Arctic-Alpine Plants on Mountaintops: Agreement with Island Biogeography Theory

The number of arctic-alpine plant species on 13 alpine summits in the Adirondack Mountains is related to the area of the alpine ecosystems and to immigration indices based on the distances between summits. Seventy-one percent of the variance in the number of species in individual communities is explained by a regression of species number on the natural logarithm of ecosystem area, and 59% of the remaining variance is explained by an immigration model which assumes that plant propagules are carried between mountains by birds or other animals. The results suggest that immigration is an ongoing process in the alpine communities and that the alpine plants are not merely relict populations.