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Harvard Forest Symposium Abstract 2018

  • Title: Increased water yield due to the hemlock woolly adelgid (HWA) infestation observed at Harvard Forest
  • Primary Author: JiHyun Kim (Indiana University - Bloomington)
  • Additional Authors: Emery Boose (Harvard Forest); Taehee Hwang (Indiana University - Bloomington); J. William Munger (Harvard University); David Orwig (Harvard Forest); Crystal Schaaf (University of Massachusetts - Boston)
  • Abstract:

    Over the past few decades, a hemlock woolly adelgid (HWA) infestation has significantly affected eastern hemlock (Tsuga canadensis) in the eastern US, and warmer winters are expected to promote a continued northward expansion in the future. While much research has been conducted examining terrestrial changes associated with HWA, less is known about the impact of HWA on aquatic systems. We examined evapotranspiration measured at the hemlock eddy flux tower and performed a paired catchment analysis by examining monthly stream discharge data from the Bigelow Brook Catchment (newly called Arthur’s Brook) and the Nelson Brook Catchment. The mechanistic ecohydrological model RHESSys was then used to assess the magnitude of net changes in water yield due to HWA infestation. We found, for the first time in New England, a water yield increase due to the HWA infestation. Since the first observation in 2002, peak growing season evapotranspiration over the hemlock-dominated area has decreased by 24-37% in 2012 and 2013. Over the same time period, the water yield from the study catchment significantly increased as compared to an adjacent catchment with less hemlock cover. The net increase was estimated to be as much as 15.6% of annual water yield in 2014 based on an ecohydrological modeling analysis. This study indicates that the ongoing hemlock decline is also largely altering hydrological regimes in the northeastern US.

  • Research Category: Watershed Ecology; Invasive Plants, Pests & Pathogens; Forest-Atmosphere Exchange