Trait‐based approaches to unravelling the assembly of weed communities and their impact on agro‐ecosystem functioning

Abstract

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.

How to implement biodiversity-based agriculture to enhance ecosystem services: a review

“…For ecosystem services, depending on mobile-organism diversity, the effectiveness of local management strategies, for example at the farm level, will vary according to the complexity of surrounding landscape. Biological regulations will be low in cleared, i.e., extremely simplified, landscapes where most biodiversity has already been lost, but sometimes also in complex landscapes, where biodiversity and associated functioning such as pest biocontrol or crop pollination are already high (O'Rourk et al 2010;Tscharntke et al 2005). This assertion, expressed by Tschartnke et al (2012) in their "intermediate landscapecomplexity hypothesis," converges with the hypothesis of Biggs et al (2012) that argues that diversity-redundancy and connectivity are necessary to ensure provisioning and resilience of ecosystems services.…”

“…Traits can also be used to characterize organisms that are harmful for the crop and their relations with production situations and system performance, e.g., traits associated with foliar disease for wheat (Bingham et al 2009;Willocquet et al 2008). Similarly, trait-based approaches should give new highlights for predicting weed-community assemblages and impact on agroecosystem services, especially in complex communities for which a detailed mechanistic and modeling approach based on in-depth knowledge of all organisms involved would not be practical (Navas 2012). For example, soil food-web features can be indirectly assessed through plant functional types considered as proxies .…”

“…Such findings indicate powerful mechanisms available to farmers to favor beneficial insects by managing seminatural habitats at the farm level and, in contrast, less influential landscape features that farmers have less control over. Regarding the influence of landscape structure on trophic levels, several studies have demonstrated that predators and parasitoids appear to respond at smaller spatial scales than herbivorous insects (Brewer and Goodell 2012;O'Rourk et al 2010) and may be more susceptible to habitat fragmentation (Kruess and Tscharntke 2000). Complementarily, Thies et al (2003) argue for the general idea that higher trophic levels are more sensitive to landscape simplification, indicating a great need to analyze and understand the effect of landscape on biological regulations.…”

Functional traits in agriculture: agrobiodiversity and ecosystem services

“…Using traits to generate agroecosystem management strategies Previous efforts to integrate functional trait research into ecosystem service assessments have been proposed, but these have stopped short of creating tangible management targets that can be practically implemented by managers [20,39,65]. Farmers do not manage for traits directly, but rather manage agroecosystems by manipulating the abundances and location of species or through physical and chemical manipulation of the agroecosystem (e.g., tillage or fertilization).…”

“…For weed control, the functional traits of weed seeds and cover crop grasses at the plot level are key predictors of weed seed interception by grasses that prevent weed establishment [38]. Weed traits also have an important role in weed persistence and interaction with crop production [39], a reminder that functional traits can simultaneously contribute to agroecosystem services and disservices.…”