Succession and management - Ecological Applications: Toward a Sustainable World - page 215

appreciate that farmers battle with later-successional species when they maintain a pioneer-like
crop - some indigenous harvest practices are more straightforward
note that disturbance by fi re is an essential feature of many successions - but humans have
sometimes converted small, patchy fi re regimes into raging infernos
grasp that restoration of abandoned fi elds, clear-cut forests, degraded marshes and dunes requires
knowledge of the relevant successional processes
see that late-successional stages are often harder to invade than early stages, providing another
reason to restore mature communities
understand that many endangered animals and plants are characteristic of particular successional
stages - their conservation relies on successional theory

8.1 Introduction Jack loved the woodland cabin he built in Oklahoma. ' All the hassles of city life just

evaporated when I got back to the peace of my forest - you should have seen the spring
in my step and the smile on my face! ' But Jack's worry level began to rise after seeing
TV broadcasts from California of forest blazes that destroyed homes. He began a
campaign to persuade his State authorities to do something. ' I wrote to suggest that
the local stream should be dammed to provide a reservoir of water for fi re fi ghting. My
next idea was to cut down large strips of forest beyond the area with houses. ' Some of
his neighbors agreed, but others didn't - preferring to keep things natural because,
after all, that was why they chose to live there in the fi rst place. Jack's house was
one of those that burnt down late last summer.
In the natural world very little is constant. If conditions simply stayed the same,
ecological processes would be likely to move towards an equilibrium or steady state.
But disturbances to the status quo are common in every kind of habitat. Thus, in
many parts of the world fi res are natural occurrences, destroying much of what is
in their path, whether vegetation, animals or houses, but contributing to a natural
ecological mosaic of renewal and change. Hurricanes, fl oods and volcanic eruptions
are further examples of disturbances that affect ecological communities. My focus
in Chapters 2-4 was the application of knowledge about individual organisms. Then
I moved to the population level, exploring how population theory can be applied to
the management of endangered species, pest control and harvest management. Now
I shift to the community level of organization, and simultaneously consider all the
species that occur together in the shifting ecological mosaic.
Ecological communities have properties that are the sum of the properties of the
individuals they contain plus the interactions that take place among them (preda-
tor-prey, competitive, mutualistic, etc.). The interactions are what make the com-
munity more than the sum of its parts. Community ecologists are interested in how
groupings of species are distributed, and the ways these groupings can be infl uenced
by abiotic and biotic factors. One of the foundations of community ecology is the
concept of ecological succession - this is the relatively predictable sequence of change
in community composition observed after a disturbance. The theory of ecological
succession is summarized in Box 8.1. In this chapter you will learn that applied
ecologists cannot afford to ignore the reality of ecological succession. It is pointless
to plan our restoration schemes (Section 8.2), harvests (Section 8.3), biosecurity
policies (Section 8.4) or conservation projects (Section 8.5) on the assumption of
constant conditions when very often the reality is constant change.