PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Changes in ecosystem response associated with hemlock woolly adelgid infestation and preemptive logging in southern New England.

Lux, Heidi^*,1, Orwig, David¹, Jefts, Sultana¹, Foster, David¹, ¹ Harvard University, Petersham, MA, USA

ABSTRACT- Selective elimination of dominant tree species by introduced forest pests may initiate dramatic changes in forest structure, composition, and ecosystem function. To examine ecosystem response to stress and mortality on hemlock Tsuga canadensis, by the introduced hemlock woolly adelgid (Adelges tsugae, HWA) and associated preemptive logging operations, we investigated ecosystem function over the last six years at 4 hemlock-dominated sites in southern New England. Sites included three infested stands, one of which was logged in 2002, and a control, uninfested site. We analyzed nitrogen dynamics with close-topped cores and resin ion capture, as well as microenvironmental changes of soil temperature and moisture. Nitrogen cycling and microclimate responses to adelgid infestation have recently declined, perhaps due in part to reductions in HWA populations resulting from cold winters in 2002 and 2003. In contrast, logged sites exhibited soil temperatures 1-3 degrees higher than unlogged stands, rates of net nitrification 5 to 10 times higher than infested and control sites, and more than twice the level of total inorganic N available as measured by resin capture. These results have important implications for land managers as intact systems, even when infested with HWA, exhibit greater homeostasis than systems logged for salvage.

Key words: hemlock wooly adelgid, nitrogen, salvage logging, new england forests