Characteristics of Populations in Relation to Disturbance in Natural and Man-Modified Ecosystems

Abstract

Catastrophic, large-scale disturbances generate much of the observed community dynamics in nature (see reviews by Pickett and Thompson 1978; White 1979). Fire has been a major factor in the organization of plant communities and in the evolution of their species strategies. In the boreal forest of North America (Tande 1979) and other northern forests (Heinselman 1973) patches of differing species composition, age structure, etc. are created by fires. In the southern Wisconsin forest γ-diversity is generated and maintained by fires (Loucks 1970). Fire plays a similar role in the Mediterranean-type vegetation in the the Americas, Europe, Africa, and Australia (see reviews in Mooney et al. 1981). Much of the structure of the vegetation is determined by fire frequency and intensity in the Garrigue of southern France (Trabaud 1980). Wind throw, sometimes together with fire, seems to generate much of the pattern in the New England forest vegetation (Henry and Swan 1974; Oliver and Stephens 1977) and in the tropics (Gomez-Pompa 1971; Whitmore 1975). Other disturbance agents, e.g., landslides, earthquakes (Garwood et al. 1979), major climatic shifts, herbivores, predators, pathogens also play major roles in ecosystem structure and function.