Limestone quarries are the most important refuge for a formerly widespread grassland butterfly

Abstract

1. Calcareous grasslands have an outstanding value for nature conservation. However, during the last century, they have suffered from severe area loss, fragmentation and degradation.2. 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.3. 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.4. 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.5. Preserving limestone quarries with their early-successional stages is of crucial importance for the conservation of P. argus.

Assembly of heterotrophic communities during spontaneous succession in quarries: invertebrates model groups and macromycetes

“…The exposed bedrocks, extreme microclimates, rugged relief, and rudimentary soil layer at such sites often radically differ from surrounding landscapes, forming islets of regionally rare conditions offering colonization and establishment potential for regionally declining or rare organisms depending on such conditions. In early stages of post‐excavation succession, such substrates are colonized by early successional specialists, which have declined in general rural landscapes across the world (Bobrek 2020; Kettermann & Poniatowski 2022; Münsch & Fartmann 2022), but even later succession stages can have conservation value and aesthetic appeal (Baczyńska et al 2018). Based on these observations, many authors warned against technical approaches to post‐excavation sites rehabilitation, which usually consist of leveling‐off terrain and planting a few woody species, and advocating more balanced approaches to restoration (Prach et al 2011; Moradi et al 2018; Kettermann & Fartmann 2023).…”

A comment on “International principles and standards for the ecological restoration and recovery of mine sites”—useful but limited

“…In Europe, this would mean coniferous forests in the north, evergreen woodlands or maquis in the south, steppes in the east, and deciduous broadleaved woodlands in the rest of Europe (Bohn et al 2000). However, initial and early successional stages shortly after a disturbance by mining, or intermediate successional stages with still limited tree establishment can be of great conservation value (Baasch et al 2012;Alday et al 2022;Münsch & Fartmann 2022). The European landscape is also heavily eutrophicated causing altered soil dynamics and shifts in species composition (Bobbink et al 2010).…”