The effects of hemlock woolly adelgid (Adelges tsugae) damage on short-term carbon cycling in southern Appalachian eastern hemlock (Tsuga canadensis) stands
Nuckolls, April Elizabeth
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Hemlock woolly adelgid (HWA), Adelges tsugae, is an introduced forest pest that poses a serious threat to eastern hemlock (Tsuga canadensis) in North America. The main objective of this study was to assess the short-term effects of simulated HWA mortality on carbon cycling in southern Appalachian hemlock stands. Rapid infestation of hemlock also occurred during the course of this study providing a comparison. Simulated and actual HWA infestation increased hemlock litterfall by 10-fold and 5-fold respectively and decreased very fine root biomass by 34% and 36% respectively. Simulated HWA infestation decreased soil moisture 17%, increased bare soil respiration 32%, and decreased the contribution of the O horizon to soil respiration 52%. Changes in litter and O horizon quality were likely natural interannual variations, not the result of HWA infestation. HWA-induced reductions in hemlock populations will result in dramatic changes in C cycling, forest composition, and microclimate in the southern Appalachians.