Research Program Area: Ecosystem & Multimedia Effects
Recent declines in growth and vigor, as well as elevated mortality of forest trees in California have generated increased concern that these changes have been caused by air pollution. The current consensus of the forest-science community is that ozone and other oxidants are Influencing the structure and productivity of forest ecosystems In California and in other regions of the United States. The magnitude of ozone effects on tree species and forest ecosystems, however, is not known; nor have the exposures producing such effects been adequately characterized.
This study was designed to estimate risks to California forests and forest resources due to ambient ozone concentrations and to develop a data base of forest resources for use in future Air Resources Board analyses. To accomplish these objectives, three principal research tasks were performed:
1. Construct a data base of forested resources in California* This data base contains 91 variables describing forest resources in 3500 forest grid cells. Bach grid cell covers approximately 30,000 acres. Data on forest tree species volume, ownership, elevation, soil type, watershed, recreation, and aodeled ozone concentrations are included in the data base.
2. Evaluate the sensitivity of California forest tree species to ozone. While ozone caused forest Injury has been widely described in California, the complexity of this injury has prevented a quantitative characterization of forest tree / ecosystem response to elevated ozone concentrations. This task developed ozone sensitivity rankings for California forest tree species based on available literature and the expert judgment of Dr. Joseph McBride of the University of California at Berkeley and Dr. Paul Hiller of the USDA Forest Service and the University of California at Riverside.
3. Perform risk assessment using data contained in the data base and sensitivity rankings established in Task 2, this task evaluated the ozone caused risk to forest resources in California. These results are sumarized across the state, by ownership category, watershed, county, air basin and national forest.
For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753
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