Species Richness and Resistance to Invasions

摘要: Traditionally, tropical forests, and especially rain have been contrasted with extratropical communities in terms of their species diversity stability (Elton 1958). Unfortunately, ecologists used the word’ stability’ to mean several different things (Orians 1975; Harrison 1979; Pimm 1984): Resilience can be defined as a rate return population densities, community composition, or collective properties like biomass production, conditions preceding perturbation. Persistence usually means how long presence individual populations composition last. Resistance degree which variable interest remains unaltered following Constancy lack change (low variability) variables over time. Finally, systems are stable narrow sense if, only initial (equilibrium) values, Elton (1958) himself switched between meanings when he talked about absence insect outbreaks forests (high constancy) higher frequency extinctions invasions simple persistence). suggested that rich possess “complex checks buffers” responsible for stability. Causal positive connections biotic low variability high persistence comunities questioned many times since Elton’s influential book was published (Futuyma 1973; Farnworth Golley 1974; Leigh Wolda 1978, 1983; Maury-Lechon et al. 1984). Elton, however, should prized drawing long-lasting attention relationships ecological systems.