Effects of landscape pattern on competitive interactions

Abstract

Reviews several landscape-level mechanisms which may play a role in interspecific competition, using the following principle of coexistence as a guide: coexistence of two competing species is possible, under any mechanism and scenario of competition, if an individual's competitive action has a more harmful per capita effect on conspecifics than on heterospecifics. In landscapes consisting of similar habitat patches, coexistence is facilitated by a high migration/colonization rate in inferior competitors (the fugitive coexistence mechanism); by intraspecific spatial aggregation of the superior competitors (which increases the relative strength of intraspecific competition in relation to intraspecific competition); and by alternative local equilibria. All these mechanisms involve some ecological differences among the competitors. In landscapes with more and less productive habitat patches of qualitatively the same type, coexistence may be based on a negative correlation between species' performance in exploitation and interference competition, for instance due to body size differences. Landscapes consisting of different kinds of habitat patches typically facilitate coexistence due to differences in species' habitat selection. -from Author