Theoretical syntheses have highlighted a plethora of possible mechanisms that can drive energy flow through food webs and thus differences in the shape of biomass pyramids and the ratio of predator-to-prey biomass 6, 7. ![]() That is, biomass pyramids tend to be ‘bottom heavy’ in size-structured assemblages, where trophic level increases with body size 3, although this pattern is by no means universal 6. When partitioning individuals or species into trophic levels, the distribution of biomass along food chains tends to form a characteristic ‘pyramid’ pattern with greater standing stocks of biomass at lower trophic levels 1. The ratio of predator-to-prey biomass provides a key measure of trophic structure and community dynamics 1, 2, 3 and is linked to many ecosystem functions and services 4, 5. Understanding the processes that drive the structure and functioning of ecosystems is a fundamental goal in ecology. These general patterns in trophic structure are compatible with a systematic form of density dependence that holds among complex feeding interactions across levels of organization, irrespective of ecosystem type. Across food webs, a similar sub-linear scaling pattern emerges between total predator biomass and the combined biomass of all prey within a food web. more prey biomass supports proportionally less predator biomass. ![]() We find a consistent, sub-linear scaling pattern whereby predator biomass scales with the total biomass of their prey with a near ¾-power exponent within food webs - i.e. We test whether sub-linear scaling between predator and prey biomass (a potential signal of density-dependent processes) emerges within ecosystem types and across levels of biological organisation. ![]() Here, we address this shortcoming by characterising the biomass structure of 141 freshwater, marine and terrestrial food webs, spanning a broad gradient in community biomass. omnivory) that may govern community structure. The ratio of predator-to-prey biomass is a key element of trophic structure that is typically investigated from a food chain perspective, ignoring channels of energy transfer (e.g.
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