest in terrestrial, freshwater and shallow water marine systems, is for species
diversity to increase from the polar regions to the equator. This is because in general, warmer areas are
more diverse than colder areas. On land there is also a general trend for areas with more rainfall to be
more diverse than drier ones. Geographical variations in diversity are very marked — there are, for
example, differences of two or three orders of magnitude in the diversity of, for example, tree species
in forests between arctic latitudes and equatorial ones.

People have, of course, radically altered biodiversity at a global scale. Most dramatically, on land large
areas of natural habitat have been replaced with agricultural systems. In the great majority of cases
(though not all), agricultural systems are lower in diversity than the habitats that they replaced. They
are also generally dominated by exotic, or non-native, species. In many areas the diversity of natural or
semi-natural systems has been reduced through local and global extinction of species. Through
accidentally or deliberately transporting large numbers of species across the world patterns of diversity
have been further altered: in many cases (for example on some islands such as the Galapagos, and at
the continental scale on most continents) we have actually increased species diversity by introducing
new species, but in many others, and particularly at smaller scales, we have reduced diversity as
introduced species have led to the local extinction of native ones.

2.2 Ecosystem processes and services

Ecosystem processes — those that define living systems — can be seen as flows of matter and energy.
Fundamental to these is photosynthesis, whereby energy from sunlight is used to turn carbon dioxide
and water into oxygen and biomass. Respiration then releases energy, breaking down organic matter
back into, essentially, carbon dioxide and water. Other aspects of ecosystem processes that are also
extremely important include the incorporation of elements from inorganic sources into living systems,
notably including the incorporation of nitrogen from the atmosphere by various kinds of bacteria (also
increasingly carried out through industrial processes) and the decomposition of waste matter so that it
re-enters the various nutrient and mineral cycles. At a planetary level these are the ecosystem services
on which continued human existence is absolutely dependent. More locally, people derive a whole
range of other benefits from ecosystems, such as regulation of water flows and water quality, local
regulation of climate, and stabilisation of land through vegetation reducing soil erosion.

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The range and variety of benefits that people derive from ecosystems have been categorised into:
provisioning services — the products (or goods) obtained from ecosystems; regulating services — the
benefits obtained from the regulation of ecosystem processes; cultural and amenity services — the
nonmaterial benefits obtained from ecosystems; and supporting services — those necessary for the
production of all other ecosystem services. Examples of the various categories of ecosystem services,
and the diverse linkages between ecosystem services and human well-being are illustrated in Figure 2.

CONSTITUENTS OF WELL-BEING

Regulatina

LIFE ON EARTH - BIODIVERSITY
Source: Millennium Ecosystem Assessment

ARROW’S COLOR ARROW’S WIDTH

Potential for mediation by _ Intensity of linkages between ecosystem
socioeconomic factors services and human well-being
(Low —— Weak

Medium — Medium

ME High [-~) Strong

Figure 2. Classification of ecosystem services, and illustration of the linkages between ecosystem
services and human well-being. The strength of the linkages and potential for mediation (for example through
substitution) differ in different ecosystem sand regions. In addition to the influence of ecosystem services on
human well-being, other factors also influence human well-being, such as economic, social, technological and
cultural factors. Source: Millennium Ecosystem Assessment

As} Sources of information — theory and evidence

The great range and diversity of ecosystems found across the planet are a reflection of the range of
different organisms that carry out the functions and processes sketched out above. However, the precise
nature of the relationship between the diversity of organisms and the attributes of ecosystems and
ecosystem processes is only now beginning to be understood, and research into the specific links
between biodiversity and ecosystem services has only really emerged in the last decade (see Figure 3).
Although there is no shortage of hypotheses, there is still not a single convincing explanation for the
patterns of biological diversity that we observe in the world. Without this, any attempts to establish
generally applicable quantitative and causal links between diversity and ecosystem attributes are likely
to be compromised, although again a number of hypothesis are available (see Figure 4).

UNEP-WCMC - Biodiversity and Poverty Reduction

Number of Publications

=
oO
Oo

i

fo.)
oO
— ls

ia tt

30 |

20 4

GEcosystem Services

* soohDll

| @Biodiversity + Ecosystem Services

94 95 96 97 98 99 00 01

02 03 04 05 06 07

Figure 3. Emerging research on biodiversity and ecosystem services. Results represent number of
publications between 1991 and 2007 that included either ‘ecosystem services’, or ‘biodiversity’ and ‘ecosystem
services’ in their titles and abstracts. It’s only for just over a decade that scientific research has focussed explicitly
on the links between biodiversity and ecosystem services. Figure constructed with data from the BIOSIS
literature database.

Ecosystem process

Redundancy

aa

Linear ree

() Becclivemity low Natural
kevsl

Biodiversity

() Rodiverity lam Natural

level

Figure 4. Examples of theoretical hypothesis describing
the relationship between ecosystem processes, and
changes in biodiversity from the natural level. Although
none of these hypotheses are thought to accurately describe
the true relationship between the amount of biodiversity and
the functioning of ecosystems, they nonetheless describe the
general concepts. In cases where there is no biodiversity, there
are no ecosystem processes and functions. At a natural level of
biodiversity, the processes and functions are largely
predictable. However, the consequences of declining (or
increasing) biodiversity from such natural levels is not well
understood for most systems, in large part due to a lack of
empirical and theoretical information, and due to the widely
varying individual properties of ecosystems, and their
components. Source: Loreau M, Naeem §, Inchausti P, 2002.
Biodiversity and Ecosystem Functioning: Synthesis and
Perspectives. Oxford University Press

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This report draws on a variety of synthesized and primary scientific literature. The Millennium
Ecosystem Assessment provides a basis for the conceptual approach to the links between biodiversity
and ecosystem services (see Figure 5). Information from case studies is presented where appropriate, to
highlight key points where larger-scale analysis has not been conducted.

Human Well-being

Freedom of choice and action
based on improved security, health,
good social relations, and basic material for a good life

Fes

Ecosystem Services Drivers

Provisioning Regulating Cultural Demographic
+ Food * Climate regulation + Aesthetic

‘ a Economic
+ Fresh water * Flood regulation * Spiritual

Socio-political

«Timber and fibre | | * Disease regulation + Educational Z
«Fuel * Pollination + Recreational Science and technology
« Medicines « Intrinsic yalues Cultural and religious

Biodiversity Pressures

Habitat changes
Invasive species
Climate change
Pollution
Overexploitation
Natural hazards

Ecosystems, species, populations and genes

Abundance, distribution, composition, diversity and interactions

Figure 5. Conceptual approach to the relationship between biodiversity, ecosystem functioning, and
ecosystem services. The links between biodiversity and ecosystem services form the focus of this report.
Modified from the Millennium Ecosystem Assessment.

Three main approaches have been used to tease out relationships between biodiversity, ecosystem
functions and attributes, and ecosystem services - namely theoretical, experimental and observational.
Each can provide valuable insights, although each is also heavily compromised.” Nevertheless, it is
possible to make some observations about the probable nature of links between diversity and
ecosystem processes and attributes and, more importantly, show that diversity undoubtedly plays a

* Theoretical models and experiments are both compromised by the need for simplifying assumptions, so that it is
unclear to what extent any findings apply in more complex real-life situations. Most experiments either use very
simplified model ecosystems in laboratories, or manipulations of simplified systems, usually temperate, low-
diversity, grasslands in field situations. Even these often present statistical problems in interpretation. Dealing
experimentally with more complex systems presents almost insurmountable problems of statistical analyses.
Moreover, experiments are invariably carried out at very small scale and over timescales that are short in
ecological terms and negligible in evolutionary ones. The use of observations of existing patterns of diversity and
ecosystem processes and attributes is compromised by imperfect data and the fact that demonstrating correlations
between different characteristics does not necessarily say anything about causality (are highly productive, highly
diverse systems diverse because they are productive, or productive because they are diverse?).

UNEP-WCMC - Biodiversity and Poverty Reduction

vital role in the range of important ecosystem services. Examples of recent studies that have
demonstrated links between changing diversity and various ecosystem functions are shown in Table 1.

Table 1. Examples of the demonstrated effects of increasing diversity on ecosystem functions.

Effects of Increasing Diversity Source/Authors

Artificial system of simplified communities of Productivity increased Naeem et al. 1995
terrestrial plants, animals and single-celled
organisms in a controlled chamber (Ecotron study)

Drought resistance enhanced Tilman et al. 1994

Fungi associated with plant roots (mycorrhizae) Plant nutrient capture and productivity van der Heijden et al.
increased 1998

Experimental community of single-celled organisms | Ecosystem reliability (and insurance) Naeem and Li 1997

(microbial mesocosm) enhanced

Aquatic single-celled organisms Less variable community and respiration McGrady-Steed et al.
1997

Aquatic single-celled organisms Increase in productivity and number of Naeem et al. 2000
carbon and algae sources utilised

Microscopic insects and other species in soil Decomposition rate increased Heneghan et al. 1999
Productivity increased Hector et al. 1999

Jonsson and Malmavist
2000; Jonsson et al.
2001

Wetland vegetation Algal and total plant biomass increased. Englehardt and Ritchie
phosphate loss decreased 2001

Increase in non-timber ecosystem services | Pejchar and Press 2006

Mediterranean landscape (pine forests. oak Increased pollination service to wild Potts et al. 2006
woodland, managed olive groves) flowers but also crops

Semi-natural grasslands

Stream-dwelling organisms feeding on dead plant
and animal matter (detritivores)

Increased litter decomposition

Decrease in pollution of aquatic systems Marrs et al. 2007
Semi-arid rangelands Increase in productivity and the diversity O Farrell et al. 2007
of ecosystem services available
Native hardwood forests Increased biomass accumulation and Thomas et al. 2007
carbon sequestration

Updated from: Giller, P., and G. O’Donovan, 2002. Biodiversity and Ecosystem Function: Do Species Matter?
Proceedings of the Royal Irish Academy. 102B 3 129-139.

24 The importance of diversity

Clearly, some level of diversity is required to maintain ecosystem processes at all scales. No single
organism can carry out all ecosystem functions, so even the simplest systems have more than one kind
of organism. At larger scales, no single organism is adapted to the whole range of physical conditions
occurring on the planet, and so the same functions need to be carried out by different organisms in
different places. However, it is not clear that all existing diversity is strictly necessary in the functional
sense. Certainly at global level there is undoubtedly what could be described as redundancy. This is
because very similar physical and climatic conditions can be found in widely separated parts of the
world, in each one of which is found a separate suite of species. There are no good theoretical reasons
why the entire set of living organisms of a particular ecosystem in one part of the world could not
replace the organisms of the same ecosystem type in another part of the world, with little if any change
in observed ecosystem processes and attributes. In practice, of course, this is not a realistic possibility.
Of much greater practical interest is the extent to which altering the diversity in a particular place alters

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ecosystem processes and attributes and thereby affects the ecosystem services provided. This is the
focus of much of the rest of the report.

Des) Thresholds in biodiversity and ecosystem services

Most of the time, changes in ecosystems and their services are gradual and incremental, and most of
these changes are detectable and predictable, at least in principle. However, many examples exist of
nonlinear and sometimes abrupt changes in ecosystems, including disease emergence due to changing
environmental conditions, algal blooms and fish kills due to nutrient loading, fisheries collapses due to
harvesting pressure, and species introductions and extinctions. In these cases, the ecosystem may
change gradually until a particular pressure on it reaches a threshold, at which point changes occur
relatively rapidly as the system shifts to a new condition. Some of these nonlinear changes can be very
large in magnitude and have substantial impacts on the capacity of the ecosystem to provide ecosystem
services, and therefore on human well-being. Capabilities for predicting some nonlinear changes are
improving, but for most ecosystems and for most potential abrupt changes, while increased risks of
change can be calculated, the exact threshold where the change will be encountered cannot easily be
predicted. Where information on thresholds is available, it is included with the discussion of particular
ecosystem services in section 3.

