Diversity and Distribution of Oribatid Mites (Acari: Oribatida) Associated with Arboreal and Terrestrial Habitats in Interior Cedar-Hemlock Forests, British Columbia, Canada

Abstract

We assessed oribatid mite abundance, species richness and community composition in arboreal and terrestrial habitats associated with 12 western redcedar trees in the Interior Cedar-Hemlock biogeoclimactic zone of British Columbia, Canada. We extracted microarthropods from 36 canopy litter samples, 36 epiphytic lichen samples from three different lichen functional groups, and 36 soil core samples of the forest floor litter layer. Oribatid mites dominated microarthropod assemblages in all habitats. Total microarthropod and oribatid mite abundances were significantly greater in forest floors and foliose (leaf-like) lichens compared to canopy litter accumulations, and alectorioid (hair-like) and cyanolichen (lobed) groups. Sixty-one species of oribatid mites were identified from the study area. The ten species collected from canopy litter and 14 species collected from epiphytic lichens shared five species in common, whereas only three of the 45 species collected from the forest floor also were found within the canopy system. Principal components analysis and discriminant function analysis differentiated three distinct assemblages of oribatid mites corresponding to the canopy litter accumulations, epiphytic lichens and forest floor habitats. Low abundance of oribatid mites in canopy litter accumulations is attributed to low microhabitat structural complexity, low food resources and low desiccation resistance in these habitats compared to canopy lichen habitats and the forest floor. Epiphytic lichens are the domi nant habitat for arboreal oribatid mites in the ICH forest zone, and contribute to the overall biodiversity of the forest system by containing distinct oribatid mite assemblages.