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Harvard Forest REU Symposium Abstract 2013
- Title: Hemlock woolly adelgid’s impact on foliar and root microbial abundance in eastern hemlock stands
- Author: Justin F Vendettuoli (University of Rhode Island)
- Abstract:
Eastern hemlock, Tsuga canadensis, is an integral species contributing to the ecosystem heterogeneity across many northeastern landscapes. An invasive insect, the hemlock woolly adelgid (HWA; Adelges tsugae), has been devastating in hemlock stands by parasitizing the hemlock, eventually leading to needle loss and tree mortality. The adelgid creates a unique woolly by-product to protect its eggs that can cover branches resulting in a considerable influx of wool in heavily invested stands. There is a need to better understand how the system is altered as infestation progresses, especially with regards to changes in foliar and belowground or soil processes. To assess the impact of HWA, we measured bacterial abundance on foliage and fine roots from three trees each at 10 infested and 10 control sites across central MA. We also determined C:N ratio of woolly by-products and fine roots to examine how that may affect bacterial abundance. I predicted to find higher bacterial abundance on infested foliage and roots based on previous research on foliage. Woolly by-products were found to have high nitrogen (mean of 2.6% N), which may promote bacterial growth. Fine root percent N did not differ between treatments (0.98 – 1.02%), but percent C was modestly but statistically (P=0.0003974) higher in control (50.98%) vs. infested (50.19%) fine roots. Our results will contribute to an emerging conceptual model of how adelgid infestation affects above and belowground processes in hemlock stands, even before tree mortality.
- Research Category: Invasive Plants, Pests & Pathogens
