This paper addresses the effects of the number of species that live in an ecosystem—its biodiversity—on ecosystem processes. This is a recent area of interest to the discipline, and one that has sparked controversy.

  Is it a condensation of previous literature on the subject?

The paper summarizes experimental work on this issue and interprets and extends theoretical work. I'd like to think that the paper provides a synthesis both of the mechanisms whereby biological diversity may impact how ecosystems function and of experimental tests of these ideas. The paper was initially presented in a forum (as the Robert MacArthur Award address to the Ecological Society of America) that encourages such syntheses.

Human actions are simplifying once complex ecosystems. For instance, prairie grasslands that once contained hundreds of plant species in a hectare have been converted to corn fields that contain essentially one grass species, maize, across hundreds of hectares. Habitat fragmentation and other human actions have reduced the number of plant and animal species living in remnants of native ecosystems. These changes raise a question of fundamental importance to the discipline and of interest to society: does the loss of diversity impact how ecosystems operate? This paper addresses this question by separating the potentially confounded effects of changes in diversity from those of changes in species composition. The paper explores these issues using models of competition among various numbers of species and using results of experiments in which species compositions were randomized at each of many different levels of plant diversity. In brief, the paper shows that diversity and composition are equally important determinants of ecosystem functioning, and suggests the theoretical foundations for these effects.

Read an in-depth interview with G. David Tilman from incites.