Determining the effects of warming on consumer-resource communities represents a persistent and timely challenge. Previous empirical and theoretical studies have reported various and sometimes contradicting impacts of warming on community stability and biomass distribution across trophic levels. A major obstacle to obtaining accurate predictions stems from the lack of consensus on how temperature influences key physiological, behavioural and production rates that underpin consumer-resource models and determine the community response to warming. Here, we systematically investigated how temperature changes impact community standing biomass and stability by performing a sensitivity analysis of all parameters. We used the established Rosenzweig-MacArthur model, selecting consumer-resource biomass ratio and the tendency for oscillations as two community variables of interest. We derived two aggregate parameters - consumer energetic efficiency (ρ) and interaction strength (κ) – that help describe the biomass distribution and drive the stability of the consumer-resource system. We then implemented different temperature parameterisations from the literature and studied the links between predictions, the temperature-dependencies and underlying stability assumptions.
Results/Conclusions
All sensitivities were explicitly represented in terms of ρ and κ, with distinct regions of the ρ-κ plane corresponding to different parameter sensitivity rankings. By mapping empirically determined temperature dependencies of individual parameters onto the ρ-κ plane, we observed the impact of temperature on the consumer-resource community. Specifically, biomass ratio was always most sensitive to consumer efficiency and metabolism, with resource growth rate being equally important away from consumer extinction (majority of temperatures). Stability was most sensitive to consumer efficiency and metabolism close to consumer extinction (temperature extremes) and to the functional response and productivity away from it. One implication for empirical studies is to mainly focus on these three parameters when investigating standing biomass responses to warming as the other parameters (attack rate, handling time and carrying capacity) have a weak influence on biomass ratio. Another implication regards the reduction in the complexity of parameterising consumer-resource community dynamics from a six- to a two-dimensional problem. This also limits the complexity for future studies investigating the impact of warming on the stability of consumer-resource communities; as our results indicate this can be achieved by determining the thermal dependence of consumer intrinsic growth rate and interaction strength.