Temporal trajectories of plant functional traits in mediterranean grasslands under different grazing regimes

Aims Mediterranean grasslands are semi-natural ecosystems that have been affected by land-use intensification and abandonment during the past decades. Adaptative multi-paddock grazing regimes, where grazing alternates with long periods of vegetation recovery, have been proposed as a more biodiversity-friendly management compared with continuous grazing. This study aimed to compare the effect of these two different grazing regimes on a set of plant traits in mediterranean grassland vegetation over time. Location Central part of Sardinia (Italy) at 350 m a.s.l. in a permanent grassland system. Methods We applied the point quadrat method to quantify the specific contribution of each species along permanent transects in spring and winter from 2018 to 2022. We considered the following plant traits: leaf dry matter content, life forms, flowering start and length of flowering. Overall, we performed 128 surveys and measured traits for 61 species. We ran a linear mixed model to test the effect of season, grazing regimes and years on functional diversity and community-weighted mean for single traits. Results Adaptative multi-paddock regimes over time increased the leaf dry matter content. However, compared with grazing regimes, seasonality through time had the greatest effect on flowering traits and life forms. Conclusion The relatively small variation in the plant traits suggests that the mediterranean grassland was rather stable despite wide variation in grazing regimes, probably linked to their long history of human association. Nonetheless, adaptative multi-paddock regimes may have higher beneficial effects compared with continuous grazing, favouring more palatable species and improving soil fertility. By contrast, the high variation in the plant traits over time suggests a high vulnerability of the same grassland to climatic changes.