Environmental Management: Principles and practice

The ecosystem concept
The ecosystem concept may be applied to natural or human-modified conditions.
The latter include urban ecosystems and agroecosystems, although these are not
true, discrete units in terms of energy flows, function and so on. Ecosystem
FIGURE 7.3 A glacier calving into the sea, Cumberland Bay, South Georgia. Evidence shows
considerable change in extent of glaciers on this island over the last 10,000 years. Climate is
not static.

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management is the application of the ecosystem concept (Golley, 1993). Slocombe
(1993) was optimistic that the ecosystem concept might offer a route to integrating
environmental management and development planning that would lead to sustainable
development (the value of the ecosystem approach is discussed in chapter 9).
Biodiversity
Ecological diversity refers to the range of biological communities that interact with
each other in a given environment. Biodiversity (biological diversity) refers to species
diversity plus genetic diversity within those species. Loss of biological diversity
occurs when species extinctions exceed the rate of species creation. Extinction is a
natural process, sometimes sudden, perhaps catastrophic, otherwise an ongoing,
gradual process. However, humans have greatly accelerated the rate of extinctions.
Loss of biodiversity is one of the most serious problems facing environmental
managers.
Biogeochemical and biogeophysical cycles
Within the biosphere, cyclic processes move and renew supplies of energy, water,
chemical elements and air. These cycles affect the physical environment and
organisms, and some are affected by life forms. Although upset by occasional
catastrophic events (e.g. volcanic eruptions, planetesimal strikes), biogeochemical
and biogeophysical cycles are assumed to reach a state of dynamic stability.
Nevertheless, environmental managers must not assume an unchanging natural
environment, and human activity is affecting global cycles and might trigger serious
runaway problems (i.e which are difficult to solve).
There are cycles which are crucial for the nutrition of organisms: the
maintenance of atmospheric gas mix and maintaining global temperature within
acceptable limits, including water, oxygen, carbon dioxide, nitrogen, phosphorus,
sulphur (there are over 30 known biogeochemical cycles). Some involve gases and
have a turnover of as little as a few days; some involve sediments, and are so slow
(with turnovers of perhaps millions of years) that the material is non-renewable as
far as humans are concerned. Biogeochemical and biogeophysical cycles are not
fully understood, for example, there is much to learn about the cycling of carbon.
Without better insight, accurate modelling and prediction of global change is very
difficult.
Biogeochemical and biogeophysical cycles can be classified as: (1) natural,
(2) upset by humans and (3) recycling (managed by man and sustainable) (Chadwick
and Goodman, 1975:4). Many of the first group have already been converted to the
second and the threat of this grows; conversion of these to the third group is an
important goal for environmental managers.

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