Consistent predator-prey biomass scaling in complex food webs.

Area of Science:

• Ecology
• Ecological modeling
• Food web dynamics

Background:

• Trophic structure, particularly predator-to-prey biomass ratios, is crucial for understanding community organization.
• Traditional food chain perspectives often overlook complex energy transfer pathways like omnivory.
• Existing research has not fully characterized biomass scaling patterns across diverse ecosystem types.

Purpose of the Study:

• To investigate biomass scaling relationships between predators and prey in various food webs.
• To determine if sub-linear scaling, indicative of density dependence, is consistent across ecosystem types and organizational levels.
• To characterize the biomass structure of 141 freshwater, marine, and terrestrial food webs.

Main Methods:

• Collected and analyzed biomass data from 141 diverse food webs (freshwater, marine, terrestrial).
• Quantified scaling relationships between predator and prey biomass using power-law exponents.
• Examined scaling patterns within individual food webs and across aggregated food web data.

Main Results:

• A consistent sub-linear scaling pattern was observed, with predator biomass scaling to prey biomass with a near ¾-power exponent within food webs.
• Across food webs, total predator biomass showed similar sub-linear scaling with the combined biomass of all prey.
• These scaling patterns were consistent across ecosystem types and levels of biological organization.

Conclusions:

• Sub-linear scaling in predator-prey biomass is a general feature of trophic structure in complex ecosystems.
• These findings support the hypothesis of systematic density-dependent processes operating across diverse feeding interactions.
• The observed patterns provide insights into the fundamental rules governing food web organization and stability.