2.6 The dependence of the poor on ecosystem services

Many ecosystem services are partially substitutable. For instance, limited amounts of clean air and
water can be obtained from mechanical filtration, and manufactured materials can be used in place of
timber for housing construction. Declines in the supply of a service from a particular location, such as
fisheries production, can be overcome through transferring demand to other areas where the service is
still provided. However, access to substitutes, and availability of options for the supply of services,
depends critically on socioeconomic status. Poor people, with restricted access to resources, and lower
integration into the cash economy, are less able to substitute human and physical capital, and have less
purchasing power, and are therefore particularly, and most directly, dependent on ecosystem services.
Although poverty rates have been falling in all regions except Sub-Saharan Africa, more than 1.1
billion people remain in extreme poverty, and whilst the well-being of all people is dependent on
ecosystem services, it is the dependence of the poor on ecosystem services that frames the discussion in
this report.

Particularly important services on which poor people are dependent include the provision of food (both
the components of biodiversity that are consumed, and the wide range of biodiversity that is crucial for
food production); medicines and health (through both the supply of natural medicines, and through the
regulation of infectious and emerging diseases); timber, fibres and fuel from forests and other sources;
the regulation of fresh water quality and quantity; protection from (and regulation of) natural hazards;
and cultural benefits of biodiversity. Supporting services on which these various benefits depend are
also crucial, and in particular soil formation, pollination, nutrient cycling, and control of agricultural
pests and diseases. Although the urban poor are buffered against changes in some ecosystem services,
through access to alternatives such as improved water supplies, they are nonetheless also dependent on
the full range of ecosystem services for their well-being. The links between biodiversity and these key
ecosystem services are considered in the following section.

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3 State of knowledge on the links between biodiversity and ecosystem services

This section presents available information on the links between biodiversity and ecosystem services.
Key selected ecosystem services are addressed, in each case presenting the state of knowledge on how
biodiversity contributes to the service, the consequences of changes in biodiversity for the sustainable
supply of the service, and whether thresholds have been identified in the capacity of biodiversity to
supply a particular service. Some sections, such as that on food production, focus largely on species
and genetic level information, whereas others, such as on water quality and natural hazards, focus more
on ecosystem and landscape scale diversity. Such differences reflect both the relative importance of the
various attributes of biodiversity, but also the availability of information relating to the subject area.
Key messages relating to each service are summarised in the opening paragraphs for each section.

3d Food Provision and Food Security

Although a relatively small number of the world’s animal and plant species satisfies the vast
majority of the world’s basic nutritional needs, a much broader spectrum of agricultural and wild
biodiversity remains of fundamental importance in food production systems. For poor people with
limited capacity to buy in foods from outside, access to a diverse range of locally produced foodstuffs
(including those that supply micronutrients and flavourings) is vital for maintaining a balanced and
satisfying diet. Diversity within crops and livestock species (genetic or varietal diversity) is important
in adaptations to particular local conditions, especially in marginal lands, for improving pathogen
resistance and as insurance against future risks in the face of changing environmental conditions.
Diverse farming systems, such as tropical agro-forestry (mixed) systems, maximise use of resources
and are less prone to disease and pest infestations. Wild foods, especially those from inland water
and inshore fisheries, but also a range of terrestrial resources (bushmeat, fungi, wild plants,
invertebrates) are an extremely important resource for many poor people, either as a basic source of
nutrition or as important dietary supplements, or as foods that play a particularly important role
during crop failure and famine. “Wild” biodiversity also underpins many aspects of domestic food
production systems, through maintaining soil structure and fertility, nitrogen fixation, pollination
and natural pest control. Although some or all these functions can in theory be replaced by
artificial, technologically-derived substitutes, these are often expensive and increase the dependency
of poor people on industries and producers beyond their control.

The most direct role of biodiversity in food security is in the use of components of biodiversity as wild
and cultivated foods. In addition, the supply of both cultivated and wild foods is variously dependent
on a range of associated biodiversity, and in particular on the contribution of such biodiversity to the
regulation of pests and diseases, pollination of crops, soil formation and soil fertility. This section
includes an assessment of the state of knowledge of these links, and presents evidence of actual or
predicted thresholds in the provision of food due to changes in biodiversity.

3.1.1 Diversity and availability of food resources

Of the approximately 270,000 known species of higher plants, 10,000-15,000 edible species are
known, of which around 7,000 have been used in agriculture, although only a few hundred are deemed
to be important at a national level. Thirty crop species alone provide an estimated 90% of the world
population’s calorific requirements, with wheat, rice, and maize providing about half the calories
consumed globally. Although several hundred species of animals have been used for human food at
one time or another, 14 species of livestock currently account for 90% of global livestock production.

Despite the relatively low species diversity in most agricultural systems, genetic diversity can be
extremely high. Some crop species include many thousands of distinct varieties, and globally there are
approximately 6,500 breeds of domesticated agricultural animals. However, there is a declining trend
in the diversity of livestock breeds and crop varieties used by farmers, despite the increases in food

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productivity. Approximately 10-20% of current livestock breeds are no longer being used widely, and
it is likely that breed loss will increase with further economic development. For major cereal crops, the
varieties planted by farmers have shifted from locally adapted and developed populations (landraces) to
more widely adapted varieties produced through formal breeding systems (modern varieties). Roughly
80% of the wheat area in the developing world is now sown to modern varieties, and over three
quarters of all rice planted in Asia is planted to improved varieties.

Traditional, landrace-based farming systems tend to contain higher levels of crop genetic diversity than
modernized systems, and although there is little evidence to suggest that the use of traditional landraces
leads to higher yields or to improved overall food security, the adoption of modern varieties among the
three major cereal crops—wheat, rice, and maize—has been less successful in marginal areas, where
landraces are still widely cultivated and are often the main source of crop germplasm. Farmers
continue, for example, to grow landrace varieties of rice in upland rain-fed areas of Southeast Asia, as
well as in deep-water environments, and in parts of West Africa. Relative to wheat and rice, maize has
a much higher proportion of area planted to landraces.

Box 1. The benefits of landraces

Farmers continue to use landraces in some areas rather than modern varieties for a range
of different reasons. First, landraces provide a wider range of end uses and have distinct
culinary purposes, which may also contribute to maintaining a balanced diet. Second,
production factors and risk management provide additional motives for continued use of
landraces. Different landraces are often used to match differences in soil water regimes,
even within the same field, and varieties with different maturities may be used to spread

labour requirements through the season. In addition, where weather patterns are uncertain
or diseases are prevalent, planting several varieties spreads risk. Maintaining a diverse set
of crop varieties to insure against production or market risks may be the most accessible
means of insurance available to low-income households, and finally, in some
unfavourable and heterogeneous environments, appropriate modern varieties have simply
not been developed or are not available, so locally available varieties provide the only
option for food production.

Even low diversity “monoculture” systems in much of the developing world often contain other
dimensions of important agricultural biodiversity: intensive rice monocultures, for example, often
support small areas of vegetable cultivation (on the dikes between paddies) as well as fish cultivation,
and in some rice-growing areas in South and Southeast Asia, fish provide most of the local dietary
protein. The true diversity on which poor farmers and consumers depend is therefore likely to be
considerably higher than many of the global datasets, or available literature, suggest.

Wild foods

Many types of wild food also remain important for the poor and landless, especially during times of
famine and insecurity or conflict, when normal food supply mechanisms are disrupted and local or
displaced populations have limited access to other forms of nutrition. Even in normal times, these wild
land-based foods, from plants, animals and fungi, are often important in complementing staple foods to
provide a balanced diet, and in providing a source of cash income, from trade. Freshwater and marine
fisheries are particularly significant sources of wild food for the poor globally, and it is speculated that
1 billion people rely on fish as their main source of protein, although the per capita consumption of fish
(including crustaceans and molluscs) has declined slightly over the last two decades.

Fish population collapses have been commonly encountered in both freshwater and marine fisheries.
Fish populations are generally able to withstand some level of catch with a relatively small impact on
their overall population size. As the catch increases, however, a threshold is reached after which too
few adults remain to produce enough offspring to support that level of harvest, and the population may
drop abruptly to a much smaller size. The most famous such example is that of the Atlantic cod stocks
of the east coast of Newfoundland, which collapsed in 1992, forcing the closure of the fishery after

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hundreds of years of exploitation. Most importantly, it appears that the collapse of a particular stock
maybe accompanied by significant ecosystem shifts, sufficient that the stock in question may not
recover or may take many years to recover, even if harvesting is reduced or eliminated entirely.

3.1.2 Biodiversity supporting food production

The wider biodiversity of agricultural systems often plays an essential role in supporting crop
production. Soil animals and microbes, together with plant root systems, contribute to maintaining soil
structure, and facilitate nutrient cycling — particularly important in marginal agricultural lands which
are poor in nutrients. Pests and diseases are kept in check by parasites, predators, and disease control
organisms, as well as by genetic resistances in crop plants themselves. Insect pollinators are often
essential for fertilization of crop species. It is not only the organisms that directly provide such services
that are important, but also the associated food webs, such as alternative forage plants for pollinators
(including those in small patches of wild lands within agricultural landscapes) and alternative prey for
natural enemies of agricultural pests. Agricultural ecosystems vary in the extent to which this
biological support to production is replaced by external (human) inputs. In industrial-type agricultural
systems, they have been replaced to quite a significant extent by inorganic fertilizers and chemical
pesticides; but in many areas, particularly in the tropics, agricultural biodiversity provides the primary
forces governing nutrient availability and pest pressure. The following sections provide further
discussion on soil biodiversity, pest control and pollination.

Soil Formation and Plant Productivity

Soil is a complex mixture of inorganic material, dead and decaying organic material, water, and air,
interspersed with living organisms, whose composition varies tremendously with location. Soil is
essential for the growth of virtually all terrestrial vegetation, and agricultural production around the
world. In addition, soil organic matter is the major global storage reservoir for carbon. The most
important soil organisms in terms of numbers and biomass are the microbial organisms - bacteria and
fungi, which in many soils constitute more than 90% of the total biomass. Soil formation is usually a
lengthy process, and climatic conditions are likely to have the most important influences on soil
formation regionally. However, biological populations and processes influence soil composition,
structure and fertility, and are probably a more important determinant of soil formation at a local level,
through the formation and decomposition of soil organic matter (affecting soil fertility and nutrient
uptake by plants, soil acidity and soil water-holding capacity), the regulation of soil structure and soil
water flow (including infiltration and run-off, thereby affecting erosion), and the retention and
availability of soil nutrients, including nitrogen obtained through fixation (affecting soil health and the
efficiency of nutrient cycles).

Of the soil microbes, mycorrhizal fungi play a particularly critical role in enhancing the availability of
soil nutrients and water to plants, and improving plant growth and survival (increased resistance to
disease, drought and extreme temperatures, toxic metals, adverse pH and transplant shock) through a
symbiotic relationship between the fungi and plants. It is estimated that 80% of terrestrial plant species
have a symbiotic relationship with such fungi. Both plant productivity and plant diversity have been
shown to increase with increasing diversity of mycorrhizal fungi and vice versa, particularly in nutrient
poor habitats. Other important groups include the nitrogen-fixing bacteria, such as associated with
legumes, and cyanobacteria that mineralise atmospheric nitrogen, thus replenishing soil nitrogen lost
through leaching and run-off. Interactions between plant root systems and bacteria have a particularly
profound effect on soil quality, and crop health and yield, and this symbiotic relationship is the basis of
intercropping in many semi-natural pasture and agro-forestry ecosystems.

Soil macrofauna such as termites, arthropods and particularly earthworms are important in enhancing
soil structure, chemistry and productivity by mixing the upper soil, which redistributes nutrients,
aerates the soil, increases surface water infiltration, promotes organic matter decomposition and
enhances plant productivity. Above-ground vegetation also has a profound effect on soil formation and
quality, affecting the extent of cover (influencing water runoff and erosion), the type and amount of
organic matter accumulation on the soil (influencing soil pH and nutrient supply). This vegetation also

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provides the food source for most soil microorganisms and hence exerts a strong influence on soil
microbial populations.

