Scale invariance in food web properties.
The robustness of five common food web properties is examined by varying the resolution of the data through aggregation of trophic groupings. A surprising constancy in each of these properties is revealed as webs are collapsed down to approximately half their original size. This analysis of 60 invertebrate-dominated community food webs confirms the existence of all but one of these properties in such webs and addresses a common concern held by critics of food web theory that observed food web properties may be sensitive to trophic aggregation. The food web statistics (chain length; predator/prey ratio; fraction of top, intermediate, and bottom species; and rigid circuits) are scaling in the sense that they remain roughly invariant over a wide range of data resolution. As such, within present standards of reporting food web data, these statistics may be used to compare systems whose trophic data are resolved differently within a factor of 2.
Sugihara
G
G
Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093.
Schoenly
K
K
Trombla
A
A
D000818:Animals; D005502:Food; D005523:Food Supply; D007448:Invertebrates; D008954:Models, Biological