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Harvard Forest Research

Changes in insect diversity following hemlock decline

Principal Investigator: Aaron Ellison
Harvard Forest: May 01 2005 - Jan 01 2010:

Abstract:
Impacts of invasive species in general, and of the hemlock woolly adelgid (HWA) in particular, on the structure of the invaded communities are not well understood. We hypothesize that if other taxa are restricted to hemlock forests, or if dominance by hemlock precludes the colonization or occurrence of certain species, then removal of hemlock could result in changes in overall species diversity and composition within HWA-infested stands and across the landscape. We are testing this hypothesis using forest ant and beetle communities in the Simes Hemlock removal experiment. Specifically, we ask how insect species richness and composition differs among the treatments (control, girdle, log) and hardwood controls. A major focus of the work in summer 2006 is to continue long-term monitoring in the Simes experimental plots, and to expand the biodiversity inventory to the entire Simes Tract so that we can determine if diversity patterns in the experimental plots is representative of the tract.

Update 2007: Having successfully completed a Simes-wide inventory of ants in summer 2006, we will restrict our sampling in 2007 to the hemlock manipulation plots (and hardwood controls). In addition to continued monitoring of changes in ant species composition, we will focus additional attention on understanding the distribution and abundance of the six-spotted tiger beetle (Cicindela sexguttata, which colonized the logged plots in 2006. This beetle preys on other insects, and may alter population structure of ants and other beetles in the logged plots. It may also begin to colonize the girdled plots as they continue to deteriorate.

Update 2008 We will continue sampling of ants and carabids in 2008 in the 8 Simes plots only. We will also save spiders from pitfall traps for id by Clarisse Hart

Update 2009 Participant Israel del Toro, new UMass graduate student working with PI Ellison, will join this project in May 2009. In 2009, he will have primary responsibility for sampling of ants and carabids in the 8 Simes plots. Clarisse Hart will continue spider inventory.: