Environmental Engineering Reference
In-Depth Information
(Milner-Gulland & Mace, 1998), a theme that has gathered pace in the new millen-
nium. In 2002, for example, 190 countries committed themselves 'to achieve by 2010
a signifi cant reduction of the current rate of biodiversity loss at the global, regional
and national levels as a contribution to poverty alleviation and to the benefi t of all
life on Earth' (UNEP, 2002). The Millennium Ecosystem Assessment, launched in
2001, is also based on contributions from a large number of natural and social sci-
entists (Millennium Ecosystem Assessment, 2005b). Its aim is to provide both the
general public and decision makers with 'a scientifi c evaluation of the consequences
of current and projected changes in ecosystems for ecosystem services and human
well-being' (Balmford & Bond 2005). In the remaining sections of this chapter, I
introduce the ecological (Section 1.3.1), economic (1.3.2) and sociopolitical (1.3.3)
dimensions of sustainability.
1.3.1
Ecological
applications - to
conserve, restore and
sustain biodiversity
The body of ecological theory is organized in a hierarchical way. My focus in this
topic will be on ecological applications, but these will be presented in a sequence
that mirrors the underlying theory.
At the lowest level is the ecology of
individual organisms
- their niche requirements
(resource needs and tolerance of physicochemical conditions - Chapter 2), their
life-history characteristics (Chapter 3) and their dispersal/migratory behavior
(Ch apter 4). K nowledge at this level is crucial when reintroducing species that have
become locally extinct, restoring natural grassland and forest, or predicting invaders
likely to pose a major problem. See Box 1.2 for ecological tidbits from each
chapter.
Next comes the
population
level of ecological organization. The population com-
prises all the individuals of a single species in a particular place, and the focus is
on factors that determine the density and genetic diversity of populations. Popula-
tion theory is central to the management of endangered species (Chapter 5), pests
(Ch apter 6) and harvests (Ch apter 7).
Moving up another step in the ecological layer cake,
community
ecology concerns
itself with all the species that coexist. Two areas of community ecology of particular
importance for environmental management are succession (the predictable temporal
pattern in species composition after a disturbance such as a storm or fi re - Chapter
8) and patterns in the feeding interactions of food webs. When the spotlight is
turned on the community in relation to its physicochemical environment, and spe-
cifi cally the fl ux of energy and matter through the food web, we talk of the
ecosystem
level of organization (Chapter 9). Ecological theory associated with communities
and ecosystems helps managers devise plans to conserve and restore natural com-
munities, counteract invasions, increase the range of harvestable products and make
agroecosystems sustainable. And of course, ecosystem theory underpins the whole
idea of ecosystem services and their contribution to human well-being.
The last part of the topic combines examples from all levels in the ecological
hierarchy but shifts emphasis to a larger spatial scale, dealing with landscape
ecology (the patchwork of habitats in the landscape as a whole - Chapter 10) and
fi nally with the global environment, where global climate change becomes the focus
(Ch apter 11). L a nd sc ape ecology is crucial when designing networks of nature
reserves, but often also when planning conservation, restoration, harvests and pest
control. And global climate change has implications for everything else - whether
at the level of individuals, populations, communities, ecosystems or landscape
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