Plant Species Better Adapted to Climate Change Need Agricultural Extensification to Persist

Agricultural intensification and climate change have led to well-known vegetation shifts in agricultural landscapes. However, concomitant plant functional changes in agroecosystems, especially at large scales, have been seldom characterised. Here, we used a standardised yearly monitoring of > 400 agricultural field margins in France to assess the temporal response of vegetation diversity and functional traits to variations in climate and intensity of agricultural practices (herbicides, fertilisation and mowing) between 2013 and 2021. We observed clear temporal trends of increasing warming and aridity, but trends towards agricultural extensification were weak or nonsignificant. Our results showed functional changes in plant communities over time, driven mostly by climate change and suggested selective forces opposing climate change to agricultural intensification. This translated as a temporal decline of competitive and ruderal species in favour of stress-tolerant species, putting plant communities in agroecosystems in a difficult position to escape both climate and agricultural pressures at the same time.