SIMPLIFYING THE COMPLEX - THE PARADIGMS OF ECOLOGICAL FUNCTION AND STRUCTURE

Ecosystem change has usefully been seen as controlled by two functions: exploitation, where rapid colonization of recently disturbed land is emphasized, and conservation where slow accumulation and storage of energy and material are emphasized. Analysis of a series of ecosystems-managed and unmanaged-indicates there are two additional functions. One is that of creative destruction where the tightly bound accumulation of biomass and nutrients is suddenly released by agents such as forest fires, insect pests, or intense grazing. The second function is one of renewal where released material is mobilized to become available for the next exploitive phase. That pattern is discontinuous and is dependent on the existence of multistable states. Resilience and recovery are emphasized during the release and renewal sequence, and stability and productivity during the exploitation and conservation sequence. Such studies of resilience are beginning to combine with hierarchy theory and with the theory of dissipative structures to deepen our understanding of change and how to manage change.