PARENT SESSION
Poster Session #31: Climate Change.
Wednesday, August 8, 2001. Presentation from 3:30 PM to 5:00 PM. Exhibition Hall
94
Warming and clipping effects on microclimate in tallgrass prairie: its implications for global warming and land-use change.
WAN, SHIQIANG1, LUO, YIQI1, WALLACE, LINDA1, 1
ABSTRACT- In this study, infrared heaters and clipping were used to mimic global warming and mowing/grazing, respectively, with an attempt to examine their impacts on microclimate and to validate the infrared heater in warming tallgrass prairie. The results showed that infrared heaters are an efficient means of manipulating temperature and successfully simulated the mechanism and diurnal pattern of air temperature under global warming, i.e., augmentation in downward infrared radiation and greater increase in daily minimum than maximum air temperature. The enhanced downward infrared flux is more effective in heating soil than air. Warming significantly increased daily mean and minimum air temperatures by 1.1 °C and 2.3 °C, respectively, but had no effect on daily maximum air temperature, thus caused substantial decrease in the daily range of air temperature. Solar radiation, wind speed, relative humidity affected the responses of air temperature to enhanced infrared flux. Warming enhanced soil temperature substantially whereas clipping increased daily maximum and mean soil temperatures, but decreased minimum soil temperature. Warming caused a 10.5 % reduction in soil moisture in the clipped subplots but did not affect soil moisture in the unclipped subplots. Clipping reduced soil moisture by 17.3 % and 23.7 % in the control and warmed plots, respectively. The results of our experiment indicated that tallgrass prairie would likely be a net source of atmospheric CO2 and provide a positive feedback to global warming.
KEY WORDS: Global Warming, Infrared heater, Clipping, Tallgrass Prairie