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ELEVATED CO2 AND TEMPERATURE ALTER THE RESPONSE OF PINUS PONDEROSA TO OZONE: A SIMULATION ANALYSIS
Tingey, D T., J A. Laurence, J. A. Weber, J. Greene, W E. Hogsett, S. Brown, AND E H. Lee. ELEVATED CO2 AND TEMPERATURE ALTER THE RESPONSE OF PINUS PONDEROSA TO OZONE: A SIMULATION ANALYSIS. ECOLOGICAL APPLICATIONS. Ecological Society of America, Ithaca, NY, 11(5):1412-1424, (2001).
Forests regulate numerous biogeochemical cycles, storing and cycling large quantities of carbon, water, and nutrients, however, there is concern how climate change, elevated CO2 and tropospheric O3 will affect these processes. We investigated the potential impact of O3 in combination with projected future climate and atmospheric CO2 concentrations on the annual biomass increment of Pinus ponderosa Doug. ex Laws, along a latitudinal gradient in California, Oregon, and Washington, USA, using TREGRO, a process-based whole-tree growth model. In our simulations, the annual biomass increment increased proportional to CO2 concentration; however, the magnitude varied among sites. Increasing air temperature (+1.3 C) increased growth at most sites. Elevated CO2 increased the temperature optimum for growth at four sites and decreased it at two sites. The annual biomass increment decreased with increasing O3 exposure. The differences in O3 sensitivity among sites were primarily controlled by differences in precipitation. The simulations indicated that increasing levels of tropospheric O3, changing climate and rising atmospheric CO2 can alter the C sequestrating potential of forests. Although increasing CO2 reduces O3 sensitivity, it does not eliminate the impact of O3; elevated CO2 would enhance C storage in forests more if O3 exposures were reduced, especially in the more polluted sites. The greatest benefit in C storage will come from reducing O3 exposures in the most polluted sites, however, we must also consider sites that have high inherent O3 sensitivity because of their mesic conditions. Limiting the increase of O3 levels in those areas will also increase C storage in forests. In contrast, C storage in other areas, that have a lower inherent O3 sensitivity would likely not be as impacted by increasing O3 exposures as the plants are climatically less sensitive to O3.
Record Details:Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LABORATORY
WESTERN ECOLOGY DIVISION