The influence of nest-site limitation on the species richness and abundance of bees : linking biodiversity and geology
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- Master’s theses (MINA) 
There is mounting evidence of declines in global biodiversity. Declining wild bee populations are subject to concern because bees are considered the most important pollinators worldwide, contributing to the production of agricultural crops and reproduction of wild plants. A suitable habitat for bees must include both foraging recourses and nesting recourses. While the link between flowers and bees has been shown innumerable times, the importance of nesting recourses is poorly documented. A large portion of the Norwegian bee fauna are solitary mining bees, because of their habits of not nesting on colonies and excavating subterranean nests in, most often, sandy soils. Due to enhanced nesting recourses for such mining bees, I hypothesised that sediment type would influence on the species richness and abundance of bees. To test this, I sampled bees in road verges on sediments with differing textures, comparing the bee fauna on glaciofluvial (sandy) versus marine (clayey/silty) sediments. The influence of sediment type was larger for the solitary compared to the social bees, and both the species richness of bees, as well as the species richness and abundance of solitary bees were higher on glaciofluvial compared to marine sediments. These results indicate nest site limitation as an important ecological factor influencing bee communities, implying that geological processes control the distribution of nesting recourses for mining bees in areas affected by glaciation processes.