EFFECTS OF RESOLUTION ON FOOD WEB STRUCTURE

This analysis of 11 large community food webs shows that food web structure systematically varies as the trophic resolution of food web data is reduced. Mean chain length, the ratio of links per species, and the fractions of intermediate species and links between intermediate species decrease as the trophic-species webs are aggregated to half their size. Concurrently, the fractions of top species, basal species, and links between top and basal species increase. Directed connectance and the predator/prey ratio appear to be relatively robust to reducing the trophic resolution of food web data. Significant effects of reducing the taxonomic resolution of food webs are also demonstrated. These findings are inconsistent with prominent claims that most properties are robust to varying the resolution of food web data. Problems responsible for this inconsistency are identified.