Limestone quarries are the most important refuge for a formerly widespread grassland butterfly
|Biodiversity & Conservation; Biodiversity Conservation; Calcareous grassland; CALCAREOUS GRASSLANDS; CLIMATE; CONSERVATION; early-successional stage; Entomology; HABITAT QUALITY; host-plant abundance; LEPIDOPTERA; MANAGEMENT; METAPOPULATION STRUCTURE; microclimate; patch connectivity; PATCH OCCUPANCY; PLEBEJUS-ARGUS; SPECIES RICHNESS
|INSECT CONSERVATION AND DIVERSITY
Calcareous grasslands have an outstanding value for nature conservation. However, during the last century, they have suffered from severe area loss, fragmentation and degradation. Here, we studied the influence of macroclimate, landscape quality and habitat quality on populations of the Silver-studded Blue, Plebejus argus, in calcareous grasslands and limestone quarries in a Central European landscape. Our study revealed that limestone quarries, especially those being actively managed, are the most important refuge for P. argus. Originally, the species was common in calcareous grasslands across the study area. More recently, however, patch occupancy was five times higher at quarries compared to calcareous grasslands and mean adult abundance nearly four times higher at occupied quarries than at occupied grasslands. The key driver of patch occupancy and adult abundance was a high abundance of the host plant. Adult abundance, additionally, increased with a sparse vegetation and a high cover of bedrock. The deterioration of habitat quality due to abandonment and decreasing grazing intensity has resulted in a strong decline of P. argus in calcareous grasslands. In contrast, quarries exhibit a very low successional speed due to their shallow soils. Hence, they are characterised by a high habitat quality for P. argus, i.e. dense stands of the host plant L. corniculatus, which grow on skeletal soils providing warm microclimatic conditions. Preserving limestone quarries with their early-successional stages is of crucial importance for the conservation of P. argus.
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checked on Feb 22, 2024