We thank D. A. Crossley Jr., S. J. McNaughton, E. P. Odum, L. L. Wallace, and three anonymous reviewers for valuable discussions that have helped us present our arguments. NASA Grants NAG 5-897 and NAG-5-910 along with NSF long-term ecological research Grant BSR-8514327 to Kansas State University and BSR-8904632 to M. I. Dyer helped obtain the database from which we have derived our analyses for this study.
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