New Harvard Forest Publication: Foliage Decomposition in Forests Affected By Hemlock Wooly Adelgid

Recent Research Assistant Richard Cobb, working with collaborators including Harvard Forest Ecologist David Orwig and former HF Summer Reserach Program student Steve Currie, examined the impacts of the introduced insect, the hemlock woolly adelgid (HWA) on green litter decomposition in New England hemlock forests. This study investigated both the direct effects of HWA feeding and indirect changes in microclimate on foliar decomposition. Results suggest that while HWA-feeding did not result in significant changes in foliar percent carbon (C), percent nitrogen (N), or percent lignin at the beginning of the study, decomposing foliage from infested trees had significantly higher N concentrations than uninfested foliage as decomposition progressed. Mass loss of uninfested foliage was lower in infested hemlock stands than uninfested stands (30.9% ±0.7% vs. 34.2% ± 0.1%). Rates of mass loss were significantly correlated with microclimate factors and indicate that organic soil moisture levels are controlling decomposition in HWA-infested forests. 

Cobb, R.C., D. A. Orwig, and S. Currie. 2006. Decomposition of green foliage in eastern hemlock forests of southern New England impacted by hemlock woolly adelgid infestations. Canadian Journal of Forest Research 36: 1331–1341.