Extinction debt in calcareous grasslands PLANT SPECIES EXTINCTION DEBT IN A TEMPERATE BIODIVERSITY HOTSPOT: COMMUNITY, SPECIES AND FUNCTIONAL TRAITS APPROACHES

Extinction debt in calcareous grasslands Destruction and fragmentation of (semi-) natural habitats are considered the main causes of biodiversity loss worldwide. Plant species may exhibit a slow response to fragmentation, resulting in the development of an extinction debt in fragmented plant communities. The detection of extinction debt is of primary importance in habitat conservation strategies. We applied two different approaches proposed in the literature to identify extinction debt in Southeast Belgium calcareous grasslands. The first method compared species richness between stable and fragmented habitat patches. The second explored correlations between current species richness and current and past landscape configurations using multiple regression analyses. We subsequently examined results generated by both methods. In addition, we proposed techniques to identify species that are more likely to support extinction debt and associated functional traits. We estimated a respective extinction debt of approximately 28% and 35 % of the total and specialist species richness. Similar results were obtained from both methods. We identified 15 threatened specialist species under the current landscap