Getting Quantitative about Consequences of Cross-Ecosystem Resource Subsidies on Recipient Consumers

Symposium Introduction: Most studies of cross-ecosystem resource subsidies have demonstrated a positive effect on consumer populations.  However, it is important to move past simple presence-absence studies to consider the quantitative impacts across gradients of resource input rates.  We will introduce some questions to focus on the potential future directions of this field and provide an introduction to the symposium.  Next, we used literature values from studies of leaf litter inputs and densities of consumers to generate simple models based on first approximations using temperature-specific assimilation efficiencies, resource input rates, litter quality and reach-scale retention of resources.  We compared these models against estimates from the literature. Across a wide spectrum of papers, these data indicate an asymptotic relation between inputs and production.  General models will be useful for predictions, but will also enable us to further consider what other factors are potentially limiting (e.g. nutrients, other population interactions, etc.) and better integrate resource subsidies into consumer-resource dynamics models.  Quantitative models can provide a tool to consider how subsidy inputs to one trophic level might influence the dynamics at the community level, since most published studies are of a duration too short to adequately determine responses at other trophic levels.