Functional biogeography of weeds reveals how anthropogenic management blurs trait–climate relationships

Abstract

Questions: Studies in functional biogeography have mostly focused on unmanaged ecosystems, and neglected testing how management intensity affects communitylevel response of plant traits to bioclimatic gradients. We hypothesize that traitclimate relationships for arable weeds spontaneously establishing in croplands subject to intensive management should differ from the relationships characterizing less intensively managed grassland ecosystems. Location: France.Methods: We computed community-weighted means (CWM) and variances (CWV) of 954 and 5,619 cropland and grassland plant assemblages, respectively, for three fundamental leaf traits (specific leaf area, SLA; leaf dry matter content, LDMC; leaf nitrogen content, LNC). Based on growing season length accounting for both temperature and soil water limitations (GSL tw ), we compared trait-climate relationships between herbicide-free croplands and grasslands, and between herbicide-free and herbicidesprayed cropland assemblages. The contribution of beta-diversity to the trait-climate relationships was then evaluated using multiple regression on distance matrices.Results: Distinct trait-climate relationships characterized herbicide-free cropland and grassland plant assemblages. CWM of all traits showed weaker relations with GSL tw in cropland relative to grassland assemblages. CWV of LDMC and LNC responded more sharply in croplands. Furthermore, no herbicide effect on trait-climate relationships was detected within cropland assemblages. These results seem to be explained by a greater taxonomic beta-diversity along the GSL tw gradient for grasslands.Conclusions: Specific trait-environment relationships characterize croplands, underlining that management intensity greatly affects trait-climate relationships for plant assemblages. Deciphering the interplay between land use intensification and climate is critical to accurately forecast functional vegetation changes in response to global changes, and hence to foster actions enhancing ecosystem resilience.

Landscape Is the Main Driver of Weed Assemblages in Field Margins but Is Outperformed by Crop Competition in Field Cores

“…This suggests that in absence of strong filtering factors such as competition or disturbances, climate has a higher filtering effect on weed assemblages. Indeed, a recent study investigating traitclimate relationships in plant assemblages revealed that these relationships were much weaker in croplands compared to grasslands, suggesting a reduced sensitivity of plant assemblages to bioclimatic variations in intensively managed habitats [44].…”

Higher functional resilience of temperate forests at intermediate latitudes of a large latitudinal gradient in South America

“…Concurrently, high trait variance suggests species' abilities to finely tune these traits to specific microhabitats 81 or respond to localised variations in resource availability 82 , contributing to the community's ecological diversity and resilience 83,84 within the Mediterranean ecosystems.…”

Macroecology of vegetation — Lessons learnt from the Virtual Special Issue

“…For plants, this Special Issue demonstrates that many studies and large initiatives have addressed this gap since then. A total of 15 contributions used fine‐grain plant community data to address macroecological questions at various extents: global (Kusumoto et al, 2021; Testolin et al, 2021), across the whole Palaearctic (Biurrun et al, 2021; Dembicz et al, 2021; Zhang et al, 2021), across Europe (Axmanová et al, 2021; Boonman et al, 2021; Padullés Cubino et al, 2021; Sporbert et al, 2021; Večera et al, 2021), larger parts of Europe (Cao Pinna et al, 2021; Wagner et al, 2021) or at state level (Bourgeois et al, 2021; Craven et al, 2021). Most of these studies rely on two large vegetation‐plot databases established and maintained by two working groups of the International Association for Vegetation Science (IAVS), the European Vegetation Archive (EVA; Chytrý et al, 2016) by the European Vegetation Survey (Axmanová et al, 2021; Boonman et al, 2021; Cao Pinna et al, 2021; Padullés Cubino et al, 2021; Sporbert et al, 2021; Večera et al, 2021; Wagner et al, 2021) and the GrassPlot database (Dengler et al, 2018) by the Eurasian Dry Grassland Group (Biurrun et al, 2021; Dembicz et al, 2021; Zhang et al, 2021).…”

“…Most of these studies rely on two large vegetation‐plot databases established and maintained by two working groups of the International Association for Vegetation Science (IAVS), the European Vegetation Archive (EVA; Chytrý et al, 2016) by the European Vegetation Survey (Axmanová et al, 2021; Boonman et al, 2021; Cao Pinna et al, 2021; Padullés Cubino et al, 2021; Sporbert et al, 2021; Večera et al, 2021; Wagner et al, 2021) and the GrassPlot database (Dengler et al, 2018) by the Eurasian Dry Grassland Group (Biurrun et al, 2021; Dembicz et al, 2021; Zhang et al, 2021). Testolin et al (2021) used data from the global vegetation‐plot database sPlot (Bruelheide et al, 2019), and four relied on regional data compilations (Bourgeois et al, 2021; Craven et al, 2021; Kusumoto et al, 2021; Tordoni et al, 2021). This pattern highlights that community efforts of collating extensive collaborative vegetation‐plot databases, such as EVA, sPlot and GrassPlot, have the potential to facilitate new research avenues (Bruelheide et al, 2019; Dengler et al, 2011; Wiser, 2016), often beyond the initial scopes imagined by the founders of these databases, not mentioning the aims of most original field workers.…”

“…The authors found indications that the evolutionary history of alpine plant communities might be more relevant for trait composition than environmental filtering by climate, since the biogeographic realm explained a bigger proportion of the variation than the two climate‐related factors in their models (vegetation zone and climatic group). Bourgeois et al (2021) provide an example of how anthropogenic processes can decouple natural trait–environment relationships. By relating CWMs of three leaf traits to growing season length in agricultural systems, they tested for differences between grasslands and croplands.…”