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Harvard Forest Symposium Abstract 2014

  • Title: Effects of winter climate change on stem and belowground carbon dioxide efflux in a mixed-hardwood forest
  • Primary Author: Pamela Templer (Boston University)
  • Additional Authors: Stephanie Juice (Boston University); Andrew Reinmann (Boston University); Patrick Sorenson (Boston University); Amy Werner (Boston University )
  • Abstract:

    Climate models project winter warming in the northeastern United States of approximately 4 °C and a significant decrease in the depth and duration of the winter snow pack by the end of the 21st century. In the absence of an insulating layer of snow, soils can freeze when air temperatures drop below freezing. In recent years, considerable progress has been made in our understanding of how soil microbial activity and nutrient cycling might respond to reduced snow cover and increased soil frost. However, the response of growing season plant dynamics to changes in the winter snowpack is less well understood. The objectives of this research are to determine the impacts of changes in the winter snowpack and increased soil frost on growing season ecosystem dynamics such as sap flow, stem efflux of trace gases and soil respiration. We conducted a snow-removal experiment in mixed stands of red maple (Acer rubrum) and red oak (Quercus rubra) at Harvard Forest in Petersham, MA. Snow was removed for the first 5 weeks of winter to mimic a later onset of the snowpack. Snow-removal induced soil frost and led to significantly lower soil temperatures compared to the reference stands. The results of our multi-year study suggest that a later accumulation of snow and greater depth and duration of soil frost decreases rates sap flow and canopy carbon exchange in the early growing season, with a larger effect on red maple compared to red oak trees. Our results illustrate the importance of examining the impacts of changes in winter climate on plant dynamics during the growing season because there could be feedbacks to future climate.

  • Research Category: Forest-Atmosphere Exchange, Soil Carbon and Nitrogen Dynamics