Causes of the species-area relationship by trophic level in a field-based microecosystem.

Using a natural microecosystem, I test the contribution of the metapopulation effect to the species-area relationship, relative to that of the combined effects of habitat heterogeneity and sampling. The relative contributions were approximately equal, but with further relaxation of the fragmented community, the metapopulation effect is expected to increase. Predators had a greater slope to their species-area relationship than non-predators, and the habitat-plus-sampling effect was greater in predators than non-predators. This is the first attempt, to my knowledge, to quantify the causes of the species-area relationship.