Long-term dynamics of a fragmented rainforest mammal assemblage.
Habitat fragmentation is a severe threat to tropical biotas, but its long-term effects are poorly understood. We evaluated longer-term changes in the abundance of larger (>1 kg) mammals in fragmented and intact rainforest and in riparian "corridors" in tropical Queensland, with data from 190 spotlighting surveys conducted in 1986-1987 and 2006-2007. In 1986-1987 when most fragments were already 20-50 years old, mammal assemblages differed markedly between fragmented and intact forest. Most vulnerable were lemuroid ringtail possums (Hemibelideus lemuroides), followed by Lumholtz's tree-kangaroos (Dendrolagus lumholtzi) and Herbert River ringtail possums (Pseudocheirus herbertensis). Further changes were evident 20 years later. Mammal species richness fell significantly in fragments, and the abundances of 4 species, coppery brushtail possums (Trichosurus vulpecula johnstoni), green ringtail possums (Pseudochirops archeri), red-legged pademelons (Thylogale stigmatica), and tree-kangaroos, declined significantly. The most surprising finding was that the lemuroid ringtail, a strict rainforest specialist, apparently recolonized one fragment, despite a 99.98% decrease in abundance in fragments and corridors. A combination of factors, including long-term fragmentation effects, shifts in the surrounding matrix vegetation, and recurring cyclone disturbances, appear to underlie these dynamic changes in mammal assemblages.
Laurance
William F
WF
Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Panama. laurancew@si.edu
Laurance
Susan G
SG
Hilbert
David W
DW
D000704:Analysis of Variance; D000818:Animals; D055867:Cyclonic Storms; D017753:Ecosystem; D008322:Mammals / Q000502:physiology*; D011157:Population Dynamics; D011793:Queensland; D013045:Species Specificity; D014197:Trees; D014329:Tropical Climate