Ecosystem Responses to Community Disassembly

Ecosystems around the world are experiencing unprecedented rates of extinction and species decline. The question of how community disassembly-the ongoing process of nonrandom species losses and declines-affects ecosystem functions, including those that influence persistence of other species, is addressed. The order in which species disappear from a community depends on their vulnerability to specific stressors and on traits associated with inherent susceptibility to decline. Information on species characteristics associated with vulnerability (response traits) is synthesized, and it is asked whether they are associated with characteristics that underpin significant contributions to ecosystem functioning (effect traits). Direct evidence that community disassembly affects ecosystem functioning comes from a variety of sources, ranging from documentation of long-term changes following the loss of an initial species or fragmentation of a landscape, to modeling and manipulative experiments that simulate species losses and observe their consequences. The usefulness to conservation and restoration practice of community disassembly as a concept is evaluated, and it is asked whether and how community disassembly can provide guidance about species loss order, its consequences, what each of these depends on, and whether a positive link exists between vulnerability and contribution to function-a link that would exacerbate the consequences of the ongoing extinction crisis.