Although soil communities are by far the most species-rich components of terrestrial ecosystems, and
species diversity may be several orders of magnitude higher than above ground diversity, soil
communities remain poorly investigated and there has been very little research on thresholds for
ecosystem change in soil systems. Tropical soil biota are particularly poorly documented and
understood. However, field and small-scale experimental evidence suggests that the link between soil
species richness and soil formation or properties is fairly weak, largely due to the high diversity of soil
organisms, and associated high degree of functional redundancy in soils, whereby a broad range of
organisms transfer materials, energy and nutrients through the soil food web. Soil properties are
affected more by the traits of dominant species and by the complexity of biotic interactions that occur
between soil food webs, than by species richness per se. Individual aspects of soil formation and
function can be affected differentially by biodiversity loss, for instance in some cases with reduced
biodiversity resulting in decreased nitrification and increased decomposition. In addition, even if high
species richness does not always play a significant role in maintaining soil ecosystem processes under
normal environmental conditions, it may confer resilience in the face of further environmental stresses.

Box 2. Biodiversity and productivity
The precise relationship between diversity and productivity is not well understood.
Experiments, mostly in temperate grasslands, indicate that reducing diversity within narrow
experimental limits has a negative impact on plant productivity. The two main reasons for this
are likely to be that a range of plants can between them make more efficient use of available
resources (sunlight, carbon dioxide, water, minerals) than one or two plant species, and that
different plants are better adapted to the different micro-habitats that exist in even the most
apparently homogenous expanse of habitat. This might imply that there is a straightforward
connection between diversity and plant productivity, with greater diversity leading to greater
productivity. However, wider observation does not seem to support this. In fact, very high
levels of productivity seem usually to be associated with, relatively speaking, low levels of
diversity. Nutrient enrichment of systems, usually through applications of nitrogen- or
phosphate-containing fertiliser, or both, is usually associated with an at least temporary
increase in productivity and a decrease in diversity. This seems to take place because the
relatively small number of species that are adapted to high-nutrient environments can rapidly
outcompete or displace other species. However maintenance of a high-nutrient, high-
productivity, low-diversity system requires continuous external input — this is the logic that
drives most modern forms of agriculture, where major inputs of nutrients and other factors
(tilling, weeding or, usually, herbicides and insecticides) are needed to keep production at
high levels. It seems likely, although quantitative data are scarce, that increasing diversity
from these very low levels may help to maximise returns over the longer term.

Pest and Disease Control in Agricultural Systems

Natural pest and disease control benefits food security, rural household incomes, and national incomes
of many developing countries, and is strongly dependent on components of biodiversity and their
interactions. The productivity of agricultural systems with high crop genetic diversity or species
richness tends to be more stable over time than that of low-diversity systems, in part due to improved
pest and disease control. In many cases, increased crop genetic diversity and species richness at
different trophic levels leads to more efficient natural control of pests and diseases in agricultural
systems.

Available evidence suggests that conserving the genetic diversity of crops and crop relatives at a global

scale, and deploying that diversity locally, will enhance natural pest control services. Although
empirical evidence is limited, both theory and observation suggest that higher genetic diversity in

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planted crops reduces the chance of crop diseases. Fungal diseases are usually less severe in more
diverse agricultural systems and the use of mixtures of different crop varieties has been shown to
effectively retard the spread or evolution of fungal pathogens of grains. There is some evidence that
these approaches may also be useful for the control of plant viruses.

Both the diversity of natural crop pest predators and the landscape diversity influence pest and disease
control in agricultural systems. Yields of agricultural products may be reduced by attacks of herbivores
above and below ground, fungal and microbial pathogens, and competition with weeds. Many insects,
spiders, and other arthropods are natural predators of crop pests, and provide an especially valuable
service either in the absence of, or as an alternative to, pesticides. In addition to the diversity of
predators themselves, alternative food sources for the predators of crop pests can help stabilise their
populations and therefore provide better pest control. There is some evidence of greater abundance of
natural predators in spatially and temporally diverse landscapes, where asynchronous planting and
patches of uncultivated land provide alternative food supplies for natural pest predators. Crop pest
density in diverse agricultural systems is generally lower than in less diverse systems, and crops have
considerably lower levels of herbivory and increased levels of productivity when planted adjacent to
natural, diverse forests. Sometimes even growing a mixture of two crops is enough for broad pest
control. There is also strong evidence that increasing crop species richness commonly decreases the
severity of weed infestations, leaving fewer resources on which weeds can subsist.

Although natural pest control services are likely to be detrimentally affected by loss of species
richness, in only a few cases has the role of species richness of crop pest predators been tested
explicitly. Perhaps the most comprehensive understanding of the importance of predator species
richness comes from spiders. There are indications of complementarity of function among spider
species—that is, they catch prey using different methods, occupy different microhabitats, or are active
at different times or seasons. Because of this, increasing spider species richness leads to higher and less
variable predation rates and increased food web stability. Crop pest predators may also complement
pesticide use. Because of the high population densities and short life cycles of crop pests, resistance to
synthetic biocides typically evolves rapidly, necessitating continuing investments to develop and
employ new synthetic biocides. The use of natural predators of crop pests can reduce the frequency
with which biocides need to be applied and, hence, the selective pressure and rate at which resistance
evolves.

Pollination

Pollination is the transfer of pollen between flowers, without which flowering plants (which make up
by far the majority of plants, including all major food and medicinal plants, and hardwood timber trees)
cannot reproduce. Although some plants are wind-pollinated (including some staple food crops),
approximately 90% of flowering plants overall, and at least one third of agricultural crops (including
three quarters of the world’s principal crops), and are dependent on insects and other animals for their
pollination.

Worldwide, the number of pollinator species is estimated to be about 300,000, including 25-30,000 bee
species, which together with flies, wasps, beetles, butterflies and moths account for the vast majority of
pollinators, although birds, bats and other mammals also play a role. Although some pollination
systems are highly specialised, such as for Brazil nuts and fig trees, which rely on single pollinators,
most pollination systems tend to be generalized and successful pollination can occur from a variety of
pollinators. In such general systems, plants will rarely completely fail to produce seed or fruit when
their most effective pollinator is removed, but rather the removal of key pollinators results in reduced
quantity or viability of seeds and fruits.

Ata local level there is a strong relationship between effective pollination and pollinator abundance
and diversity. Larger individual fruit of a more uniform shape with better seed viability and production
generally correlate with a greater number of visits from pollinators. Large fluctuations in insect
populations are common, including those of important pollinators. In addition to raised yields, multiple
species of pollinators stabilise pollinator services against variation in population sizes typical of single

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species. However, the relationship between pollinator diversity and successful pollination is likely to
depend more on the identity of the dominant pollinator species than on species richness, and is also
strongly affected by other factors, such as availability and connectedness of suitable pollinator habitat.

Many important wild pollinators are forest species, and several recent studies in Indonesia, Costa Rica
and Brazil have shown that the diversity and abundance of a number of wild pollinators in agricultural
landscapes decline significantly with increasing distance from forest habitats, leading to a decline in
crop yields and fruit quality. This suggests that the most effective pollination services are likely to be
derived from mosaic landscapes, comprised of mixed agricultural and natural vegetation.

3.2 Fresh Water Quality

Fresh water is a resource under increasing pressure with many, often competing uses. Nearly 20%
of the world’s population lack access to clean water supplies, leading to major problems of health
and well-being. A large proportion of available freshwater is derived from land runoff. Often such
water is of low quality owing to high sediment, mineral and nutrient loads as a result of land
degradation and soil erosion within catchments. Catchments with well-managed natural forests
almost always deliver higher quality water, with less sediment and fewer pollutants, than water from
other catchments. Shallow water wetlands with emergent vegetation can improve the quality of water
passing through them by trapping and retaining sediments and removing nitrogen, phosphorus and
other nutrients.

Water quality is strongly affected by ecosystem structure and processes. Ecosystems vary greatly in
their exposure to precipitation and hence as source areas for renewable runoff. Runoff from forest
ecosystems provides some or all of the water for at least 4 billion people, or two thirds of the global
population. Cultivated and urban ecosystems generate much less runoff but, because of their close
proximity to human settlements, contribute to the supplies used by 4—5 billion people. Well-managed
natural forests almost always provide higher quality water, with less sediment and fewer pollutants,
than water from other catchments. Land degradation and soil erosion leads to poor water quality due to
high sediment, mineral and nutrient loads that can impact not only drinking supplies but also the
function of dams. It is widely perceived that forests control erosion and sediment processes and thus
water quality (suspended materials). Riparian forests can form particularly effective barriers that
intercept and absorb sediments, and store and transform excess nutrients and pollutants carried in
runoff from adjacent lands. Undergrowth and forest litter, and at the local level soil depth, structure and
degree of previous saturation are the most important factors influencing this. Forest soils serve in
particular as effective filters that remove organic materials, matter and chemicals from water,
contributing to its purification before it reaches streams and rivers.

Wetlands with emergent vegetation, such as Papyrus swamps, are probably the most efficient habitat
type at trapping and retaining sediment, and can trap up to 80-90% of that from runoff. This function is
particularly important in areas where alternative, artificial water filtering systems are unavailable.
Wetlands can also perform important water purification functions by removing nitrogen and
phosphorous from agricultural runoff. In addition to the removal of excessive nutrients, microbes and
plants in wetlands can also remove or transform water-borne toxins.

3.3 Protection from Natural Hazards

Of the various kinds of natural hazards, floods and fires are the best characterised. Floods have an
impact on more people than all other natural hazards combined. Regulation of water flow is a
product of topography, soil, land-cover and precipitation regimes, all these factors interacting in
complex ways. The capacity of soils to regulate water flow can be reduced by both mechanical
factors (e.g. compaction) and biological ones (e.g. reduction in overall vegetative cover). However,

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there are less clear-cut relationships between flood regimes and the kind of vegetative cover present
in catchments. Cloud-forests are known to exert a strong regulatory influence on water flows.
Elsewhere, forests and forest soil are capable of reducing water flows during small-scale rainwater
events but may have relatively little impact on large-scale ones. Lowland wetlands (e.g. shallow
lakes, swamps and marshes) can play a major role in mitigating impacts of flooding. Fires area
natural phenomenon and in some parts of the world the native biota are well adapted to regular
fires. However the vast majority of fires are now caused by people. Changes in land management,
particularly the replacement of fire-adapted systems with other forms of land-cover, can greatly
increase the intensity and extent of fires when they do occur, increasing the hazard that they pose to
people. Natural ecosystems can also play a role in mitigating other hazards, for example, natural
forests on slopes appear to lessen the frequency of shallow landslides, and mangroves and other
coastal vegetation features can lessen the severity of storm surges.

Of the various natural hazards, the impacts of floods (including coastal flooding) and fires are most
directly influenced by changes in biodiversity, and the role of biodiversity in regulating the impact of
these two hazards is better studied than for other natural hazards.

Floods

The capacity of soils to store water, facilitate its transfer to groundwater, and prevent or reduce
flooding is largely dependent on soil texture, structure and depth. For instance, clay soils have a larger
capacity to hold water than sandy soils, and it is widely recognized that the level of porosity or
degradation of the soils rather than the presence or absence of tree or other vegetation roots is the most
important factor in determining the overall discharge of water from forested areas. The regulation of
water flow by soils is reduced by both mechanical factors, such as exposure of bare soil, soil
compaction by machinery and overgrazing, and biological factors, such as declining activity of soil
fauna, and reduced vegetative cover. However, the relationship between the water retentive capacity of
soils and their species richness or composition is less clear, as is the relationship between the kind of
vegetation cover in a catchment and downstream flood regimes.

