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 cessation 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 quasipermanent 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, in line with an overall decrease in the extent of bare soil surfaces in the study area, which we highlighted through the analysis of 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. In contrast, perennial grasslands remained stable. Grasslands with shrubs became more similar to perennial grasslands in species composition. Species richness increased in former bare soils, and 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 therophytes (Avena sterilis, Parapholis strigosa) and perennials (Artemisia caerulescens subsp. cretacea, Bromopsis erecta). Long distance dispersal species (Galatella linosyris) started 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 specialist plant diversity adapted to badlands are vanishing after a diminishing of active land management, suggesting the current ineffectiveness of the Natura 2000 network in their conservation.