"Such negative synergisms could potentially be one of the most important -- and least understood -- aspects of the modern environmental crisis," say William Laurance of the Smithsonian Tropical Research Institute in Balboa, Panama, and Mark Cochrane of Michigan State University in East Lansing, who co-edited a five-paper special section called "Synergistic Effects in Fragmented Landscapes" in the December issue of Conservation Biology.
The findings in the special section include:
--hunting may accelerate extinction in fragments. A study of hunting in Amazon forest fragments found that the smaller the fragment, the greater the overharvesting of animals from peccaries to monkeys to curassows (turkey-, tree-dwelling birds). The disproportionate impact of hunting on fragments is presumably due partly to the fact that fragments are more accessible to hunters. This work is by Carlos Peres of the University of East Anglia in Norwich, the United Kingdom.
--fragments may also be more vulnerable to airborne pollutants. A study of atmospheric deposition in deciduous forest fragments in New York State found that during the growing season, sulfate is about 20% higher at the edge than in the interior. Moreover, nitrogen in the forest understory is about 45% higher at the edge than in the interior of fragments. Considered to limit the growth of many temperate trees, excess nitrogen could increase the growth of nitrogen-loving species along forest edges. This work is by Kathleen Weathers, Mary Cadenasso and Steward Pickett of the Institute of Ecosystem Studies in Millbrook, New York.