1. Division of Ecosystem Management, University of New England, Armidale, New South Wales, 2351 Australia,
2. Institute of Ecosystem Studies, Millbrook, New York 12545;
3. University of Savoie, G.R.E.T.I., ESA-CNRS #5023, Le Bourget du Lac, 73376 France;
4. Department of Zoology, Oklahoma State University, Stillwater, Oklahoma 74078-3052;
5. Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061