RELATIVE EFFECTS OF HABITAT LOSS AND FRAGMENTATION ON POPULATION EXTINCTION

In their review of the recent ''explosion of spatially explicit theory '' in ecology Kareiva and Wennergren (1995) suggest a number of emergi ng principles for species conservation. One of these principles is tha t how habitats are arranged in space can mitigate the risks of species extinctions from habitat loss. I tested this by estimating the relati ve importance of habitat loss and habitat spatial pattern (fragmentati on) on population extinction, using a simple, spatially explicit simul ation model. Results indicate that the effects of habitat loss far out weigh the effects of habitat fragmentation. I therefore suggest that, in fact, details of how habitats are arranged cannot usually mitigate the risks of habitat loss. Conservation efforts should be aimed foremo st at stopping habitat loss and at habitat restoration.