Abstract
Identifying species with disproportionate effects on other species under press perturbations is essential, yet how species traits drive their keystone-ness and how this depends on community context remain unclear. We quantified species’ keystone-ness as the linearly approximated per capita net effect from normalized inverse community matrix and the nonlinear per capita community biomass change from simulated perturbations in food webs with varying biomass structure, the relationship between species’ body mass and their biomass within the web towards negative (bottom-heavy) or positive (top-heavy). We found top-heavy biomass structure weakened or even reversed the relationships between species’ energetic traits and keystone-ness observed in bottom-heavy webs. In bottom-heavy webs, larger species at higher trophic levels tend to be keystone species, whereas the opposite is true in top-heavy webs. Linear approximations aligned well with nonlinear responses in bottom-heavy webs but showed decreased consistency in top-heavy webs. These findings highlight the importance of community context in shaping species’ keystone-ness and informing effective conservation actions.
