Functional trade-offs: exploring the effects of climate change and agricultural practices as drivers of field margin plant communities

AbstractOver the past decades, agricultural intensification and climate change have led to vegetation shifts in Europe. However, these impacts are often studied using meta-analyses at large scales, or using taxonomic diversity. Functional trade-offs linking traits responding to climate and farming practices are rarely analyzed, especially on large-scale empirical studies. Here we used a standardized yearly monitoring effort of agricultural field margin flora at the national scale to assess the spatio-temporal response of diversity and functional traits to climatic and agricultural variations. We examined temporal trends in climate, agricultural practices, plant species richness, and trait community-weighted means and variances across 555 sites in France between 2013 and 2021. We found that temperatures have increased while soil moisture has decreased, reflecting current climate change, whereas the intensity of agricultural practices did not show clear temporal trends over the past decade. Changes in plant communities were noticeable, especially as they relate to climate change, while the impact of agricultural practices was limited and mainly exerted through field margin management and to a lesser extent, fertilization. Mediterranean sites, vineyards and perennial species demonstrated reduced response to climatic variations. Our findings suggest that species adapted to climate change (including Mediterranean species) have increased in proportion and are spreading northward. Importantly, we identified functional trade-offs suggesting that these species are also the most vulnerable to intensive agricultural practices. We put these results into the conceptual framework of Grime’s CSR triangle and suggest that the convergence of climate change and the maintenance of a highly intensive agriculture could carry a risk of abrupt declines in floristic diversity of field margins, a concern that merits further attention.