ABSTRACT
So far statements in the text have been mainly illustrated with examples from the plant world. In this chapter the emphasis is largely on examples from animal ecology. The intricate nature of biotic communities was stressed in previous chapters. Plant succession, usually leading to an increase in plant diversity, is broadly paralleled by animal succession. The complex mature ecosystems that evolve are characterized by control mechanisms. These help to stabilize the natural community and numbers of any one species tend to remain reasonably constant over long periods. Nevertheless, some species do show fairly regular, dramatic population fluctuations, e.g. Arctic lemmings. However, recent research, such as the work of Krebs, shows that these fluc tuations are probably just as common in tropical and temperate ecosystems.
