Mediterranean Grassland Succession As an Indicator of Changes in Ecosystem Biodiversity and Functionality

The abandonment of agricultural lands triggers a secondary succession of plant species which implies important changes in soil quality. Annual Mediterranean grasslands are known to be persistent on abandoned agriculture lands in the western Mediterranean. We used plant taxonomic and functional approaches to determine the role of Mediterranean grasslands as an indicator of changes in ecosystem biodiversity and functionality. We tested the hypothesis that Mediterranean grasslands are a suitable model for monitoring biodiversity and soil fertility in a secondary succession. Soil and vegetation features on 21 permanent plots were monitored in 2016 and 2020. Numerical classifications based on floristic composition showed two different plant communities independently of the sampling year: early-stage grasslands in the first post-abandonment decade and late-stage grasslands after the first post-abandonment decade. Generalized linear model and redundancy analysis also revealed differences in growth forms, functional traits and soil functionality between communities. Late-stage grasslands was characterized by enriched bryophyte coverage and an impoverishment in hemicryptophytes and plant latex segregators growing on soils with a higher hydrolase enzyme activity and TOC content compared to early-stage grassland. Our results suggest that annual Mediterranean grasslands growing on siliceous soils denoting a mature-stage succession, and floristically characterized by the symbiont plant with Ascomycota, Tuberaria guttata , and a high bryophyte cover, are worthy of recognition for conservation.