The situation is most clear in cloud forest systems, where during prolonged dry periods, streamflow
from forested areas is higher than that from adjacent pasture areas, and after heavy rain streamflow is
lower in cloud forest streams than in streams flowing from pasture areas. The strong streamflow
regulatory functions of cloud forests are also likely to reduce soil erosion and consequently
sedimentation in downstream water resources. In other forested areas, recent studies show that forests
and forests soils are capable of reducing runoff from small-scale rainfall events, but during a major
rainfall event, especially after prolonged periods of preceding rainfall, the threshold of the forest’s
capacity to regulate the flow of water is often exceeded, forest soils become saturated and water runs
off along the soil surface. In such situations, flooding is unlikely to be prevented by forest cover, but
peak streamflow is likely to be less than that which would occur in the absence, or through a reduction,
of forest cover.

It is clear that both soils and forests play a key role in reducing the flow of water to river systems.
However, the varied mechanisms by which trees and other vegetation intercept, use and transpire water
increase the complexity of the relationship between forest cover and streamflow regulation. Evidence
suggests that conversion of natural to managed forest produces a slight decrease in available freshwater
flow and a decrease in temporal reliability (lower long-term groundwater recharge) in most temperate
and warm humid forests, although this is largely dependent on the dominant tree species. Various
studies have shown that water yields from catchments increase following deforestation, but that there is
a fairly rapid return to pre-clearing levels as plant cover regenerates. in tropical woodland, recovery
times of less than five years have been recorded. However, conversion of forest to agricultural land or
pasture can result in permanent increases in stream-flows as short vegetation reduces capacity to
intercept and evaporate rainfall, and to extract water from deeper soil layers during periods of drought.

The role of wetlands in storing water and regulating streamflow is well documented, and is both a
function of their vegetative composition and their characteristically gentle slopes. Lakes and marshes

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attenuate floods by retaining water or storing it in the soil and therefore reducing the need for
engineered flood control infrastructure, and the conversion of wetlands is known to be a major cause
for increased streamflow after heavy rainfall, particularly in the lower reaches of floodplains.

Fires

Fire regimes are determined by a number of different variables, including climate, land cover
(particularly the amount of combustible biomass), and land use. Regions with climates that present
distinct dry and wet seasons have potentially more fires, as a result of vegetation growth during the wet
season increasing fuel load and consequent flammable conditions during the dry season can lead to
more frequent or more intense fires. Land cover and land use are important because they can affect fuel
load, flammability, number of ignition events, and the conditions under which fires spread. For
example, forests with deep root systems (and therefore access to lower-lying water resources) may take
longer to become flammable during dry periods than vegetation with shallow roots, such as savanna
species. Changes in land use and land cover, including clearance for agriculture and grazing, housing
development, logging and reforestation, land management and habitat fragmentation, can change fuel
load, flammability, number of ignition events, and fire-spread conditions, reducing fuel loads if
biomass is removed or increasing fuel loads when biomass debris is left.

The altered distribution of biodiversity has affected the capacity of ecosystems to regulate fire regimes.
Native species, particularly plants, in areas that are naturally fire-prone are usually fire-adapted so that
ecosystems and ecosystem services are generally not disrupted by fire events. Fires in such situations
are usually relatively limited in extent, short-lived and not very intense, and are less likely to pose an
important hazard. When non-native species become established, either as invasives or because natural
systems are replaced, for example by plantations, fire regimes are likely to be altered. Fires may
become less frequent but much more intense and extensive, posing severe hazards.

Hurricanes and storm surges

Although there have been very few studies that compare the effects of hurricanes across sites differing
in biodiversity, evidence of differences in hurricane resistance between intensively cultivated and less
intensive agricultural systems is available, chiefly from farms in Nicaragua after Hurricane Mitch, in
1998. On average, plots on less intensive farms had more topsoil, higher field moisture, more
vegetation, less erosion and lower economic losses after the hurricane than control plots on more
intensive farms. The differences in favour of such plots tended to increase with increasing levels of
storm intensity, increasing slope and years of low intensity practices, though the patterns of resistance
suggested complex interactions and thresholds.

In coastal areas, mangroves especially have been shown to provide shoreline stability, reducing
erosion, trapping sediments, toxins and nutrients, and acting as wind breaks to buffer against storms.
Following the Indian Ocean tsunami of December 2004, initial reports suggested that communities
living behind intact mangrove forests suffered less destruction than those in places with no natural
protection from the sea. However, it is likely that the magnitude of tsunamis is often such that
mangroves are able to offer limited protection in places receiving the maximum force of the waves, and
other shoreline characteristics are likely to have played a critical role in mitigating the impact of this
particular event in many places. Three factors appear to undermine the ability of mangroves to protect
coastal villages from storm surges and associated flooding: complete clearance, insufficient re-growth
following a previous clearing, and infusion of non-mangrove vegetation. Indeed where mangroves
were present around the Indian Ocean, the key feature of the forests that were most severely damaged
during the tsunami appeared to be a prominence of vegetation not typically found in natural mangrove
forests. Clearly the deeper the mangrove forest from the coast, the more protection that it is able to
offer, and it has been suggested that effective protection against the actions of waves requires at least
100m depth of forest from the shoreline. The extent to which mangroves contribute to protecting
coastal areas against tidal waves and storm surges also depends on other factors such as wave height
and velocity, and coastline topography and orientation. Functioning coral reefs and populations of
coastal trees and shrubs also help minimize wave energy, although there is little evidence to suggest
that coral reef degradation contributed to an increased damage on land following the Indian Ocean

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tsunami in 2004.

Landslides

The frequency of shallow landslides appears to be strongly related to vegetation cover. Tree and other
vegetation roots play an important role in slope stability and can give the soil mechanical support at
shallow depths. The type of vegetation cover is particularly important. For example, evidence from
field studies following Hurricane Mitch in Central America, showed that conventional cross-slope
barriers of grass did little to prevent landslide generation, but deep-rooted trees from the original forest
were more effective. Conversely, deep-seated landslides, with a minimum depth of three metres, are
not noticeably influenced by the presence or absence of well-developed vegetation cover, but most
influenced by geological, topographical and climatic factors.

3.4 Regulation of Infectious Diseases

Although many of the generalities are unknown, there is an increasing body of evidence to suggest
that human health, particularly exposure risk to infectious diseases, depends on the condition of
biodiversity in ecosystems to which people are exposed. The equilibrium among predators and prey,
hosts, vectors, and parasites in an ecosystem provides mechanisms for controlling the emergence
and spread of infectious diseases, and changes to such biodiversity have altered the incidence of
many infectious diseases. There is also strong evidence to suggest that natural systems with intact
structure and characteristics generally resist the introduction of invasive human and animal
pathogens brought by human migration and settlement.

There is an increasing body of evidence to suggest that human health, particularly risk of exposure to
many infectious diseases, depends on the condition of biodiversity in ecosystems to which people are
exposed. Over 60% of human pathogens are naturally transmitted from animals to people, many by
insect and other vectors, suggesting that greater wildlife species diversity sustains greater pathogen
diversity. However, evidence is accumulating that greater species richness at the local scale may in fact
decrease the spread of pathogens to people. Although the actual effect of biodiversity on disease risk is
expected to depend on the nature of interactions between the wildlife host and vector species, such data
are lacking for most such diseases. The following diseases are both significant for poor people
globally, and are highly sensitive to ecological change:

e malaria (across most ecological systems);

e schistosomiasis, lymphatic filariasis, and Japanese encephalitis (particularly in cultivated and
inland water systems in the tropics);
dengue fever (particularly in tropical urban centers);
leishmaniasis and Chagas disease (in forest and dryland systems);
meningitis (in the Sahel);
cholera (in coastal, freshwater, and urban systems).

Risks of other infectious diseases might also depend on the condition of biodiversity, although data to
fully understand such links are sparse and inconsistent. The equilibrium among predators and prey,
hosts, vectors, and parasites in an ecosystem provides mechanisms for controlling the emergence and
spread of infectious diseases, and changes to such biodiversity have altered the incidence of many
infectious diseases. Rabies transmission to people for example has increased in parts of the Amazon
basin following declines in wild vertebrate populations that led to increased vampire bat attacks on

people.

Spread of one disease for which there is considerable data, Lyme disease, seems to be decreased by the
maintenance of natural ecosystems. Although it is not one of the most important diseases amongst poor
people in developing countries, Lyme disease is considered epidemiologically representative of
emerging diseases in general, and can be used as a model system to illustrate some of the effects of
biodiversity change on infectious disease transmission. Lyme disease is the most common vector-

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transmitted disease of people in North America, and thousands of cases occur annually in Europe and
Asia. Studies indicate that the ticks that transmit the disease primarily acquire the pathogen from the
white-footed mouse. A greater number of other small mammal species could reduce the number of
ticks feeding on mice either by reducing mouse abundance through competition, or by attracting ticks
that would otherwise have fed on mice. Indeed areas inhabited by more species of small mammals have
fewer reported cases of Lyme disease per capita. Lyme disease risk is also greater in forest fragments
than in larger forest areas that typically harbour a greater number of mammal species, and also appears
to be related to other variables correlated with mammal species richness, such as climate, geographic
location, and the presence and abundance of specific mammal species.

Human contact with natural ecosystems containing infectious diseases increases the risk of human
infections. However, there is strong evidence to suggest that natural systems with intact structure and
characteristics generally resist the introduction of invasive human and animal pathogens brought by
human migration and settlement. This appears to be the case for a number of disease organisms, such
as cholera, kala-azar, and schistosomiasis, which have not become established in the Amazonian forest
ecosystem.

Different types of ecosystems may contain a unique set of infectious diseases (such as kala-azar or
plague in drylands, dengue fever in urban systems, and cutaneous leishmaniasis in forest systems), but
some major diseases are ubiquitous, occurring across many ecosystems (such as malaria and yellow
fever). Areas of transition between different systems are frequently sites for the transfer of pathogens
and vectors to susceptible human populations such as urban-forest borders (malaria and yellow fever)
and agricultural-forest boundaries (hemorrhagic fevers, such as hantavirus).

ah) Regulation of Climate and Air Quality

The role of biodiversity in climate regulation is most important at the regional and global scale.
Ecosystems exert a strong influence on climate and air quality as sources and sinks of chemicals,
including carbon, and due to the physical properties of vegetation, affect heat and water exchange.
Changes in the relative abundance of different vegetation types, and particularly their structural
diversity, can have significant local effects on wind turbulence and water availability at the more
local scale.

Certain attributes of vegetation, such the characteristics of the dominant species and the distribution of
vegetation in the landscape, influence the capacity of terrestrial ecosystems to regulate climate at the
local, regional, and global scales. Changes in the relative abundance of different plant types (such as
needle-leaved versus deciduous trees, shrubs versus grasses) may have substantial impacts on sources
and sinks of greenhouse gases and on other ecosystem properties, and the structural complexity of
plant canopies also influence water and energy exchange through their effects on albedo. Complex
canopies trap more reflected radiation, thereby reducing albedo. In dense vegetation, albedo is
determined by the properties of the dominant plant types, with albedo decreasing from grasses to
deciduous shrubs and trees to conifers. In open-canopied ecosystems, which account for the majority of
vegetation, all individuals contribute to albedo, and more biodiverse (and hence more structurally
complex) communities have lower albedo.

Large-scale changes in the diversity of vegetation patches in a landscape can have significant effects on
regional climate. Patches that have lower albedo and higher surface temperature than neighbouring
patches create cells of rising warm air above the patch (convection); this air is replaced by cooler
moister air that flows laterally from adjacent patches (advection). Climate models suggest that these
landscape effects substantially modify local-to-regional climate.

Carbon sequestration is affected primarily by species traits, particularly traits related to growth (which
governs carbon inputs) and woodiness, a key determinant of carbon turnover rate within the plant.

