Environmental Engineering Reference
In-Depth Information
ecological theories (Freyfogle & Lutz Newton
2001
). Consequently, at an
operational level, it is a societal decision whether the aspiration to 'naturalness'
has primacy to other values and demands that humans place on ecosystems.
Sustainable ecosystems and sustainable societies?
Humans place both direct and indirect demands on ecosystems, whether for
basic provisioning (food, water and fuel), or the regulating and renewing
processes that maintain suitable environmental conditions for life. The con-
ditions and processes through which ecosystems sustain human life have
been termed ecosystem services (Constanza et al.
1997
) and have been classi-
fied as provisioning services (ecosystem goods, such as food and timber),
regulating services (e.g., regulation of climate, floods and water quality),
cultural services (e.g., recreation, aesthetic enjoyment and spiritual fulfill-
ment) and supporting services (e.g., soil formation, nutrient cycling and
photosynthesis), which are necessary for the production of all other services
(Millennium Ecosystem Assessment
2005
). In addition to ecosystem services
influencing human well-being, human well-being influences ecosystem ser-
vices through direct and indirect drivers of change (
Fig. 16.4
). Economic
development, often associated with industrialisation, is generally associated
with improved standards of living, reduced infant mortality and increased
life expectancy. However, economic development requires energy, generates
waste and often results in social inequalities. Energy demands are supplied by
extracting fossil fuels or harvesting timber, and waste material is released
into waterways, disposed of in landfill or burnt; all of which have environ-
mental impacts (Hodgson et al.
2007
).
Ecosystem services are likely to be interdependent and the management or
optimisation of one service may have negative consequences on others (Rogri-
guez et al. 2006). As human influence on the world's ecosystems increases,
understanding and managing potential trade-offs resulting from the various
demands society places on ecosystems becomes ever more important. Because
existing ecological quality definitions do not really allow us to address these
issues, we are challenged to develop alternative ways of defining ecological
quality that can accommodate the different demands that society places on
ecosystems, account for potential trade-offs between them and be applied at
the scales at which management operate. Deriving such definitions will allow
us to explore the robustness and generality of those definitions in principle,
and then the challenges in making them operational. Here we suggest one such
definition, explore some of the attributes such a measure might have and
consider some of the practicalities of its implementation. As illustration of the
ideas involved, we draw on some of the issues of quality and service provision
that arise in the context of river, or catchment, management.
