Grantee Research Project Results
Final Report: Modeling Ozone Flux to Forests Across an Ozone Concentration Gradient in the Sierra Nevada Mountains, CA.
EPA Grant Number: R826601Title: Modeling Ozone Flux to Forests Across an Ozone Concentration Gradient in the Sierra Nevada Mountains, CA.
Investigators: Goldstein, Allen H. , Panek, Jeanne A.
Institution: University of California - Berkeley
EPA Project Officer: Chung, Serena
Project Period: August 1, 1998 through October 31, 2002
Project Amount: $621,367
RFA: Ecological Indicators (1998) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems , Ecological Indicators/Assessment/Restoration
Objective:
The objectives of this research project were to: (1) contribute to the efficacy of forest health monitoring; and (2) enhance the general understanding of the relationship between ozone exposure and forest response in California ponderosa pine ecosystems. Tropospheric ozone is a pollutant responsible for forest damage worldwide. There is a developing effort in the United States and Europe to replace current metrics of vegetation ozone exposure with metrics that reflect the more biologically meaningful ozone taken up by foliage. This requires measuring and modeling ozone uptake across a wide variety of climates and ozone deposition regimes. There is a paucity of models describing physiology of forests (needed to estimate ozone uptake, since ozone uptake is equivalent to ozone concentration multiplied by the stomatal conductance to ozone) in seasonally drought-stressed forests, such as those in California. Therefore, we measured ozone uptake, both directly (through eddy covariance methods) and indirectly (from direct measures of leaf-level stomatal conductance), to ponderosa pine forests in the Sierra Nevada, CA, and developed a model to estimate ozone uptake. We also developed a method for using δ13C as a proxy for stomatal conductance to estimate ozone uptake.
Summary/Accomplishments (Outputs/Outcomes):
Our research has produced several critical breakthroughs in understanding the interactions between ozone and sensitive pine species, including:
· Ozone concentration exposure metrics do a poor job of representing the actual amount of ozone entering and, therefore, damaging the foliage of trees. A better metric for seasonally drought-stressed forests would incorporate forest physiological activity as a control over ozone uptake by vegetation (Panek, et al., 2002).
· Only one third of total annual ozone deposition occurs in summer, when ozone concentrations are highest, suggesting that deposition at other times of the year could be important in causing ozone damage (Kurpius, et al., 2002).
· Interannual differences in ozone deposition mainly are controlled by the moisture content and the phenology of the ecosystem. Higher ozone deposition velocity coincided with higher soil moisture and lower vapor pressure deficit. Early budbreak caused a significant increase in cumulative ecosystem ozone uptake, and the highest ozone deposition velocity occurred 3-4 weeks after budbreak each year. These results imply that changing climatic patterns could have a large impact on ozone uptake by ecosystems (Bauer, et al., 2000).
· Stable carbon isotopes in starch of ponderosa pine needles are a moderately good indicator of short-term dynamics of stomatal conductance.
· Ponderosa pine trees respond to increased soil water availability during a typical summer drought by increasing stomatal conductance and thus increasing ozone and CO2 uptake (Panek and Goldstein, 2001).
· Typical summer drought protects pine trees in the Sierra Nevada from taking up ozone at peak ozone concentrations during normal climate years by causing stomatal constraint. But in wet years (i.e., El Niño years) ozone uptake can substantially be enhanced. Predicted changes in climate, particularly those affecting water availability, certainly will affect ozone uptake in Sierra Nevada ponderosa pine trees. Uptake also varies spatially in the Sierra Nevada. Ozone uptake is highest in the southern Sierra Nevada, where ozone concentrations generally are higher.
Journal Articles on this Report : 7 Displayed | Download in RIS Format
| Other project views: | All 19 publications | 10 publications in selected types | All 8 journal articles |
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Bauer MR, Hultman NE, Panek JA, Goldstein AH. Ozone deposition to a ponderosa pine plantation in the Sierra Nevada Mountains (CA): a comparison of two different climatic years. Journal of Geophysical Research 2000;105(D17):22,123-22,136. |
R826601 (2000) R826601 (Final) |
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Goldstein AH, Hultman NE, Fracheboud JM, Bauer MR, Panek JA, Xu M, Qi Y, Guenther AB, Baugh W. Effects of climate variability on the carbon dioxide, water, and sensible heat fluxes above a ponderosa pine plantation in the Sierra Nevada (CA). Agricultural and Forest Meteorology 2000;101(2-3):113-129. |
R826601 (1999) R826601 (2000) R826601 (Final) |
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Kurpius MR, McKay M, Goldstein AH. Annual ozone deposition to a Sierra Nevada ponderosa pine plantation. Atmospheric Environment 2002;36(28):4503-4515. |
R826601 (2001) R826601 (Final) |
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Kurpius MR, Panek JA, Nikolov NT, McKay M, Goldstein AH. Partitioning of water flux in a Sierra Nevada ponderosa pine plantation. Agricultural and Forest Meteorology 2003;117(3-4):173-192. |
R826601 (2001) R826601 (Final) |
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Law BE, Goldstein AH, Anthoni PM, Unsworth MH, Panek JA, Bauer MR, Fracheboud JM, Hultman N. Carbon dioxide and water vapor exchange by young and old ponderosa pine ecosystems during a dry summer. Tree Physiology 2001;21(5):299-308. |
R826601 (Final) |
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Panek JA, Goldstein AH. Response of stomatal conductance to drought in ponderosa pine: implications for carbon and ozone uptake. Tree Physiology 2001;21(5):337-344. |
R826601 (1999) R826601 (2000) R826601 (2001) R826601 (Final) |
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Panek JA, Kurpius MR, Goldstein AH. An evaluation of ozone exposure metrics for a seasonally drought-stressed ponderosa pine ecosystem. Environmental Pollution 2002;117(1):93-100. |
R826601 (2001) R826601 (Final) |
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Supplemental Keywords:
forest ozone damage, modeling forest response, carbon isotopes, forest physiological processes, carbon cycling, water cycling, ozone deposition, pollution stress, air, ecosystem protection/environmental exposure and risk, geographic area, RFA, chemical mixtures, ecological effects, human health, ecological indicators, ecology, ecosystem protection, ecosystem/assessment/indicators, environmental chemistry, forestry, state, exploratory research, environmental biology, tropospheric ozone, California, CA, Sierra Nevada Mountains, atmospheric contaminants, carbon storage, ecosystem indicators, forest ecosystems, forests, meteorological fluctuations, meteorology, ozone, ozone flux, pine trees., RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Air, Geographic Area, Ecological Indicators, State, Ecosystem Protection, Forestry, Ecology, Environmental Chemistry, Ecosystem/Assessment/Indicators, tropospheric ozone, Ecological Effects - Environmental Exposure & Risk, California (CA), pine trees, stressors, carbon storage, meteorological fluctuations, forests, ecosystem indicators, Sierra Nevada Mountains, atmospheric contaminants, meteorology, ozone, ozone fluxProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.