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EFFECTS OF CO2 AND O3 IN PONDEROSA PINE PLANT/LITTER/SOIL MESOCOSMS
Citation:
Olszyk, D M., J W. Gregg, M G. Johnson, D L. Phillips, R J. Seidler, D T. Tingey, AND L S. Watrud. EFFECTS OF CO2 AND O3 IN PONDEROSA PINE PLANT/LITTER/SOIL MESOCOSMS. Presented at International Union of Forest Research Organizations (IUFRO), Houghton, WI, May 28-31, 2000.
Description:
Forested ecosysems are subjected to interacting conditions whose joint impacts may be quite different from those from single factors. To understand the impacts of CO2 and O3 on forest ecosystems, in April 1998, we initiated a four-year study of a Ponderosa pine seedling/soil/litter system in special outdoor sun-lit chambers. Three hypotheses are being tested concerning key ecosystem functions: 1) elevated O3 decreases C, N and H2O cycling; 2) elevated CO2 increases C, N, and decreases H2O cycling; and 3) elevated CO2 eliminates regataive effects of O3 on C and N cycling and has an additive negative effect on H2O cycling. CO2 treatments are ambient and elevated (ambient +300 ppm). O3 treatments are high (hourly peaks to 160 ppb, SUM 06 ~ 10 ppm h-1 in 1999) and low (all values <40 ppb, SUM 06 = 0). After the first two seasons, there was increased shoot growth with elevated CO2, especially at the low O3 level. There were suggestions that CO2 and O3 affected other responses such as needle level gas exchange and soil microbial ecology. When completed, this study will provide detailed information as to the interactive effects of CO2 and O3 on biogeochemical cycling.