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Effects of green-tree retention on abundance and guild composition of corticolous arthropods

Formally Refereed

Abstract

We studied the effects of varying levels and patterns of green-tree retention on the community composition of bark-dwelling arthropods. Arthropods were sampled with crawl traps installed on 280 live trees and 260 snags (all Douglas-fir) at three locations (experimental blocks) in the western Cascade Range of Oregon and Washington. Sampling coincided with the breeding season of the brown creeper (Certhia americana), a primary avian predator, in 2003 and 2004. Pattern of retention did not affect abundance of most arthropod groups, although two families of spiders (Linyphiidae and Thomisidae) were more abundant in dispersed than in aggregated treatments. Traps on live trees yielded 2.2 times more arthropods than did traps on snags likely reflecting differences in food resources. A high proportion of herbivorous taxa showed negative associations with local density and basal area of overstory trees and positive associations with cover of herbs, suggesting that many corticolous arthropods originate in the understory and respond positively to increases in vegetation cover following retention harvests. The numerical dominance of Collembola and high abundance of Diplopoda also suggest important ecological ties between communities of corticolous and detrital (litter-dwelling) arthropods.

Keywords

arthropod community structure, avian food resources, brown creeper (Certhia americana), tree bark, trophic interactions, variable-retention harvest

Citation

Halaj, Juraj; Halpern, Charles B.; Yi, Hoonbok. 2009. Effects of green-tree retention on abundance and guild composition of corticolous arthropods. Forest Ecology and Management. 258: 850-859.
https://www.fs.usda.gov/research/treesearch/34866