Publication

Concerted effort in ecology is focused on developing synthetic frameworks that quantify general trends between diversity of organismal functional traits and ecosystem functioning. Yet much variation about the general trend routinely remains unexplained by trait diversity alone. We argue that this arises because these approaches fail to consider flexibility in trait expression as organisms adaptively respond to different environmental contexts (e.g., changes in resource quality or consumer pressure). We present here a framework for resolving how flexibility in functional trait expression is related to ecosystem functioning. We propose an approach that considers focal species, their resources and their consumers as a modular trophic unit. The approach then examines functional trait expressions of focal species when juxtaposed between different resource species (and associated traits) and consumer species (and associated traits). In such cases, focal species not only directly respond to different resource qualities and consumer pressure, but also mediate the indirect effects of consumer pressure on resource quality, causing feedbacks that ramify through ecosystems. Using case studies, we illustrate the utility of our modular approach for understanding how functional traits determine ecosystem functioning in a variety of aboveground and belowground trophic modules within ecosystems. We offer some general principles for explaining how variation in interactions among species determines variation in ecosystem functioning through a lens of flexible functional traits expression.