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For J. Appl. Ecol.,  MS. J.A.E. 2004 / 177





A.H. Harcourt1 & D.A. Doherty2



1.    While in general the tropics and large-bodied tropical forest mammals are poorly known, the effects of fragmentation on tropical forest and the tropical mammalian order of primates are relatively well studied. Nevertheless, no quantitative synthesis exists of the response of primates to habitat fragmentation. We therefore conducted a meta-analysis of the literature on species-area relationships of primates in forest fragments in order to investigate continental regularities and differences among continents and sites.

2. The sample was 136 forest fragments (≤ 100 km2) at 33 sites in four continents (Africa, Asia, Madagascar, South America). We conducted our analysis at three spatial scales: global, by continent, and by site. As richness (number of species) per site varies, we present analyses of both richness and proportional richness by area.

3. Study sites and size of fragments are unequally distributed across the globe. South America has three times as many sites as does any other continent, for each of which we found less than ten sites. Fragment size is small in all continents (global median, 1.0 km2).

4. Despite considerable noise in the data, primate richness and proportional richness generally declined significantly and linearly with fragment area at all spatial scales - except in Africa.

5. Neither isolation (distance of fragment from main forest block), nor age of fragment, was an obvious influence on proportional richness. However, the global median isolation was only 2 km.

6. Synthesis and applications. Fragmentation of habitat clearly threatens the survival of primates.

However, study of the effects of fragmentation on primates might be directed in the wrong place. Estimates of minimum area requirements for primate species exceed tens of km2, yet most forest fragments studied measure less than one km2. Both to elucidate the biology of contrasts between species in susceptibility to fragmentation and in order to use research sites for associated conservation efforts, it might be better to direct more attention to fragments of a size in which long-term persistence of some species is possible.