Environmental Management: Principles and practice

Applying the ecosystem concept to urban and peri-urban
management
More than half the world population now live in conurbations and the effects of
urban settlement, in the form of fuelwood demand, air pollution and contamination
of watercourses, are increasing and are felt at growing distances into the surrounding
regions (White, 1994). As with tourism, there is a growing literature on urban
environmental management. An ecosystem approach can help to identify strategies
that can reduce pollution, aid safe disposal of pollutants and production of food,
together with some provision of employment—through activities like urban
agriculture. At a regional or national scale it may be possible to understand the linkages
that have driven people to settle urban areas, often abandoning once sustainable
rural livelihoods (Dorney and McLellan, 1984).
Applying the ecosystem concept to conservation management
Forest management and wildlife conservation make extensive use of the ecosystem
approach (Lajeunesse et al., 1995; Bailey, 1996; Samson and Knopf, 1996; Boyce,
1997; Weeks, 1997). Biosphere reserves are essentially islands in a sea of disturbance
(whether terrestrial ecosystems or aquatic, such as coral reefs), so the study of island
ecosystems by biogeographers like David Simberloff, Edward Wilson and Robert
McArthur (McArthur and Wilson, 1967; di Castri and Robertson, 1982) provides
key information on rates of extinction and evolution; minimum size of habitat and
linkages between habitats necessary for sustained conservation; whether to conserve
selected species or a whole ecosystem; assessment of likely impacts of climate change
or acid deposition; clarification of vital pollination and seed dispersal needs;
information on predator-prey relationships, and so on (Miller, 1978; Goeden, 1979;
Higgs, 1981; Mueller-Dombois et al., 1981). Caution is needed, for some of the
island biogeographic theory which conservation managers draw upon is incomplete,
imprecise, or has been little tested (Shrader-Frechette and McCoy, 1994).
Once established, a conservation area may fail to sustain biodiversity because
it is too small for species to breed and feed, or because disruptive edge effects penetrate
too far (Soule, 1987). Studies have been in progress for some years in the Amazonian
forests of northern Brazil to improve understanding of the impact of various intensities
of forest disturbance and ecosystem fragmentation on biodiversity survival using

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different sizes and patterns of forest fragments (for an introduction to island
biogeography, and a discussion of the Minimum Critical Size of Ecosystem Study
undertaken in Amazonia see Quammen, 1997). These studies, and similar ones
elsewhere, are vital for establishing what are viable locations, ideal size and pattern
of conservation areas (whether several smaller reserves offer greater security and
hold more or fewer species than one larger, and whether multiple reserves should be
linked by corridors to facilitate movement of flora and fauna).