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Species diversity can enhance plant productivity through making the most of available resources, and
through increasing the probability of including productive species in the community. Woodiness is
particularly important in enhancing carbon sequestration because woody plants tend to contain more
carbon, live longer, and decompose more slowly than smaller herbaceous plants. However, they also
tend to grow more slowly, and so there is a trade-off among traits of plant species that promote short-
term carbon accumulation versus long-term carbon storage. Plant traits also influence the probability of
disturbances such as fire, wind-throw, and human harvest, which temporarily change forests from
accumulating carbon to releasing it.

The major importance of marine biodiversity in climate regulation appears to be via its effect on
biogeochemical cycling and carbon sequestration. Marine organisms strongly influence the
effectiveness of the biological pump that moves carbon from the surface ocean and sequesters it in
deep waters and sediments. Some of the carbon that is absorbed by marine photosynthesis and
transferred through food webs to grazers, sinks to the deep ocean as fecal pellets and dead cells. The
efficiency of this transfer and therefore the extent of carbon sequestration is sensitive to the species
richness and composition of the plankton community.

3.6 Waste Processing and Detoxification

The processing and detoxification of untreated waste is a particularly important service for the
urban poor. Although very little is known about how many species are necessary to provide
detoxification services or how changes in species composition affect detoxification processes and
rates, these services are likely to critically depend on a small number of specialised species. Plants
and microbes in inland water systems are particularly important. There are clear, although largely
unpredictable, limits to the capacity of ecosystems to undertake detoxification, and these have
frequently been exceeded at the local scale with increasing loads of domestic sewage or industrial

effluent.

The production of wastes is a normal function of all living organisms. Individuals, groups of
organisms, and societies depend on the capacity of ecosystems to detoxify such wastes. Some waste
contaminants (including heavy metals and salts) cannot be converted to harmless materials and will
remain in the environment permanently, but many other contaminants (such as organic chemicals and
pathogens) can be degraded to harmless components, at varying rates.

Although there are thousands of types of materials in wastes, there are two main types of ecosystem
processes that act to reduce the concentrations or impacts of wastes in an environment: processes that
act to change wastes into less toxic forms (i.e. detoxification) and processes that move and transport
wastes (reducing concentrations of waste by diluting them into larger areas or larger volumes of water).
The breakdown of organic chemicals, and loss of their toxicity, is mostly conducted by microbes
(primarily bacteria and fungi) and depends on the type and number of microbes in the total community
that are capable of degrading a particular waste, which in turn depends on prior exposure to the waste.
Some groups of organic chemicals (particularly those not consumed as a food source by microbes) are
especially slow to break down in the environment. For many of these, e.g. Persistent Organic
Pollutants, their resistance to microbial degradation results from the presence of chlorine or bromine,
and breakdown can take years and decades.

Some habitats and species groups play a particularly important role in detoxification and waste
removal. Wetlands are especially important for aquatic waste removal. Wetland plants slow down, trap
and retain suspended sediments and can remove high levels of nutrients, especially phosphorus and
nitrogen commonly associated with agricultural runoff, which could otherwise result in eutrophication
of ground, surface and coastal waters. For example, vegetation along the edge of Lake Victoria, East
Africa, was found to have phosphorus retention of 60-92%. Inland water systems can also export
nutrients. Experimental increases of the species richness of submerged aquatic plant communities have

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resulted in higher algal and total plant biomass, enabling more sediment to be trapped, as well as
greater capture of phosphorus. Experimental work in grasslands also suggests that greater plant species
richness leads to more efficient uptake of nutrients and greater productivity, thereby reducing runoff
loads into neighbouring water courses. The relationship between species richness, species composition
and detoxification can be complex, and less common, less competitive species may play a significant
‘facilitation’ role to other species involved with detoxification processes.

The capacity of wetlands to remove pollutants from chemical or industrial discharges is being
increasingly used as a passive treatment process. For instance, the floating water hyacinth and various
reed species have been used to treat effluents from mining areas that contain high concentrations of
heavy metals. In West Bengal, India, water hyacinth is used to remove heavy metals, while other
aquatic plants remove grease and oil, enabling viable fisheries from ponds that receive significant
pollutants from both industrial and domestic sources.

There are clear limits to the capacity of systems to undertake detoxification, which are largely
dependent on contaminant load. For instance, although metals and persistent organic chemicals can
build up to high enough concentrations to have detrimental effects on the wetland functions, moderate
waste loadings can generally be tolerated by wetlands without loss of services. Moderate loadings of
plant nutrients leads to enrichment (analogous to fertilization of crops), while severe loadings will lead
to a major loss in wetland productivity, structure, and function through eutrophication. The threshold
after which increased loadings significantly damage the capacity of wetlands to detoxify wastes is not
easily determined and depends on the specific conditions in each wetland.

Sh Nutrient Cycling

Nutrient cycles — the flow of nitrogen, phosphorus, sulphur, potassium and a range of other
elements — within the biosphere are an essential part of living processes. These cycles are mediated
by a range of different organisms, including those that extract nutrients from inorganic sources,
such as nitrogen-fixing bacteria, and decomposers, that recycle nutrients from dead organisms or
waste products, incorporating them into other living systems or returning them to inorganic form.
Many nutrient cycles have been heavily modified by people, usually through large increases in the
supply of nutrients (e.g. by industrial fixation of nitrogen and the application of agricultural
fertilizers). While this has greatly increased primary productivity in many areas, as nutrients are
required for plant growth, it has created widespread and major problems through increasing
nutrient load in downstream systems beyond the capacity of these systems to cope effectively. This
can lead to a deterioration or complete loss of ecosystem services, such as collapse of inshore or
inland water fisheries, which may be of particular value to local communities.

Nutrients, such as nitrogen, phosphorous, sulphur and potassium are essential for organisms to grow
and develop, and an adequate and balanced supply of nutrients underpins all other ecosystem services.
Ecosystems regulate the flow of nutrients through a number of different processes, which allow these
elements to be extracted from water, air and soil, or recycled from dead organisms. This service is
supported by a diversity of different species. Human activity, largely agricultural use of fertilizers and
other industrial processes, has resulted in a doubling of the rate of creation of available nitrogen on the
land surfaces of Earth. While in some areas (notably parts of sub-Saharan Africa) shortage of nitrogen
still limits agricultural productivity, in much of the rest of the world its use is inefficient, with excess
often applied. This increase in nitrogen on land and in surface waters has resulted in increasing food
production in some countries, but at the cost of frequent deterioration in freshwater and coastal
ecosystem services, such as water quality, fisheries and amenity values.

Eutrophication (inadvertent nutrient enrichment) has commonly resulted in thresholds of change in

surface waters, with widespread algal blooms and anoxic zones — regions where the level of dissolved
oxygen is too low to support most or all oxygen-breathing organisms. Phosphorus, the use of which

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tripled between 1960 and 1990, has similar impacts. Although agricultural fertilizers are the main
cause of nutrient loading, human and animal waste are also important causes of nutrient enrichment in
inland and coastal waters. Untreated sewage not only causes eutrophication, but is also a major health
hazard because of the likely presence of various kinds of pathogens.

Although the diversity of plants and soil invertebrates may influence nutrient cycling and regulate
nutrient flow between ecosystems, the generality of this process has not yet been demonstrated, and the
underlying mechanisms have not been clearly identified. However, experimental studies have shown
with high certainty that a decline in species richness results in more variable soil nitrogen levels, and it
is clear that the presence of certain functional groups of species is the most important factor in
determining biodiversity effects on nutrient cycling. For example, decomposers play a strong role in
moving nutrients from organic matter into the soil and water, and mycorrhizal fungi play a particularly
critical role in enhancing the availability of soil and water nutrients to plants.

Whilst nitrogen is transferred through cycles at a global scale, returning to the land via atmospheric
pathways from the ocean, phosphorous typically flows from terrestrial to marine systems, only
returning to land over geological timeframes through ocean sedimentation. However, at a very local
scale some animals play a key role in returning both nitrogen and phosphorous from marine to
terrestrial and freshwater systems. Sea birds, and some marine mammals and fish move nutrients from
food sources in the sea to the land and into inland waters via excretory processes, and mortality, either
in coastal areas, or further inland as a result of migration pathways.

3.8 Medicines

The widespread reliance of the poor on natural medicines is met largely through the use of locally
harvested plant extracts. Other species groups are used infrequently. In addition to the direct benefit
from medicinal plants, medicinal benefits from manufactured drugs have historically been largely
dependent on extracted biodiversity. Such benefits have largely derived from high diversity
ecosystems, although active ingredients have also been sourced from low diversity systems, where
they have often arisen as a response to harsh environmental conditions.

Traditional medical systems are important globally, and particularly for the world’s poor, who have
restricted access to formal medical care. Natural medicines are often the only source of medicine
accessible by poor people, and can help alleviate the national costs of supplying medical provisions in
many developing countries. An estimated 2000 tonnes of herbs are used annually in India, and the ratio
of traditional healers to western-trained doctors reaches 150:1 in some African countries. Many
countries, such as Thailand, Sri Lanka, Mexico, and China and India, have integrated traditional
medicine into their national health care systems. There is also a very large and expanding commercial
trade in medicinal plants, involving an estimated 2,500 species. In addition to the direct harvest for
traditional medicines, biodiversity also provides both information and raw materials that underpin
medicinal and health care systems worldwide in the formal sector. More than half the world’s modern
drugs are derived from biological resources.

About 85% of traditional medicine involves the use of plant extracts. Although the number of plant
species that have been used for medicinal purposes is not known accurately, it is estimated that current
use exceeds 50,000 species, including almost 20% of the Chinese flora, around 7,000 species in India,
and some 10% of Indonesia’s flora. The use of other groups in traditional medicine is infrequent, and
poorly documented. Estimates of the number of marine species used for medicinal purposes ranges
from a few hundred to a few thousand, the use of which is mainly confined to Asia.

As a result of their relatively high biodiversity and the knowledge of this held by traditional cultures,

forests, particularly tropical rainforests, have provided many important medicinal drugs used in the
developed world. This is despite the fact that only 5 -15% of higher plant species have been

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investigated for the presence of bioactive compounds. Some low biodiversity habitats, such as
drylands, produce very valuable medicinal and aromatic plants, where the active ingredient(s) is often a
chemical response to living under harsh environmental conditions (e.g. chemicals which provide some
tolerance to drought, high-salinity soils, extreme temperatures, etc).

The future ability of poor people to benefit from natural medicines is likely to be threatened by the loss
of local populations of species. Supplies of wild plants in general are increasingly limited by over-
harvesting and loss of forest cover. In Eastern Amazonia, for example, where native plants provide
most of the medicines used locally, logging of trees that supply medicinal leaves, fruits, bark, or oils
has critically diminished the supply of medicines required by both the rural and the urban poor.
However, while forest loss or degradation tends to reduce the availability of medicinal resources, not
all species are affected in the same way by harvesting pressures, and a few useful species thrive in the
secondary growth that follows timber extraction.

The number of medicinal and related species currently in formal cultivation for commercial production
does not exceed a few hundred world-wide, although many more species, especially the aromatic
herbs, are cultivated on a small-scale in home gardens. Globally, about 75% of all botanical species in
trade continue to be sourced from the wild. Increasing disease resistance to some medicinal compounds
is likely to result in alternative sources of plant-derived medicines becoming increasingly important.

3.9 Timber, Fibres and Fuel

The availability of timber, natural fibres and woodfuel on which poor people depend is largely
determined by the distribution and abundance of particular forest and woodland species. Some such
species require intact forest habitats in order to thrive, whilst others grow outside of wooded areas,
and some are widely cultivated. Limited available evidence suggests that the productivity of timber,
fibres and fuel from wooded areas is enhanced with increasing species diversity, particularly on
marginal land.

For timber and fibre production, the presence of specific species and combinations of species, rather
than the diversity of the forest area or agricultural area per se, is the most important factor at any
particular locality. The timbers of individual tree species, for example, possess different properties that
render them suitable for different purposes. Production of woodfuel from natural areas is less species-
dependent, although there are certainly preferred species that generate more heat or better quality
charcoal. Most studies of the relationship between timber, woodfuel or fibre production and species
diversity have centred on commercial plantations or compared plantations of varying species richness
with neighbouring natural forest. In general, forests of two species are more productive than single
species stands, but they are not necessarily more productive than the best monoculture. Inhibitory and
enhancing effects of particular species and combinations of species are common.

