Interim Report - TEEB

vation of tropical forest catchments might provide net
benefits to water compared to the same area as
grazing land or cropland, but these benefits might not
exceed the benefits of agroforestry on the same piece
of land (Chomitz and Kumari 1998, Konarska 2002).
Estimating extant biodiversity in these different
scenarios would add another layer of challenge. It
would be important to scope such scenario-based
assessment appropriately, to ensure that the main
purpose of our valuations (estimating the costs and
benefits of conservation of biodiversity) is not lost in
modelling alternative land uses.
• Non-linearity in the flow of services needs special
attention. For example, recent studies on coastal
mangroves in Thailand have taken into account that the
ecosystem service providing coastal protection does
not vary in line with the area of natural mangrove. This
leads to significantly different values and policy
conclusions compared to previous studies, notably
on the optimal mix between conservation and
development (Barbier et al. 2008). Another important
aspect is the existence of threshold effects and the
need to assess how close an ecosystem may be to the
collapse of certain services. There are still major gaps
in scientific knowledge about the role of species in
ecosystems and what the key factors are for producing
flows of beneficial ecosystem services and ensuring
their resilience. However, for some services, there is
evidence on the influence of certain biophysical
indicators (habitat areas, indicators of health, species
diversity, etc.). The Scoping the Science study
(Balmford et al. 2008) has reviewed the state of
ecological knowledge on a series of ecosystem
services and assessed the available information. The
findings of this study – which will be added to in Phase
II – will provide a basis for the economic evaluation by
means of:
o building appropriate scenarios for the provision of
each ecosystem service;
o defining for at least a set of services the method for
generating a global quantification and mapping of
service provision under different scenarios, upon
which to base the economic valuation;
o formulating reasonable assumptions to allow for the
extrapolation of values estimated for certain
ecosystems so as to fill data gaps.
• The links between ecosystem processes and the
benefits they provide to people vary in complexity and
directness. A classification system is needed, and can
be developed from the system built in the context of
the Millennium Ecosystem Assessment (2005b), which
can still be improved to provide a good basis for
economic valuation (following, for example, Boyd and
Banzhaf 2007, Wallace 2007, Fisher et al. in press). It
appears useful to distinguish between “final” services
(e.g. crop provision, clean water provision) that provide
benefits directly relevant for human welfare, and
“intermediate” services that serve as inputs for the
production of other services (e.g. pollination, water
regulation). The economic value of pollination, for
example, cannot be assessed separately from that of
the provision of crops. An end-user perspective must
be adopted: the value of intermediate services can only
be measured through their contribution to the
production of end-user benefits. We intend to structure
the classification of services for the evaluation in Phase
II around this perspective.
KEY PRINCIPLES OF BEST PRACTICE ON THE
VALUATION OF ECOSYSTEM SERVICES
These principles build on the recommendations made at the
Workshop on the Economics of the Global Loss of Biological
Diversity organized in the context of this project in Brussels
in March 2008 (ten Brink and Bräuer 2008).
1. The focus of valuation should be on marginal changes
rather than the “total” value of an ecosystem.
2. Valuation of ecosystem services must be contextspecific,
ecosystem-specific, and relevant to the initial
state of the ecosystem.
3. Good practices in “benefits transfer” need to be
adapted to biodiversity valuation, while more work is
needed on how to aggregate the values of marginal
changes.
4. Values should be guided by the perception of the
beneficiaries.
5. Participatory approaches and ways of embedding the
preferences of local communities may be used to help
make valuation more accepted.
6. Issues of irreversibility and resilience must be kept
in mind.
7. Substantiating bio-physical linkages helps the valuation
exercise and contributes to its credibility.
8. There are inevitable uncertainties in the valuation of
ecosystem services, so a sensitivity analysis should be
provided for decision makers.
9. Valuation has the potential to shed light on conflicting
goals and trade-offs but it should be presented in
combination with other qualitative and quantitative
information, and it might not be the last word.
In Phase II, we will exploit existing valuation literature in
greater depth and develop a methodology for choosing
Towards a valuation framework
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