Chronicle of a death foretold: the vanishing of an emblematic cultural landscape results in the loss of its unique plant communities

Badlands are peculiar geomorphological formations shaping landscapes of high ecological and cultural value. In the last decades, land reclamation for agricultural purposes and the ceasing of traditional land use, such as sheep grazing, led to their decline in extent in many areas. To quantify the changes in badland-related plant communities, we resurveyed badland vegetation in a site of the Crete Senesi (Siena, central Italy) after 16 years (2006-2022), using 48 quasi-permanent vegetation plots and by means of uni and multivariate analysis of variance. We found an increase in the total vegetation cover of plant communities growing in former bare soil and sparsely vegetated areas, consistently with an overall decrease in the extent of bare soil surfaces in the study area, which we highlighted by analyzing multitemporal satellite images. Pioneer vegetation characterized by the endemic plant Artemisia caerulescens subsp. cretacea changed into ruderal annual grasslands, while former bare soils were colonized by such pioneer vegetation. Conversely, perennial grasslands were highly stable. Grasslands with shrubs became more similar to grasslands in species composition. Species richness increased in former bare soils. Using the total vegetation cover as a proxy for successional stages, we found that Shannon diversity and evenness peaked at about 90% of total cover. In all the stages of colonization, short distance dispersal species prevailed, both therophyte (Avena sterilis, Parapholis strigosa) and perennial (A. caerulescens subsp. cretacea, Bromopsis erecta). Long distance dispersal species (Galatella linosyris) start colonizing at about 60% of total vegetation cover, and at high vegetation cover all the functional groups coexisted. Our results confirm that the badland landscapes of southern Tuscany and badland-specialist plant diversity are vanishing after changes in land management, suggesting the current ineffectiveness of the Natura 2000 network in their conservation.