Effects of Hunting and Fragmentation Studied In an article “Synergistic Effects of Subsistence Hunting and Habitat
Fragmentation on Amazonian Forest Vertebrates” (Conservation Biology 15 (6):
1490-1505, 2001) Carlos A. Peres presents the following abstract.
Subsistence game hunting has profound negative effects on the species
diversity, standing biomass, and size structure of vertebrate assemblages in
Amazonian forests that otherwise remain largely undisturbed. These effects
are likely to be considerably aggravated by forest fragmentation because
fragments are more accessible to hunters, allow no (or very low rates of)
recolonization from nonharvest source populations, and may provide a
lower-quality resource base for the frugivore-granivore vertebrate fauna. I
examined the likelihood of midsized to large-bodied bird and mammal
populations persisting in Amazonian forest fragments of variable sizes
whenever they continue to be harvested by subsistence hunters in the
aftermath of isolation. I used data from a comprehensive compilation of
game-harvest studies throughout Neotropical forests to estimate the degree to
which different species and populations have been overharvested and then
calculated the range of minimum forest areas required to maintain a sustainable harvest. The size distribution of 5564 Amazonian forest
fragments–estimated from Landsat images of six regions of southern and
eastern Brazilian Amazonia–clearly shows that these are predominantly small
and rarely exceed 10 ha, suggesting that persistent overhunting is likely to
drive most midsized to large vertebrate populations to local extinction in
fragmented forest landscapes. Although experimental studies on this negative
synergism remain largely unavailable, the prospect that increasingly
fragmented Neotropical forest regions can retain their full assemblages of
avian and mammalian species is unlikely.
Posted 23 August 2002 |