CORRIDORS MAINTAIN SPECIES RICHNESS IN THE FRAGMENTED LANDSCAPES OF AMICROECOSYSTEM

Theory predicts that species richness or single-species populations ca n be maintained, or at least extinctions minimized, by boosting rates of immigration. One possible way of achieving this is by establishing corridors of suitable habitat between reserves. Using moss patches as model microecosystems, we provide here probably the first field experi mental test of the idea that corridors can reduce the rate of loss of species, and therefore help to maintain species richness. Connecting p atches of habitat with corridors did indeed slow the rate of extinctio n of species, preserving species richness for longer periods of time t han in disconnected habitat patches. The pattern of gamma-diversity, t he cumulative species richness of entire connected systems, is similar ly higher than that of fragmented systems, despite the homogenizing ef fects of movement. Predators are predicted to be more susceptible to f ragmentation because of their greater mobility and smaller population sizes. Our data are consistent with this prediction: the proportion of predator species declined significantly in disconnected as compared w ith connected treatments.