Canopy and understorey insect communities of sugar maple and white pine forests of the south-central Great Lakes-St. Lawrence region

Canopy arthropods of eastern temperate forests in Canada are poorly known. Differences in abundance, diversity, and richness of selected taxonomic groups were compared between the canopy and the understorey for two dominant forest types in the region: white pine (Pinus strobus) and sugar maple (Acer saccharum). A bow-and-arrow technique was used to place flight-interception traps in the canopy at 18 sites, with paired understorey traps placed directly below for comparison. The greatest amount of variation in arthropod communities was explained by the position of the trap's collecting bottle (upper or lower). Community composition of selected taxa (102 taxonomic groups, hymenopteran families, mymarid genera, and cerambycid species) differed between heights and forest types. Measures of richness also varied according to height and tree species; combined sampling showed higher asymptotic richness than sampling at only one height or in one forest type, emphasizing the need to include different forest types and strata for biodiversity monitoring.