Vertical Stratification and Co-Occurrence Patterns of the Psocoptera Community Associated with Eastern Hemlock, Tsuga canadensis (L.) Carrière, in the Southern Appalachians

Abstract

Of the more than 300 species of Psocoptera described in North America, 44 species have been documented on eastern hemlock, Tsuga canadensis (L.) Carrière, in the southern Appalachians. However, the distribution and co-occurrence patterns of these species throughout the tree canopy are unknown. This study was initiated to evaluate specimen abundance, species richness and species composition among three designated strata in the canopy of eastern hemlock, assess species for vertical stratification patterns, and determine if co-occurrence patterns of Psocoptera species are random or non-random. During this study, 27 species representing 18 genera and 10 families were evaluated. Psocopteran specimen abundance, species richness and composition differed among the lower, middle, and upper strata. Unique assemblages were identified in each stratum, indicating vertical stratification. The upper stratum of the canopy had five exclusive species, the middle had four exclusive species, and the lower stratum had 14 exclusive species. The co-occurrence pattern of Psocoptera species in the canopy of eastern hemlock was non-random.

Keywords

• Psocoptera
• eastern hemlock
• canopy arthropods
• co-occurrence
• vertical stratification