Few studies have compared primary production of forests over a wide range of species richness.
Studied forests in the US and in the western Mediterranean show a positive correlation between tree
species richness and stand productivity, some of which has been explained due to greater leaf litter
production in mixed forests, a key process in nutrient cycling. However, positive effects beyond two-
species mixtures largely depend on the species and functional identity of the dominant tree species.
The enhanced timber and woodfuel production from more diverse forests has also been attributed to
several factors including: lower levels of pest damage and stem rot; higher resistance to invasive
species; species differences in height (rather than diameter) growth, form, and shade tolerance; more
efficient nutrient use (due to species differences in rooting patterns, mycorrhizal associations and
nutrient demands); and ‘nurse’ species providing structure beneficial to primary crop species, e.g.
training, shade, or protection from frost or drought. Overall, although the lack of long-term monitoring
of diverse sites limits the ability to assess the relative importance of composition versus number of tree
species on timber, woodfuel and fibre productivity, diverse forests tend to outperform monocultures on

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poor sites, but pure stands of a highly productive species can have higher merchantable yields on high
quality sites.

Despite the importance of forest patches for the local supply of timber, fuel and other services to poor
people, rates of deforestation during the last four decades has been highest in tropical forests in Africa,
Southeast Asia, and South America. In addition to changes in land use, habitat fragmentation has a
significant impact on forest structure and species composition, including those important for the supply
of timber, fuel and fibre. Forest fragments are ecologically different from intact areas, and are also
influenced by “edge effects” — ecological changes associated with the artificial abrupt margins of
habitat fragments. New plants growing near forest edges tend to be small disturbance-tolerant pioneer
and secondary species rather than old-growth, forest-interior species. Large canopy and emergent trees,
which contain a large proportion of forest biomass are particularly vulnerable to fragmentation.

3.10 Cultural Services

Cultural, amenity and spiritual services provided by ecosystems are highly valued by the poor, and
play a key role in medium to long-term sustainable development strategies. Indeed cultural diversity
itself has been affected by the distribution of biodiversity. Cultural ecosystem services generally
depend on the importance of particular cultural relationships with various features of the landscape,
such as particular stands of forests, and with specific components of biodiversity, such as particular
revered species. The vast majority of formal religions and belief systems have clear links to the
natural world, although the impact of the loss of particular attributes of biodiversity on many
cultural services is not clear.

There is a tendency to dismiss, or at least attach little importance to, the non-material services provided
by biodiversity when addressing the needs of the poor. And yet these aspects — cultural, amenity and
spiritual —are evidently highly valued by many of the non-poor. This is manifested in the environments
that the latter usually choose to live in when given the opportunity — rich in gardens, parks and other
green spaces. Such environments undoubtedly increase the quality of life of the people who inhabit
them. Not only is there every reason to assume that they would do the same for poorer people if they
had the opportunity to experience them, but recent studies at the local level have in fact demonstrated
the importance of cultural services to poor people®. Although when poverty reduction is dealing with
extreme levels of absolute poverty there are likely to be other short-term priorities, when development
is dealing with longer-term goals, the cultural benefits that are derived from biodiversity should be a
major factor to be considered.

The varied distribution of biodiversity has contributed directly to cultural diversity itself, and visa
versa - cultural practices have significantly shaped the patterns of biodiversity distribution at local and
regional scales. The various cultural and amenity services provided by ecosystems include: cultural
identity (that is, the current cultural linkage between people and their environment); heritage values
(‘‘memories’’ in the landscape from past cultural ties); spiritual services (sacred, religious, or other
forms of spiritual inspiration derived from ecosystems); inspiration (the use of natural motives or
artefacts in arts, folklore, and so on); aesthetic appreciation of natural and cultivated landscapes; and
recreation and tourism. The capacity of an ecosystem to supply cultural and amenity services is partly
determined by the physical and biotic environment (such as the presence of landscape features with
scenic, inspirational, or sacred values), and partly by culture. Thus similar environmental features
(particular species, forests, soil, waterfalls, landscapes, and so on) will be perceived, experienced and
valued differently by different societies, depending on the cultural background and the way societies
have shaped their environment during the course of their development. Cultural and amenity services
are of direct importance to human well-being in terms of improved physical and mental health and
well-being, and can represent a considerable economic resource, for example in the case of tourism.

3 See the Millennium Ecosystem Assessment sub-global assessments, information on which is available from
www.MA web.org

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Cultural identity, including different knowledge and value systems, is integral to most people’s lives,
even if not consciously recognised, and maintenance of cultural heritage is an important service of
many semi-natural and cultivated ecosystems and landscapes. At the global level, initiatives have
emerged to conserve culturally important landscapes directly - through, for example, UNESCO’s Man
and Biosphere Reserves and World Heritage Sites, FAO’s Globally Important Ingenious Agricultural
Heritage Systems, and WWF ‘Sacred Gifts to the Earth’ initiative.

Most people feel the need to understand their place in the universe, and they search for spiritual
connections both to and through their environment, through personal reflection, and through more
organized experiences (as part of religious rules, rituals, and traditional taboos, for example). This is
reflected by spiritual values placed on certain ecosystems (such as ‘‘holy”’ forests), species (sacred
plants and animals, for instance), and landscape features (such as mountains and waterfalls). The
spiritual connections between people and the earth are often a reflection of traditional views on nature
— they are also integral parts of ethnic identity, particularly among indigenous peoples, and the most
common element of all religions throughout history has been the inspiration they have drawn from
nature, leading to a belief in non-physical beings. The concept of the ‘‘sacred grove’’ that traditionally
served as an area for religious rituals to appease nature-linked deities as well as a site of worship for
ancestral spirits can be viewed as symbolic of the spiritual services derived from ecosystems and
illustrates the long importance of components of biodiversity in humankind’s cultural evolution. These
sites can be very numerous — for instance, there are estimated to be between 100,000 and 150,000
sacred groves in India alone.

Sacred species, habitats and landscapes, often also have other values. Indeed most sacred groves are
also sources of food, or fuel, e.g. the tembawang groves of the Dayak people in Kalimantan, Borneo
are simultaneously burial sites and fruit gardens. In providing focal points for social and cultural
celebrations and religious rituals, sacred natural sites also help establish and maintain social cohesion
and solidarity within communities.

Natural and cultivated systems inspire an almost unlimited array of cultural and artistic expressions,
from books, paintings and sculptures, to folklore, music and dance, and even architecture. Natural
environments are also an important source of aesthetic pleasure for people all over the world, including
the poor. A great number of studies in environmental aesthetics have shown that people display, in
general, a strong preference for natural over built environments and this has been observed across all
times and cultures. Numerous studies have demonstrated that contact with nature may enhance
recovery from stress and increase physical and mental health and well-being, as well as conferring
social benefits, such as decreased levels of aggression and criminality and increased social integration.
In general, people prefer natural settings that are healthy, lush, and green. Verdant vegetation is
preferred over arid landscapes.

The culture of many traditional societies is particularly based on extended associations with
ecosystems, a reflection of which is a deep empirical knowledge about local natural resources,
especially food and medicines, and a wealth of language for describing these items and associations.
Indeed, language, knowledge, and the environment have been intimately related throughout human
history and approximately two thirds of the world’s languages are linked to forest-dwellers, with
almost 50% of all languages spoken in tropical/sub-tropical moist broad-leaved forest biomes. The
clearance of tropical forest regions has resulted in social breakdown and forced emigration of
traditional groups (for example in Indonesia, Brazil and elsewhere), and reduced cultural diversity.

There are very few documented examples of the effects of decline or loss of biodiversity on cultural
and amenity service provision. However, customs and beliefs that have long prevented problems of
overexploitation of natural resources have softened, traditional knowledge systems have been lost, and
numbers of sacred sites and populations of sacred species have declined globally. This has a particular
impact in traditional societies, such as shifting agricultural societies in the tropics where there can be
major economic as well as social consequences. The gradual change from direct and participative

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experience of nature (through all senses) to its virtual representation through the media is hard to
describe, let alone quantify. The loss of particular ecosystem attributes (e.g. sacred species and forests),
combined with social and economic changes, can sometimes weaken the spiritual benefits people
obtain from ecosystems. On the other hand, under some circumstances, the loss of some attributes may
enhance spiritual appreciation for what remains.

Invasive species are also becoming a major issue in the maintenance of cultural and amenity services in
different parts of the world. Studies suggest that invasions by exotic species can have a strong impact
on land transformations and land degradation and affect traditional livelihoods as well as cultural and
spiritual well-being, particularly the poorer sections of rural society in the developing tropics.

4 Conclusions and Implications for Policy

The overarching focus of the current development agenda is enshrined in the Millennium Declaration,
and embodied in the Millennium Development Goals, which establish a framework for progress
towards the Millennium Declaration. Much of the work relating to biodiversity within the context of
development agencies has been guided by three principles: the overriding priority of poverty
elimination; sustainable development, and; the precautionary principle. The last of these has been
defined by the UK Department for International Development as follows: ‘Where there are threats of
serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for
postponing cost-effective measures to prevent environmental degradation.’ Although in practice the
precautionary principle has proved difficult to implement, considerable analysis of approaches and
practices has been undertaken in recent years resulting in guidelines for its more effective
implementation.

e Poverty elimination

In considering the extent to which development agencies should concern themselves with biodiversity
in all its various aspects it is important to distinguish between situations where the objective is the
immediate and urgent relief of absolute levels of poverty (effectively disbursement of humanitarian
aid) and those where the aim is longer-term, planned development to lift people permanently out of
poverty and enable them to lead lives with a large degree of freedom and choice. In the former case
environmental concerns are, understandably, likely to be accorded lower priority, although the effect of
this will often be simply to defer problems associated with environmental management. Certainly
where options are available, humanitarian interventions with the least impact on local and landscape-
scale biodiversity are likely to lead to a stronger foundation for medium to longer-term development.
In the latter case, where the majority of development agencies see the focus of their activities, there are
compelling reasons why consideration of biodiversity at the landscape scale, and the benefits it
provides in the form of ecosystem services should be fully incorporated into mainstream
development planning.

e Risk and local diversity

The poor typically need to adopt short-term planning horizons. They by definition accumulate few
reserves and are therefore vulnerable to both foreseeable and unpredictable changes in their situation.
Such changes may be lead to shortages of basic goods and necessities, such as food, drinking water,
shelter, clothing, medicines, fuel and sanitation. The rural poor in particular usually obtain these
services locally, and may be heavily dependent on the diversity and integrity of the environment within
the immediate landscape for a continued supply. Although the precise conditions vary enormously
from place to place, the range of needs of the poor is most likely to be met through a diverse mosaic
of more or less intensively managed systems, including agricultural lands, pasture, wood-lots or

forests, and aquatic systems.

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However, use of resources from these systems is often not sustainable, or is threatened by external
factors and forces leading to environmental degradation, deterioration in quality of life for those
concemed, and increased exposure to risk. Traditional responses to this involve attempting to increase
economic activity (often at national or regional level) from alternative livelihoods, with the intention
that the poor will ultimately have more money at their disposal and will be more able to buy in
substitutes from elsewhere for those resources that had previously been supplied locally. Increasing
economic activity normally involves intensification of production associated with simplification of
production systems, conversion of natural or semi-natural systems to artificial ones, higher inputs and
increasing exposure to and dependence on global markets, both as a source of income through selling
the commodities produced, and a source of goods to be bought.

