Influence of a local bioclimatic gradient on wild bees in boreal forest clearcuts

Abstract Variation in wild bee assemblages along climatic gradients is still poorly known, particularly in eastern Canada. In this study, we assessed wild bee communities in forest stands that were recently clearcut along a latitudinal bioclimatic gradient. The analyses were conducted at two taxonomic levels: first at the genus level for bees as a whole (Anthophila) and then at the species level for bumble bees ( Bombus spp. Latreille) (Hymenoptera: Apidae). Coloured pan traps were used to catch bees and a point-intercept method was used to survey floristic composition at each site. Abundance and richness of Anthophila genera and abundance of bumble bee species were inversely related to latitude, but richness of bumble bee species was not, being instead associated with sections of the gradient. These results indicate that the relationship between wild bee diversity and latitude varies among taxa and that climate and floristic resources probably each play a role. Bombus terricola , a species of concern in eastern Canada, was found in relatively high numbers throughout the study area. To our knowledge, this study provides the first assessment of wild bees in clearcuts in the province of Quebec, showing a clear differentiation of the communities along a spatial bioclimatic gradient.