HABITAT DESTRUCTION AND THE EXTINCTION DEBT

HABITAT destruction is the major cause of species extinctions(1-3) Dom inant species often are considered to be free of this threat because t hey are abundant in the undisturbed fragments that remain after destru ction. Here we describe a model that explains multispecies coexistence in patchy habitats(4) and which predicts that their abundance may be fleeting. Even moderate habitat destruction is predicted to cause time -delayed but deterministic extinction of the dominant competitor in re mnant patches. Further species are predicted to become extinct, in ord er from the best to the poorest competitors, as habitat destruction in creases. Moreover, the more fragmented a habitat already is, the great er is the number of extinctions caused by added destruction. Because s uch extinctions occur generations after fragmentation, they represent a debt-a future ecological cost of current habitat destruction.