Predicting ecosystem responses to global change is a major challenge in ecology. A critical step in that challenge is to understand how changing environmental conditions influence processes across levels of ecological organization. While direct scaling from individual to ecosystem dynamics can lead to robust and mechanistic predictions, new approaches are needed to appropriately translate questions through the community level. Species invasion, loss, and turnover all necessitate this scaling through community processes, but predicting how such changes may influence ecosystem function is notoriously difficult. We suggest that community-level dynamics can be incorporated into scaling predictions using a trait-based response-effect framework that differentiates the community response to environmental change (predicted by response traits) and the effect of that change on ecosystem processes (predicted by effect traits). We develop a response-and-effect functional framework, concentrating on how the relationships among species' response, effect, and abundance can lead to general predictions concerning the magnitude and direction of the influence of environmental change on function. We then detail several key research directions needed to better scale the effects of environmental change through the community level. These include (1) effect and response trait characterization, (2) linkages between response-and-effect traits, (3) the importance of species interactions on trait expression, and (4) incorporation of feedbacks across multiple temporal scales. Increasing rates of extinction and invasion that are modifying communities worldwide make such a research agenda imperative.

Navas M‐L (2012). Trait‐based approaches to unravelling the assembly of weed communities and their impact on agro‐ecosystem functioning. Weed Research52, 479–488. Summary The trait‐based approach to plant functional ecology has gained considerable attention over the last two decades, allowing ecologists to address questions relating to species distribution, community assembly and ecosystem functioning. We show here how this approach can be used to address these issues for weed ecology in a new way, allowing research to shift from purely weed control issues to a more global understanding of the impact of weed communities on the agro‐ecosystem. We review how weed species are sorted by environmental factors and management according to the value of traits and the role thereof in the assembly of weed communities. How weed trait values and their distribution within communities affect agro‐ecosystem processes is discussed in relation to loss of crop production. We also introduce the question of the impact of weed functional structure on ecosystem services and suggest some directions for research at species, community and agro‐ecosystem levels.

Summary: The aim of this paper is to show the need for developing plant population biology studies in order to improve weed management when traditional approaches in weed science have failed, as shown by recent reviews on herbicide resistance. It is also suggested that the usual weed definitions do not reflect the new aims of weed ecology. The results of studies on the genetic, demographic and spatial variability of weed populations and their regulation by pests and pathogens are reported, and are discussed in the specific case of clonal perennial species.

No abstract

No abstract