Body Mass-Biomass Scaling Modulates Species Keystone-Ness to Press Perturbations

Area of Science:

• Ecology
• Food web dynamics
• Conservation biology

Background:

• Identifying keystone species, which have disproportionate effects on ecosystems, is vital for conservation.
• However, how species traits and community context influence keystone-ness remains poorly understood.

Purpose of the Study:

• To quantify species' keystone-ness using linear approximations and non-linear community biomass changes.
• To investigate the influence of food web biomass structure on the relationship between species traits and keystone-ness.

Main Methods:

• Quantified keystone-ness via normalized inverse community matrices (linear approximation).
• Simulated perturbations in food webs with varying biomass structures to assess non-linear per capita community biomass change.
• Compared keystone-ness in bottom-heavy and top-heavy food webs.

Main Results:

• In bottom-heavy webs, larger, higher-trophic-level species were often keystone species.
• In top-heavy webs, keystone-ness patterns reversed, and trait-keystone relationships weakened.
• Linear approximations of keystone-ness matched non-linear results in bottom-heavy webs but not in top-heavy webs.

Conclusions:

• Community context, particularly biomass structure, significantly shapes species' keystone-ness.
• Findings emphasize the need to consider food web structure for effective conservation planning and species identification.