A new study in the Lower Saxony region of Germany has shed light on the significance of limestone quarries for wild bee conservation.
The findings, published in the Journal of Applied Ecology, highlight the value of strong connections between quarries and calcareous grasslands – biodiversity hotspots that thrive on the region’s chalk or limestone soils.
Led by Dr Felix Kirsch from the Thünen Institute’s Institute of Biodiversity, a team of researchers say these often-neglected sites require local management to protect their ecological value, and that "landscape-scale restoration and conservation of dry grasslands is the most promising approach to promote endangered bee species through enhanced habitat connectivity."
What they found – and why it matters
The team conducted surveys across 19 mainly disused quarries near the town of Göttingen in central Germany, using hand nets to collect data on bee populations in the most flower-rich areas.
They identified 2,360 individual bees, which included 114 species – 35 of these are listed as endangered.
The study examined various quarry features – such as size, age, scrub cover and flower abundance – and assessed the role of the surrounding landscape.
Results showed that older quarries with strong connections to nearby calcareous grasslands supported more stable populations of endangered bees.
“Quarries provide valuable habitats for wild bees and other animals and plants that occur on the now rare calcareous grasslands,” says Kirsch.
Kirsch underscores the importance of maintaining large, old and flower-rich quarries, noting that “many wild bee species nest in the ground and often need open, sunny areas to do so.”
Heavily overgrown quarries lose these critical habitats, leading to lower bee populations, say the researchers.
"Our research supports keeping old quarries open,” says Thomas Alfert of Germany’s Nature and Biodiversity Conservation Union (NABU). “This can be achieved by local nature conservation organisations or landowners, for example by removing woody plants or extensive grazing.”
Active quarrying operations may also play a role in habitat maintenance, say Dr Annika Haß and Professor Catrin Westphal from Göttingen University, stressing the need from connectivity: “High connectivity between quarries and neighbouring calcareous grasslands is crucial. This makes it easier for bees to move between the two habitats.
"Preserving and restoring nutrient-poor grasslands and maintaining quarries are good ways to support and conserve wild bees.”
Find out more about the study: Landscape diversity, habitat connectivity, age and size determine the conservation value of limestone quarries for diverse wild bee communities
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