It is very doubtful that these changes are always to the benefit of the poor in those places where they
take place. One important reason for this is that they reduce the capacity of the local area to meet the
needs of the local population, increasing dependency on the vagaries of markets, from regional to
global in scale. With increasing globalisation, such markets are extremely vagile, always seeking the
lowest-priced supply, so that producers in any given area are very vulnerable to being under-cut and
losing market share. Because of this, producers often try to maximise short-term returns, usually
leading to accelerated rates of environmental degradation, and eventually leaving local people in the
position where they have neither the capacity to produce commodities for sale nor a local resource base
to fall back on.

The medium and long-term interests of the poor are likely to be best served by the maintenance of a
diverse resource base at the landscape (i.e. accessible) scale, at the very least as a vital risk-
mitigation measure. This does not, of course, mean that all forms of intensification and adoption of
new technologies should be avoided — far from it. Judicious application of new technologies and
techniques, use of improved varieties (not necessarily excluding those developed with gene transfer
technologies) in agriculture, and appropriate levels of inputs such as nitrogen and phosphate-based
fertiliser, can increase productivity and help towards eliminating poverty. Increasing the efficiency of
use of existing agricultural lands can actually reduce environmental degradation by reducing the
incentive to convert marginal lands. The key is that such development should not be at the expense of
the existing natural resource base and should be planned to ensure delivery of medium and long-term
benefits, rather than maximising short-term gains. This suggests that the most successful long-term
poverty elimination strategies would, for example, include supporting agroforestry and multicropping
rather than monoculture commodity production, use of integrated pest management techniques rather
than intensive blanket applications of pesticides, encouragement of sustainable fisheries practices and
so forth.

Although various ecosystem services are often presented as discrete benefits, it is of course the
multiple benefits that people derive from biodiversity that are important. Human well-being is
dependent on benefits not just of individual services such as food, or clean water, or waste processing,
but combinations, or “bundles” of services. The relative importance of services within such bundles
depends on both attributes of the local environment (including climate, topography, and human
population density), and wealth (ability to substitute various ecosystem services with technologies). In
considering the dependence of ecosystem services on biodiversity, it is therefore necessary to consider
the full range of ecosystem services from which people benefit. Typically for poorer people, this range
is wider, both because of the restricted access to substitutes, and because of lack of security in terms of
land tenure and access to resources, reliance on more marginal lands, and reduced protection from
natural hazards.

e Global and local values of biodiversity

Confusion exists between the different kinds of value that are attached to biodiversity and the different
levels at which these are important. At global level, many people consider existence value important.
This is a major impetus for conservation and is manifested most clearly in the attempt to prevent
species going extinct and to preserve unique or representative habitats and ecosystems in Protected
Areas. Poor people living in places where species are at risk of going extinct or where loss of habitats

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and ecosystems is proceeding most rapidly are generally less able to implement existence values
(although it is not true to say that they attach no importance to such values, and in some circumstances
they may value existence of particular aspects of biodiversity quite highly). It is widely argued that
under these circumstances local people, usually poor, are expected to bear a disproportionate amount of
the costs of conservation. This is undoubtedly often true (although a mechanism theoretically exists
through the Global Environment Facility for this to be corrected). However, it is also often true that
there may be strong convergence between the longer-term interests of the local poor and those
whose concern is global, conservation benefits. This is because the presence somewhere of a
significant number of threatened species or rapidly disappearing habitats generally signals
unsustainable use of a particular resource. A classic example is the small forest areas, high
deforestation rates and large numbers of threatened species on many tropical islands. Reduction in
deforestation rate and sustainable management of remaining forest areas is almost always in the longer-
term interest of the local poor and of conservationists, even if for somewhat different reasons.

e International obligations

A number of important multilateral environmental agreements are directly concerned with or have
implications for biodiversity. The most important of these is the Convention on Biological diversity
(CBD). Others include UN Framework Convention on Climate Change (UNFCCC), the UN
Convention to Combat Desertification (UNCCD), the Ramsar Convention on Wetlands, the
Convention on International Trade in Endangered Species (CITES) and the Convention on Migratory
Species (CMS). Parties to these various conventions are bound by obligations under these agreements.

Box 3. The Convention on Biological Diversity (CBD): Implications for development policy

In the case of developed countries, obligations under the CBD fall into two main categories:
domestic obligations — that is within-country implementation of the substantive Articles of the
Convention, to ensure that the Convention’s objectives are met at home; and provision of
assistance to developing country Parties to enable them to meet the Convention’s objectives. Such
assistance is expected to take the form of co-operation, provision of new and additional financial
resources and transfer of technology, including through the Global Environment Facility, which
operates the financial mechanism under the CBD. Development agencies are well placed to assist
developing country partners in their implementation of the CBD, through the multilateral GEF
mechanism, bilaterally and through regional associations and partnerships.

Almost all the substantive Articles of the CBD are relevant to the work of development agencies

and should be taken into account in policy implementation. Some of the most pertinent are:

e Mainstreaming of biodiversity (Article 6)

e Incorporation of biodiversity concerns into other sectors (Article 6)

e Respect, preserve and maintain knowledge, innovations and practices of local and indigenous
communities (Article 8(j))

Cooperate in providing financial and other support for in-situ conservation of biological diversity
to developing countries (Article 8 (m))

e Ensuring that use of the components of biodiversity is sustainable (Article 10);

e Carrying out impact assessments for all activities to ensure that they do not have an adverse
impact on biological diversity (Article 14)

e Provision to developing countries of the technology needed to implement the Convention under
fair and most favourable terms (Article 16)

e Provision of new and additional financial resources to enable developing country Parties to meet

their obligations under the CBD both through the GEF and by bilateral and other means (Article

20)

An important challenge for development agencies in this arena is to identify significant gaps in
policy implementation by governments and to develop mechanisms for filling these gaps.

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Parties to the CBD (of which there are 188) are bound by obligations under that Convention, whose
objectives are: the conservation of biological diversity, the sustainable use of the components of
biological diversity and the equitable sharing of the benefits arising from the use of genetic resources
(see Box 3). Developed country Parties have agreed not merely to meet these objectives at home, but
also to provide the additional resources necessary to enable developing countries to meet them. At the
very least, therefore, it is incumbent on government agencies and departments to ensure that their
activities do not conflict with the objectives of the CBD. Similarly, Parties having ratified the Kyoto
Protocol of the UN Framework Convention on Climate Change (UNFCCC), and undertaken to reduce
their own greenhouse gas emissions, would be inconsistent to support or promote activities in other
countries that would result in an increase in such emissions.

e International policy implications

It is important that national development agencies continue to build on partnerships with other
government departments to ensure that the governments present coherent and consistent policies
regarding biodiversity and poverty in all policy arenas. This involves not merely developing a
harmonised position in the different multilateral environmental agreements but also ensuring that
obligations under these are reflected in other arenas, such as OECD and WTO. With regard to the
latter, the relationship between the livelihoods of the poor, trade barriers and subsidies and incentives is
not straightforward. For example, removal of trade barriers will not necessarily benefit the world’s
poorest people if it leads to a significant deterioration in the local ecosystem services on which they
depend, even if it leads to some increase in national economic activity in the countries in which they
live. In contrast, removal of perverse (environmentally and socially damaging) incentives is on the
whole likely to benefit poor people. For example, reduction in subsidy to industrialised fisheries will
generally be of great benefit to poor fishers, as it will lead both to increasing fish stocks and decreasing
competition for those stocks. Pro-poor policies in these areas would benefit from taking more fully into
account the ecosystem services on which poor people depend.

Ensuring environmental sustainability is one of the eight Millennium Development Goals. It does,
additionally, underpin all the other goals — without it, elimination of poverty will only be at best
temporary and at worst illusory. However, the central role that this goal plays in long-term poverty
elimination is not well reflected in the current choice of targets or indicators for it, and there is
considerable opportunity for the revision of these so that they more fully reflect the fundamental
importance of this goal, including closer alignment of the indicators with those adopted in the CBD, in
relation to the 2010 biodiversity target.

e Influencing policies and institutions at the national level

Many development agencies are well-placed to help partner governments harmonise their various
strategies and action plans, including sectoral plans, poverty reduction strategies, national strategies for
sustainable development, national environmental action plans and national biodiversity strategies and
action plans. This would help identify inconsistencies and gaps and ensure that they take into account
the needs of the poor, reflecting the value of diverse ecosystem services, and would entail encouraging
the adoption of participatory, bottom-up planning and of a people-centred ecosystem approach, as
agreed under the CBD.

As part of this, systems of tenure and access to resources are needed that are equitable and that
promote the sustainable use of natural resources through long-term management. Full
environmental impact assessments for all projects, and the adoption of strategic environmental
assessments for all plans and strategies would also contribute enormously to ensuring ecosystem
services are more fully incorporated into development planning. Such assessments should address both
global biodiversity concerns (e.g. impact on threatened or unique species or ecosystems) and the need
to maintain provision of diverse environmental services for poor people. The sharing of information
made available from environmental assessments and other processes with development practitioners
and governments is much needed. Information sharing within and between governments, including

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that of government-funded science, would greatly assist in the development of appropriate
development and environmental policies.

Box 4. Questions arising for consideration by development agencies in light of these policy

implications

e Are effective mechanisms in place to ensure that all development activities are in conformity
with national obligations under the CBD and other environmental agreements?

e Are effective mechanisms in place to ensure coordination and sharing of information at the
national level within government on policies and practice related to ecosystem services and the
poor?

e Do development agencies have effective mechanisms in place for assessing the extent to which
programmes and policies of partner governments are in conformity with Millennium
Development Goal 7 (ensuring environmental sustainability)? Are effective strategies in place
for assisting governments to implement MDG7 fully?

e What are the implications of the important links between biodiversity and ecosystem services
for budgetary support and other emerging aid instruments?

e How effectively do current environmental assessment processes (SEAs and EIAs) deal with
biodiversity? Are suitable criteria developed and used to determine that programmes and
projects at minimum do no harm?

e Are effective mechanisms in place for monitoring the impact of projects and programmes on
ecosystem services, and assessing the effects of any impacts on livelihoods?

e How can the risks to the poor of biodiversity loss be appropriately assessed? Do such
assessments take into account the full range of ecosystem services on which poor people
depend?

e Are specific policies in place for promoting both integrated environmental management at the
landscape level, and low-impact agricultural practices, including integrated pest management?

e Are effective mechanisms in place for disseminating best practice in natural resource
management?

e Influencing policies and planning at the regional level

Development agencies should encourage management and planning practices that maintain or
restore environmental heterogeneity at the landscape level. This is the simplest way to ensure that
poor people have access to the range of ecosystem services that they need while at the same time
allowing individuals or families to manage their own resources (eg. farm-plots in agricultural systems)
in the ways that most suit them. This approach is precautionary in that it does not call for a detailed
understanding of the precise role that biodiversity plays in providing different services from the various
ecosystems but simply recognises that a diverse array of systems is most likely to supply a diverse
array of services. It should not impose excessive costs on individuals, as it does not expect them to
maintain on their plots systems from which they cannot derive immediate benefit.

Although integrated landscape planning is the best way to ensure continuing provision of ecosystem
services (and is reflected in the ecosystem approach of the CBD), operationally it is difficult to put into
practice because governments are generally organised by sector. Experience in integrated coastal zone
management, where such practices tend to be most advanced, indicate that multi-stakeholder plans and
information sharing can be successfully developed (eg. in the Tanga region of Tanzania, and in Belize),
but that it is then difficult to establish a legislative framework for implementation of plans and
strategies. A key challenge for development agencies is to find ways of overcoming this obstacle.

e Influencing activities at the community, farm or individual level
The adoption of low-impact management practices should be encouraged in production systems
where these can be shown to deliver significant on-site benefits. Two important examples are the use

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of integrated pest management techniques and commercial production of environmentally-friendly
goods. Integrated pest management has been shown to deliver both immediate economic benefits
(lower input costs for the same or enhanced yields) and wider environmental and health benefits (eg.
reduced water pollution, reduced adverse health impacts from exposure to pesticides). Barriers to
adoption of such techniques are often to do with lack of knowledge and/or entrenched customary
practices. Markets for value-added environmentally friendly goods are growing, chiefly in developed
countries but also amongst wealthier consumers in developing countries. Poor producers, however,
often have difficulties in accessing such markets, particularly where they are based on independent
certification schemes. Development assistance can be very valuable in helping overcome such barriers,
and in developing other innovative ways of benefiting from the global values of biodiversity through,
for example, low impact tourism.

