Abstract :
[en] Climate change is expected to reshape the seasonal rhythm of grassland productivity across temperate Europe. Using the process-based model Gras-Sim, this study assessed how future warming and associated CO₂ trajectories (+2°C, +3°C, +4°C) may alter the intra-annual distribution of biomass yield in permanent grasslands. Simulations were conducted for contrasting pedoclimatic regions of Wallonia, combining downscaled CMIP6 projections (CMCC, MIR, MPI) with site-specific soil and management parameters. Results indicate a pronounced seasonal redistribution of productivity rather than a uniform annual response. Spring yields consistently increased across all models and warming levels, reaching up to 4.5 t DM ha-1 relative to the historical baseline (1981-2010) under the MIR +4°C scenario (P < 0.001). In contrast, summer yields declined in all simulations, with losses up to -2.4 t DM ha-1, while autumn responses were more variable across regions and models. Regionally, cooler high-altitude areas exhibited the most stable seasonal profile, spring gains of +2.60 ± 1.51 t DM ha-1, limited summer losses of -0.93 ± 0.99 t DM ha-1, whereas drought-prone lowlands on sandy or clay-limestone soils experienced stronger summer declines, reaching up to -1.46 ± 1.15 t DM ha-1. These findings highlight a shift toward earlier growth and reduced summer resilience, reflecting the interaction between warming, soil water availability, and phenological advancement. Seasonal shifts in productivity thus emerge as a key dimension of grassland vulnerability, emphasizing the importance of adaptive management to sustain forage supply under future climates.
