HYMENOPTERA OF THE WAGNER NATURAL AREA, A BOREAL SPRING FEN IN CENTRAL ALBERTA

Abstract

AbstractThe Wagner Natural Area, located 8 km west of Edmonton, Alberta (53°34′N 113°47′W), contains a boreal spring fen estimated to be 4700 years old. The site was selected in 1985 for a survey of its arthropod fauna. A transect of the site from marl pools through fen, edge effect, and treed swamp was sampled for arthropods using pan and Malaise traps. Specialized microhabitats outside the transect were identified and sampled using pan traps. The Wagner fen samples contain 2181 species of arthropods contributing to a total known biota of 2905 species in the peatland. Of those, 1410 are Hymenoptera. Although seven other peatland studies are known, the inability of systematists to name most species prevents direct comparisons among peatlands. Data obtained from the Hymenoptera collections at Wagner demonstrate a progression in species richness as one approaches the forest–fen edge from either fen or forest. A large proportion [30% (382 species)] of Hymenoptera species, termed the aerial component, is active both in the forest–fen edge and in the fen. The aerial component is a highly mobile, at least locally transient, but often uncollected component of peatland ecosystems. Presence of the aerial component is probably associated with habitat structure. Those peatlands possessing more complex vegetation architecture have greater proportions of aerial species. About 80% of Hymenoptera at Wagner are parasitoids, most of which attack larva of holometabolous hosts. Based on the host groups sought by parasitoids and the ratio of parasitoid species per host species, the fen is estimated to contain about 6000 species of arthropods.