Plant adaptive strategies respond to environmental change across European grassland habitats

Grassland ecosystems are facing rapid and ongoing change driven by intensified land-use and accelerated climate change, highlighting the urgent need to understand their potential adaptation and response to environmental change. We analyzed data from 52 980 vegetation plots spanning all major grassland habitats in Europe (including alpine, rocky, sandy, saline, dry, mesic and wet grasslands). We quantified competitive (C), stress-tolerant (S), and ruderal (R) strategies for 7858 plant species based on key functional traits and mapped the spatial patterns of C-, S- and R-strategies across European grasslands. Using random forest models, we evaluated the relative importance of environmental factors in shaping these patterns and explored potential changes in the distribution of C-, S- and R-strategies under future climate scenarios. We further investigated how these strategies and their environmental drivers vary across grassland habitats. Our results revealed a clear biogeographical gradient in the distribution of C-, S- and R-strategies from predominantly stress-tolerant strategies in Mediterranean grasslands to greater representation of competitive and ruderal strategies in temperate regions. Climate and soil factors emerged as major drivers shaping these patterns at the continental scale. Projected responses to future climate change varied among regions: grasslands in the Atlantic and Continental regions were projected to decrease in C-strategy and increase in both S- and R-strategy representation, whereas grasslands in Arctic and boreal regions exhibited contrasting trends. Mediterranean grasslands were projected to undergo a transition from mainly R-strategy toward S-strategy species predominance. Furthermore, the strategy patterns and their key drivers differed among grassland habitats, with patterns largely reflecting habitat-specific environmental constraints. This study demonstrates the utility of Grime's CSR framework for characterizing broad-scale patterns of plant adaptive strategies across diverse grassland habitats. It highlights region- and habitat-specific differences in potential responses to future climate change, with implications for targeted grassland management and restoration.