Changing Species Richness and Composition in Canadian National Parks

Canada's national parks and their surrounding areas differ markedly in size, climate, vegetation, and extent of human development. We tested the extent to which total species richness, native species rich- ness, and the number of extirpations and introductions of terrestrial vertebrates were correlated with each of these factors. To do this, we used surveys of park fauna from the present andfrom the time of park establish- ment. Richness, extirpations, and introductions were all strongly related to climate. After we controlledfor cli- mate, smaller parks had higher rates of species loss than larger parks. Land-use patterns (forest cover and fragmentation, roads, etc.) wvithin parks were strongly correlated with land use in the regions surrounding the parks, showing that parks have not been isolated from regional development. Richness and extirpations within parks were generally more strongly related to regional characteristics than to the characteristics of the parks themselves. Species richness and numbers of introduced species were higher in parks found in land- scapes with greater fragmentation. Frequencies of extirpations were less clearly related to human-influenced habitat characteristics. Introductions and extinctions most often involved game species or species directly as- sociated with human activities. There is little evidence of subtle ecological effects being responsible for species loss. Our results suggest that management should focus on direct human interventions, such as hunting, in- troduction of game species, and habitat fragmentation, in parks and surrounding areas. Cambios en la Riqueza y Composici6n de Especies en Parques Nacionales Canadienses