. The economics of biodiversity loss: Scoping the science. than area while the fragment is small enough to have all of its area affected by edge effects (Figure 15b, green line). a) b> ?. 1 10 100 1000 10000 100000 forest fragment size (ha) forest fragment size (ha) Figure 15. a) Relationship between forest fragment size (note the logarithmic scale) and the diversity of mammal species (from Michalski and Peres 2007). b) Possible shape of the relationship between wild meat productivity (in biomass per year) and forest fragment size (see text for details). Michalski & Peres (2007) found a
. The economics of biodiversity loss: Scoping the science. than area while the fragment is small enough to have all of its area affected by edge effects (Figure 15b, green line). a) b> ?. 1 10 100 1000 10000 100000 forest fragment size (ha) forest fragment size (ha) Figure 15. a) Relationship between forest fragment size (note the logarithmic scale) and the diversity of mammal species (from Michalski and Peres 2007). b) Possible shape of the relationship between wild meat productivity (in biomass per year) and forest fragment size (see text for details). Michalski & Peres (2007) found a negative relationship between forest-patch area and two measures of the aggregate abundance of mammal species, and no variation for a third measure. However, overall abundance (number of individuals per unit area) is not an ideal measure of wild meat supply because it does not account for variation in body size across species. Indeed, if larger species are dominant in larger habitat patches, then a negative relationship is expected between area and abundance, even if standing biomass remains constant. Michalski & Peres (2007) found that larger species (, tapir, giant armadillo) only occurred in the largest fragments. On the other hand, larger-bodied species tend to reproduce slower, and so for the same standing biomass productivity may be higher for smaller fragments if they are dominated by small, fast-reproducing species (supporting hypothesis c, above). Michalski & Peres (2007) also found that for several species, there was a hyperabundance in small patches. They explained this as possibly resulting from: subsidies by matrix habitats ( presence of exotic fruit trees; supporting hypothesis e); the outcome of density compensation (increase in the abundance of one species as competition with other species declines; supporting hypothesis a); or the outcome of release from top predators (increase in abundance due to predator removal; supporting hypothesis e). In
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