Salzau 2010
Abstracts
February 2010
Linking ecosystem services and biodiversity
J.H. Spangenberg & J. Settele
Ecosystem services ESS are outputs of ecosystems (goods or services) recognised
as such and valued by humans. As flows, they can be measured. ESS can be
essential or not, ubiquitous or localised, abundant or scarce. In the latter case, and if
by their character or through social or legal provisions exclusive use is possible, the
value humans attribute to the respective service can be monetised. ESS are social
constructs, and so is their value.
Some scholars define ecosystem functions as service delivery potentials and try to
value and monetise them just alike the services themselves. However, to be able to
do so they cannot calculate the value of the total service provision potential (it is
mostly unknown), but (implicitly) introduce a load factor, valuing the realised potential
(which is the actual service provision). In this paper we refrain from using this kind of
service-driven definition. We understand ecosystem functions to be biogeochemical
characteristics of ecosystems and their (i) development dynamics and (ii) emergent
properties on different system levels, relevant for the ecosystem, its functioning and
development itself, regardless of any human valuation. Ecosystem functions in this
sense are not social constructs but system characteristics; the human influence lies
in the ways we perceive and describe them. They are functions of the system, not
functions for something.
Biodiversity is a natural phenomenon. The term summarises the diversity (in
composition of elements and their spatial and temporal arrangement) of system
elements, the systems being gene pools, organisms, populations, species or
ecosystems. As a rule of thumb, in any observation (i.e. a point in time and space)
the number of system elements of the same class (e.g. organisms of the same
species) decreases with higher biodiversity, while there is an increase in the number
of observable classes.
The individual system elements (organisms, species) can be “objects of desire” in
themselves, i.e. be directly used (hunting, gathering, including modern “gene
hunting”): then their occurrence can be considered a direct ecosystem service of the
bio-geological entities. Simultaneously they can contribute to ecosystem functions
which may as well be valuable to humans (in this case a conflict of interest between
direct use and preserving the indirect use potential, the ESS, can emerge).
The diversity of system elements influences the service provision: The higher the
diversity, the lower (in average) the density of any specific class; and that implies
more efforts in reaping any specific fruit of the respective ecosystem. In other words:
Salzau 2010
Abstracts
February 2010
for every specific service (e.g. rabbit hunting, maize harvesting) diversity tends to
decline the yield, but not necessarily so for broader defined services. Hunting
vertebrates or harvesting grain may be more successful as more elements in those
classes can be expected to prevail. In these cases the link between biodiversity and
ESS is dominated by the anthropogenic definition of the respective ESS. This
description applies mainly to relatively simple (sub-) systems and to provisioning and
cultural services.
From an ESS perspective organisms can be classified in three categories:
(1) The accessibility of the organism itself is providing the service (honey, meat,
medicine, etc.)
(2) The organism co-produces a recognised service, together with other
ecosystem elements, and is recognised as doing so (e.g. insects &
pollination). This includes minimising disservices from other organisms
(regulation through bio-control).
(3) The organisms provides no known contribution to recognised ESS. This may
be because
i.
the beneficial role of a certain ecosystem function which is (co)generated by the organism has not been recognised as beneficial, i.e.
as a service so far (often for supporting services),
ii.
the service – i.e. the usefulness of a function – has been recognised,
but not the role of the organism in providing it (occurring e.g. for
regulating services),
iii.
the organism does not contribute to ecosystem services (some scholars
think this is the case for the majority of species, while others assume
that they are more or less all involved in supporting services, making
these a kind of residual category).
Research needs
In case (1) the open questions concern measurement and valuation. Better
understanding cases (2) and (3ii) is a core issue of ecosystem research, including
socio-economic (including cultural) valuation and – where appropriate - monetisation.
Case (3) is the one causing problems. (3i) refers to a moving target, since the
recognition is a complex social process, and what is rightfully acknowledged as a
service depends on the respective culture, technology and population group. All
these factors are dynamic, and so is the selection of functions to be acknowledged
as services. Social science as well as ecosystem research contribute to fill gaps of
current knowledge and acknowledgement, but can hardly influence future service
definitions. This is a strong argument for conservation, as what is deemed negligible
today may be essential for tomorrow’s service definitions.
Salzau 2010
Abstracts
February 2010
Case (3iii) is the biggest challenge, as it refers to a situation of ignorance: neither are
all functions known (or will ever be – it is also a matter of definition), nor will it be
possible to identify all contributors to any given function, across all system levels.
Here the precautionary principle applies for biodiversity management even in the
absence of any known relation to ESS.
The paper discusses these challenges with special emphasis on the energy flow and
HANPP background of biodiversity, and points out need for a precautionary approach
given the uncertainties inherent to biodiversity measurement.