Effects of forest loss and fragmentation on pollen diets and provision mass of the mason bee,Osmia cornifrons,in central Japan |
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| Authors: | TERUYOSHI NAGAMITSU MIKI F SUZUKI SHOTARO MINE HISATOMO TAKI KATO SHURI SATOSHI KIKUCHI TAKASHI MASAKI |
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| Affiliation: | 1. Hokkaido Research Center, Forestry and Forest Products Research Institute, Sapporo, Japan;2. Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan;3. Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Japan;4. Forestry and Forest Products Research Institute, Tsukuba, Japan;5. Tama Forest Science Garden, Forestry and Forest Products Research Institute, Tokyo, Japan |
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| Abstract: | 1. Habitat loss and fragmentation potentially affect the performance of bees that forage nectar and pollen of plants in their habitats. In forest landscapes, silvicultural conifer plantations often have reduced and fragmented natural broadleaf forests, which seem to provide more floral resources for bees than do the plantations. 2. This study evaluated the effects of forest characteristics (i.e. elevation, area, edge length, and tree size of natural forests) on pollen diets (plant taxa assemblages of pollen grains in provisions) and total provision mass in oviposited chambers in nests made by a standardised number of Osmia cornifrons bees at 14 sites in a forestry area in central Japan. 3. From April to May, the numbers of nests and chambers per nest increased, and the provision mass per chamber decreased. Main pollen sources were Prunus at higher elevations in April and Wisteria at lower elevations in May, foraging on which increased the numbers of nests and chambers per nest. The provision mass per chamber was smaller at higher elevations in more fragmented natural forests. Decreases in the area of natural forests within the foraging range (400‐m radii) of O. cornifrons increased the utilisation of Rubus pollen and decreased the total provision mass. 4. These findings suggest that the loss and fragmentation of natural broadleaf forests change pollen diets and reduce the provision mass of mason bees, which may reduce the number and size of their offspring. |
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| Keywords: | Broadleaf forest conifer plantation habitat fragmentation habitat loss Megachilidae spatial scale |
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