Where programmes are planned that encourage exploitation of previously unharvested resources, or
increase levels of exploitation (for example through the opening up of outside markets) it is crucial that
a thorough assessment is first made of the possible impacts on the resource. In this instance, a
precautionary approach calls for an analysis of the possible collateral impacts on other ecosystem
services of such exploitation.

Where the livelihoods of poor people already depend on or involve the harvest of wild resources (such
as timber and non-timber forest products from natural or semi-natural forests, capture fisheries, or
bushmeat), at a minimum efforts should be made to try to ensure that the harvest of resources is
sustainable at the local level. This may entail: assistance in the establishment of adequate and
appropriate tenure regimes; development of monitoring regimes and setting and enforcement of harvest
limits (eg. closed seasons, harvest quotas); and adoption of non-destructive or low-impact harvest
techniques. Such approaches may also be viewed as precautionary as they do not require a complex
understanding of the impacts of harvest on non-target populations and ecosystems to be justified.
Although it is in principle not difficult to plan such approaches, developing effective intervention
mechanisms has proven challenging. Development agencies could play an extremely useful role in
widely disseminating best practice from their work in natural resource management.

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Annex — Glossary and acronyms

Advection: The transport of an atmospheric property (e.g., temperature) by the wind

Albedo: A measure of the degree to which a surface or object reflects solar radiation.

Anoxic zone: An environment devoid of oxygen

Benthic zone: The oceanic zone that encompasses the sea-floor and the organisms living in or on it.

Biocide: A chemical with the capacity to kill living organisms e.g. pesticides, herbicides.

Biodiversity (a contraction of biological diversity): The variability among living organisms from all sources,
including terrestrial, marine, and other aquatic ecosystems and the ecological complexes of which they are
part. Biodiversity includes diversity within species, between species, and between ecosystems.

Biogeochemical cycling: A natural process in which elements are continuously cycled in various forms between
different compartments of the environment (e.g., air, water, soil, organisms).

Biomass: The mass of tissues in living organisms in a population, ecosystem, or spatial unit.

Biota: All living organisms of an area.

Boreal forest: Forests of pine, spruce, fir, and larch stretching from the east coast of Canada westward to Alaska
and continuing from Siberia across the entire extent of Russia to the European Plain.

Co-metabolite: An enzyme produced by microbiological metabolism that aids degradation of a contaminant

Carbon sequestration: The process of increasing the carbon content of a reservoir other than the atmosphere.

CBD: Convention on Biological Diverstiy

Decomposition: The ecological process carried out primarily by microbes that leads to a transformation of dead
organic matter into inorganic mater.

Denitrification: The process by which nitrates are converted to ammonia and molecular nitrogen by denitrifying
bacteria in the soil.

Ecolabelling: A voluntary method of certification of environmental quality (of a product) and/or environmental
performance of a process based on lifecycle considerations and agreed sets of criteria and standards.

Ecosystem: A dynamic complex of plant, animal, and microorganism communities and their non-living
environment interacting as a functional unit.

Ecosystem process: An intrinsic ecosystem characteristic whereby an ecosystem maintains its integrity.
Ecosystem processes include decomposition, production, nutrient cycling, and fluxes of nutrients and
energy.

Ecosystem services: The benefits people obtain from ecosystems. These include provisioning services such as
food and water; regulating services such as flood and disease control; cultural services such as spiritual,
recreational, and cultural benefits; and supporting services such as nutrient cycling that maintain the
conditions for life on Earth. The concept “ecosystem goods and services” is synonymous with ecosystem
services.

Edge effects: ecological changes associated with the artificial abrupt margins of habitat fragments

Efficacy: a measure of the benefit resulting from an intervention for a given health problem under the ideal
conditions of an investigation

EIA: Environmental Impact Assessment

Eutrophication: The increase in additions of nutrients to freshwater or marine systems, which leads to increases
in plant growth and often to undesirable changes in ecosystem structure and function

Evapotranspiration: see Transpiration

Exotic (alien) species: Species introduced outside its normal distribution

FAO: Food and Agriculture Organisation (of the United Nations)

Food Web: The complex patterns of energy flow in an ecosystem, summarised by the known feeding
relationships in a biological community. A food web illustrates how each type of organism in a
community is typically consumed by or consumes more than one other type of organism, and that different
types of organisms compete for the same food sources.

Fuel load: the amount of combustible material available for burning generally referring to dry herbaceous
material or leaf litter (fine fuel).

Functional diversity: The value, range, and relative abundance of traits present in the organisms in an ecological
community.

GEF: Global Environment Facility

Germplasm: The genetic material, especially its specific molecular and chemical constitution, that compromises
the inherited qualities of an organism.

Herbivore: An animal that only eats live plant matter

Heterogeneity: the quality of being diverse and not comparable in kind Genetic heterogeneity refers to diseases,
conditions or other characteristics that appear similar but whose genetic basis is different in different

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populations or individuals. Habitat heterogeneity: the degree of variability and patchiness across a
landscape at a given scale.

Heterotrophic: an organism, such as an animal or fungi, that cannot synthesize its own food and is dependent on
complex organic substances for nutrition (antonym- autotrophic: an organism (green plant) that can make
complex organic nutritive compounds from simple inorganic sources by photosynthesis)

Host a living organism that serves as a blood source for blood-feeding arthropods, or on which a parasite lives

In-situ conservation: The conservation of ecosystems and natural habitats and the maintenance and recovery of
viable populations of species in their natural surroundings and, in the case of domesticated or cultivated
species, in the surroundings where they have developed their distinctive properties.

Invasive species: A species whose establishment and spread modifies ecosystems, habitats, or species.

Landrace: Locally bred and adapted varieties of crops

Leaching: The loss of soluble material such as nutrients or toxins from the soil.

MA: Millennium Ecosystem Assessment (www.MAweb.org)

Macrofauna: an animal whose shortest dimension is greater than or equal to 0.5 mm

Mesocosm: A field-scale model utilized to understand the interactive relationship of microbial communities and
the roles played by microbial populations within ecosystems. For example, a sediment sample contained in
an opened vessel and placed on a riverbed or in a flow-through system in a laboratory (not temperature
controlled as it should simulate outdoor temperatures).

Microbe: Microscopic organism, such as a bacteria, virus or protozoa

Microcosm: A laboratory-scale model used to understand the interactive relationships of microbial communities
and the roles played by microbial populations within ecosystems.

Microhabitat: The individual faunal habitat or niche within a larger environment where environmental
conditions differ from those in a surrounding area, e.g. under logs, in rock crevices.

Mimetics: Compounds that mimic the function of other molecules via their high degree of structural
(conformational) similarity, and hence physio-chemical properties.

Mycorrhizae: fungi that grow underground on plant roots and have a mutual beneficial relationship with the

plant; in exchange for sugars and simple carbohydrates, the mycorrhizal fungi absorb and pass on minerals

and moisture required for the plant's growth

Native Species: Plants, animals, fungi, and micro-organisms that occur naturally in a given area or region.

Nitrification: Nitrification is a biological process involving the conversion of nitrogen-containing organic

compounds into nitrates and nitrites. It is part of the nitrogen cycle and considered to be beneficial since it

converts organic nitrogen compounds into nitrates that can be absorbed by green plants

Nitrogen fixation: The conversion of atmospheric nitrogen to biologically usable nitrates.

Non-linearity: A relationship or process in which a small change in the value of a driver (i.e., an independent
variable) produces an disproportionate change in the outcome (i.e., the dependent variable). Relationships
where there is a sudden discontinuity or change in rate are sometimes referred to as abrupt and often form
the basis of thresholds. In loose terms, they may lead to unexpected outcomes or “surprises.”

Non-timber forest products (NTFPs): all biological materials other than timber which are extracted from
forests for human use including edible plant and animal products, fibre, medicinal products

Pelagic zone: One of the two basic subdivisions of the marine system consists of the open sea and ocean and its
organisms, excluding the sea bottom (compare: Benthic zone)

pH: A measure of the acidity or alkalinity of a solution (power of Hydrogen); pH below 7 indicates an acid. pH
above 7 indicates a base.

Phenology: The scientific study of or the relationship of periodic biological phenomena, such as flowering,
breeding, and migration, in relation to climatic conditions.

Photosynthesis: The process by which chlorophyll-containing cells in green plants convert sunlight to chemical
energy (for growth and repair) and synthesize organic compounds from inorganic compounds,
accompanied by the release of oxygen

Phytoplankton: Microscopically small plants which float or swim weakly in fresh or salt water bodies

Pioneer species: A species that is an early occupant of newly created or disturbed areas. A member of the early
stage communities in ecological succession.

Primary producer: Organism that occupies the first trophic level in a food chain. They harness energy from
external environmental sources and convert it to stored energy that can be consumed by heterotrophic
organisms.

Protozoa: A large group of single-celled animals, such as amoebae, that are bigger and more complex than
bacteria and often cause disease.

Rattan: A vine-like palm native to Asia used for furniture, especially for caning and wicker because it is strong
and easy to manipulate.

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Resilience: The level of disturbance that an ecosystem can recover from without crossing a threshold to a
situation with different structure or outputs. Resilience depends on ecological dynamics as well as the
organizational and institutional capacity to understand, manage, and respond to these dynamics.

Resistance: The capacity of an ecosystem to withstand the impacts of drivers without displacement from its
present state.

Respiration: The process of oxygen uptake and carbon dioxide release while breathing. In plant physiology,
respiration refers to the cellular breakdown of sugar and other foods, accompanied by the release of energy

Rhizobia: Bacteria that form a symbiotic relationship with leguminous plants obtain and are responsible for
fixing atmospheric nitrogen into a form that can be used by plants and animals..

Riparian: Something related to, living on, or located at the banks of a watercourse, usually a river or stream.

SEA: Strategic Environmental Assessment (or Appraisal)

Secondary species: Plant species that arrive in a recently created or disturbed area, often replacing pioneer
species to form a shift in community composition.

Soil fertility: The potential of the soil to supply nutrient elements in the quantity, form, and proportion required
to support optimum plant growth.

Species diversity: Biodiversity at the species level, often combining aspects of species richness, their relative
abundance, and their dissimilarity.

Species richness: The number of species within a given sample, community, or area.

Symbiosis: Close and usually obligatory relationship between two organisms of different species, not necessarily
to their mutual benefit.

Synergy: When the combined effect of several forces operating is greater than the sum of the separate effects of
the forces.

Threshold: A point or level at which new properties emerge in an ecological, economic, or other system,
invalidating predictions based on mathematical relationships that apply at lower levels. For example,
species diversity of a landscape may decline steadily with increasing habitat degradation to a certain point,
then fall sharply after a critical threshold of degradation is reached. Human behavior, especially at group
levels, sometimes exhibits threshe!d effects. Thresholds at which irreversible changes occur are especially
of concern to decision-makers. (Compare Non-linearity.)

Transpiration: The process by which water is drawn through plants and returned to the air as water vapor.
Evapotranspiration is combined loss of water to the atmosphere via the processes of evaporation and
transpiration.

Trophic level: The average level of an organism within a food web, with plants having a trophic level of 1,
herbivores 2, first-order carnivores 3, and so on.

Turbid: Cloudy or opaque water due to the suspension of sediment

UNEP: United Nations Environment Programme

UNESCO: United Nations Educational Scientific and Cultural Organisation

Vector: An arthropod carrier of a disease producing organism.

WCMC: World Conservation Monitoring Centre (of UNEP)

WWFE: World Wide Fund for Nature

WTO: World Trade Organisation

Zoonotic disease: A disease of animals that may be secondarily transmitted to man

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