Temporal and spatial variation in abundances of native bee species on an altitudinal gradient in southern Tasmania

Abstract

Bee assemblages were investigated in heathy coastal forest, shrubby dry sclerophyll forest, and shrubby subalpine forest near Hobart, in southern Tasmania, during spring, summer, and autumn between September 1996 and October 1997. Several taxa previously unknown from the state were encountered, including the first Tasmanian records of the halictid subfamily Nomiinae. Assemblages varied both temporally and spatially. Temporal variation within particular vegetation types was due to interspecific differences in flight periods. Spatial variation resulted from most species being restricted to one or two of these vegetation types, with species richness being substantially lower in the subalpine area than the two vegetation types at lower altitude. This variation also involved several species being more or less restricted to one habitat. In particular, Lasioglossum (Austrevylaeus pertribuarium) was a subalpine specialist while numerous species were more or less restricted to either coastal or dry sclerophyll forests. There was also an interaction between these two forms of variation, in the form of divergence in the flight periods of individual species in different vegetation types.