Management matters: Bee communities in open and degenerate heathlands in Nordhordland UNESCO Biosphere Reserve

Land-use changes and agricultural intensification have been attributed as the main anthropogenic drivers of declines in insect pollinators. Anthropogenic coastal heathlands are one of the ecosystems that have suffered the most from these intensifications, as traditional management practices have discontinued and only 10% of last century´s coastal heathlands remain. We collected data during the field season of 2022 on pollinator communities with emphasis on bumblebees, in two different habitat types: open and degenerate heathlands in an UNESCO Biosphere Reserve in Western Norway. Here, we aim to get an insight into how pollinator communities may change as more heathlands are left without active management practices like prescribed burning and livestock grazing. Species composition varied between the two habitat types. Degenerate heathlands typically had a higher abundance of some relatively common species in Norway, like B. pratorum, while the red-listed species B. muscorum was recorded exclusively in open heathlands. B. jonellus was more abundant in degenerate sites despite being known to forage on Ericaceae. This may be due to an additional floral diversity and nesting/over-wintering sites here compared to the open sites. Further research should explore potential impacts of landscape characteristics like fragmentation and land-use change on the abundance and diversity of pollinators in heathlands.