Subnivean arthropod fauna of southeastern Wyoming: habitat and seasonal effects on population density

Subnivean arthropods were studied in a mosaic of plant communities (lodgepole pine Pinus contorta Doug.; aspen Populus tremuloides Michx.; sagebrush Artemisia sp.; and meadow) in southeastern Wyoming. Subnivean arthropods were collected weekly in modified pitfall traps from 22 November 1987 through 6 April 1988. A total of 91 species from 13 orders in three classes were collected in this survey. The orders Collembola, Coleoptera, Acari and Araneae comprised 98% of all individuals and 76% of all species collected. These orders showed significant differences in abundance across time and habitat types. Aspen and conifer habitats generally supported the greatest numbers of subnivean arthropods, although collembolans were extremely abundant in meadows during early spring. Across all habitats, the greatest arthropod abundance occurred during late autumn and early winter. Individuals of some taxa were active during midwinter (e.g., Collembola in aspen habitats), although few species were active exclusively during this period.