Abstract: In order to clarify the species and ecological niche of flowervisiting insects in Xiangyun Basin in winter, we investigated the pollinators who visited oilseed rape (Brassica chinensis), cabbage mustard (Brassica alboglabra), and broad bean (Vicia faba) on the field during December 2015 to January 2016. We recorded pollinator species, headage, visiting frequency and settling time at intervals of 30 min in one day per week, and analyzed the pollinator composition and niche characteristics (niche breadth and niche overlap). The results showed that the pollinators were mainly from Hymenoptera and Diptera, and honeybees (including Apis mellifera and Apis cerana) and flies (Musca domestica and Eristalis tenax) were the dominant species. The peak visiting time had interspecific difference, and most species visited flowers during 11:00-15:30 on the day. The pollinators also made interspecific difference in settling time (F_2,862=13.43, P<0.01), with the longest for M. domestica (32.80±2.56 s), and the shortest for A. mellifera (9.91±0.40 s). The pollinators had the maximum visiting time on oilseed rape (16.50±0.82 s), and the minimum on broad bean (10.31±1.14 s). There was a difference in niche breadth among pollinators, with the greatest for A. mellifera (Levins’ niche (Bi)=0.8345, Hurlbert’s niche (Ba)=0.3074). Moreover, niche overlap was higher in intraspecies but smaller in interspecies, being 0.8451 between A. cerana and A. mellifera, and 0.0928 between A. cerana and M. domestica. We conclude that the different peak visiting time of pollinators can decrease the competition of collecting limited food resource in winter. The honeybees have higher niche breadth on pollination and thus are the dominant pollinators; however, the niche overlaps are higher in the intraspecies, which makes a stronger competition pressure. Higher niche overlaps between honeybees may explain the disappearance phenomenon of native bee A. cerana after the introduction of exotic bee A. mellifera.

Key words: public welfare forest, compensation standard, ecological compensation, compensation method.