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Harvard Forest Symposium Abstract 2005

  • Title: Response of soil respiration to rain in a temperate, hardwood forest in Massachusetts
  • Primary Author: Hui-Ju Wu (Yale University)
  • Additional Authors: Xuhui Lee (Yale University)
  • Abstract:

    Rain simulation field experiment was conducted on the Prospect Tract of Harvard Forest, Petersham, Massachusetts. Soil CO2 flux increases rapidly and instantaneously upon the onset of rain and returns to the pre-rain rate soon after rain stops. The pulse-like response of soil respiration to rain could easily be missed if measurements are not taken during the rain. Soil CO2 flux is generally greater on plots with litter layer than on plots without litter layer. However, flux enhancement due to rain simulation does not show significantly different patterns between these two sets of plots. There is a weak linear relationship (r2 = 0.2) between flux enhancement ratio and soil moisture increment on litter plots. The regression suggests that flux enhancement is greater on litter plots than on no-litter plots when moisture increment is less than 8 % (vol), and becomes the opposite when moisture increment is greater than 8 % (vol). Our preliminary observation suggests that initial soil moisture conditions may be a factor that influences the magnitude of the response of soil respiration to rain. The contribution of litter to CO2 flux shows a negative correlation with litter layer moisture, which is contrary to our previous results at a relatively well-drained site at Great Mountain Forest, Norfolk, Connecticut. This may also be an indication that this is a site with excessive soil moisture and water is not a limiting factor for soil respiration here. With precipitation becoming more variable in the future due to global climate change, this field study, combined with eddy covariance measurements and laboratory incubation experiments, aims to contribute to a better understanding of effects of precipitation on soil respiration, more precise annual net ecosystem production (NEP) and feedback of the climate system via the terrestrial carbon cycle.











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