Bumblebee communities in open and overgrown heathlands in Nordhordland UNESCO Biosphere, Vestland, Norway
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- Master theses 
Insect pollinators such as bumblebees (Bombus spp.) play a vital role in the pollination of wild and cultivated plants and is therefore critical for ecosystem services and food security worldwide, especially in northern ecosystems. However, declines in pollinators have been reported due to anthropogenic drivers such as land use change and agricultural intensification. This study aims to investigate communities of Bombus species in open and overgrown heathlands in a UNESCO Biosphere Reserve in Vestland, Norway. Pan traps and insect aerial nets were used to effectively capture pollinators in six study sites during two distinct sampling periods: June and August. A total of nine Bombus species were identified, with the most abundant being B. lucorum complex, B. jonellus, and B. pascuorum, which accounted for 71% of the individuals. Species composition varied between the sites. The overgrown heathlands typically had a higher abundance of habitat generalists like B. pratorum, while the specialist and red-listed species B. muscorum were recorded exclusively in open heathlands. The sampling period was a significant predictor of B. muscorum abundance. B. jonellus however, was more abundant in overgrown sites despite being a specialist on Ericaceae, which may be due to the additional floral diversity and nesting sites found here. Further research should explore the potential impacts of landscape characteristics like fragmentation and management practices on the abundance of Bombus in heathlands. Habitat conservation is considered the most effective way to conserve insect pollinators and should be highlighted in policy-making decisions to maintain healthy populations.