Production and nutrient cycling in temperate ecosystems: How winter climate matters

Climate  exerts  strong  controls  over  plant  growth  and  nutrient cycling, but the mechanisms underlying climate responses have mainly been studied over the growing season. However, winter processes can also play an important role in driving ecosystem responses, and northern temperate regions in particular are sensitive to variability in winter climate. I examined projections of soil freezing responses to climate change using a variety of modeling, observational and hindcasting approaches. Overall, despite a general pattern of a decreased numbers of days of frozen soil and decreased numbers of days with snow on the ground, projected responses of soil freezing dynamics to climate change have been regional in nature, and many northern temperate regions are expected experience an increased number of soil freeze thaw cycles as a result of reduced snow cover. The responses of plants and nitrogen dynamics to changes in soil freezing are sensitive to the timing, frequency, length and severity of soil freezing. I have conducted a range of laboratory, mesocosm and field experiments to examine the important thresholds inherent in these responses, and to assess how freezing damage may interact with increases in atmospheric N deposition over the next century.

Friday, March 28, at 3:30pm Alexander Hall Room 218