PARENT SESSION
Poster Session # 19: Insect and Invertebrate Ecology.
Thursday, August 7 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
When a tree falls in the forest: Resource concentration after forest management benefits bark beetles.
Simpson, Colleen*,1, Reid, Mary1, 1 Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
ABSTRACT- The resource concentration hypothesis (sensu Root 1973) predicts that herbivores will be most abundant in areas of high host species concentration (large patches of low vegetational diversity). Here, we apply the resource concentration hypothesis to explain increased pine engraver bark beetle (Ips pini (Say); Scolytidae) abundance in thinned stands, as compared to natural stands. Forest thinning, the selective harvest of a proportion of trees, results in changes to the biotic and abiotic characteristics of the remaining stand. After thinning, stands become more open, evenly spaced, and dominated by a single tree species. Increased wind speeds in thinned stands may contribute to the observed increase in input of freshly downed trees. We found pine engravers to be more abundant in thinned lodgepole pine stands, even up to seven years after thinning harvest. The resource concentration effects of thinning (greater input of host material with less non-host material) is a novel explanation for the increased abundance of secondary bark beetles in thinned boreal forest stands.
Key words: herbivore abundance, resource concentration, forest thinning, Ips pini