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OZONE AMBIENT AIR QUALITY STANDARD HAS BENEFICIAL EFFECT ON PONDEROSA PINE IN CALIFORNIA
Citation:
Tingey, D T., J. A. Laurence, W E. Hogsett, AND E H. Lee. OZONE AMBIENT AIR QUALITY STANDARD HAS BENEFICIAL EFFECT ON PONDEROSA PINE IN CALIFORNIA. ENVIRONMENTAL MANAGEMENT. Springer-Verlag, New York, NY, 34(3):397-405, (2004).
Description:
Ambient air quality standards and control strategies are implemented to protect humans and vegetation from adverse effects. However, to date there has not been a simple and objective method to determine if the standards and resultant control strategies have reduced O3 impacts on vegetation. We have developed a process-based the TREGRO tree-growth model to show that over the past 37 years changes in O3 exposure, with accompanying variation in climate, are reflected in changes in the growth of Pinus ponderosa in the San Bernardino mountains near Los Angeles, California USA. The model provides a framework for analyzing O3 effects on tree growth over several decades. Despite variation in temperature and precipitation over the study period, increasing O3 exposure reduced tree growth (1979 maximum O3 exposure and tree growth reduction) whereas decreasing O3 exposures during the 1980s and 1990s allowed tree growth to increase. The pattern implies that emission control strategies taken to reduce O3 exposures benefited P. ponderosa growth in the San Bernardino mountains. This modeling approach provides a powerful tool for solving the difficult problem of evaluating regulatory effectiveness by simulating plant response using long-term climate and air pollution exposure records.