PARENT SESSION
Poster Session #35: Decomposition and Soil Respiration.
Thursday, August 9, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall

The effects of hemlock woolly adelgid infestation on foliar decomposition in eastern hemlock forest of southern New England.

COBB, R¹, ORWIG, D¹, CURRIE, S¹, ¹

ABSTRACT- Stands dominated by eastern hemlock (Tusga canadensis) are cool and deeply shaded ecosystems found throughout the New England landscape. Infestation by the hemlock woolly adelgid (Adelges tsugae, HWA), an exotic forest pest, currently threatens to eliminate hemlock as the dominant tree species in these forests. As part of a study examing the timing, magnitude, and duration of ecosystem function changes associated with infestation by this insect we examined decomposition of eastern hemlock litter at 8 sites in southern New England. Decomposition was examined in-situ for 18 months in sites ranging from zero to heavy infestation. We placed two sets of hemlock litter at each study site, one set collected from infested stands and one set from an uninfested control. Sites with heavy canopy damage typically had 9% more mass remaining than low damage and non-infested sties at the end of measurements. These sites tended to have higher % open sky and soil temperatures. Litter from infested sites had 10% more mass remaining relative to uninfested foliage however, neither set of foliage accumulated C or N at different rates. This suggests a subtle difference in foliar quality exists between the two types of foliage that was not detected in this study. The results of this study suggest that both the direct effects of herbivory and forest microenvironmental changes associated with infestation may alter decomposition in these forests for many years.

KEY WORDS: Decomposition, Hemlock Woolly Adelgid, Ecosystem Function, C