Exploring dynamics of floristic composition in Mediterranean grasslands: a case study from Sardinia, Italy

Abstract

Mediterranean grasslands stand out as biodiversity hotspots due to their inclusion of diverse habitats that foster a remarkable range of biological diversity, characterized by inter-annual variability of floristic composition. This study aims to assess the inter-annual dynamics of the floristic composition in a grassland within a typical silvopastoral system in the Mediterranean basin, within the framework of rainfall variability. The study was performed on a farm representative of Mediterranean silvopastoral systems in Central-Western Sardinia (Italy). Vegetation surveys started in the spring of 2018 and concluded in the spring of 2022. They were conducted annually in the spring (S) and winter (W) seasons, using the point quadrat method along eight permanent transects. The dynamics of floristic composition were compared within and between years in terms of variability of specific percentage contribution (CSP) of each plant species. The results highlighted substantial differences in the composition of plant assemblages between the two seasons (W vs S) and between surveys within each season for all a posteriori comparisons. Anthemis arvensis, Lolium rigidum, Festuca ligustica and Medicago polymorpha were the main discriminating plant species between seasons. Considering the discriminant species between the four winter surveys, we found a positive effect of August rain on Cynodon dactylon CSP and a negative one on Trifolium subterraneum CSP. Considering the spring surveys, we found a positive effect of January rain on L. rigidum and a negative effect on Plantago lanceolata. The rain affected the inter-annual dynamics of floristic composition in the Mediterranean grasslands. Other factors, such as temperature, remain to be investigated. Moreover, a more extended data series may allow us to strengthen our results.