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Ozone Effects Studies


Monitoring ozone and tree response in Sequoia/Kings Canyon National Park, CA
Ozone affects human health, causing respiratory problems, and vegetation, causing visible foliar injury and reducing growth and reproduction. The National Park Service monitors ozone in certain parks and is conducting studies on vegetation to assess and better understand the effects of ozone. Vegetation injury from ozone has been documented in a number of parks, including Great Smoky Mountains, Shenandoah, Sequoia, Yosemite, and Rocky Mountain National Parks. Recent studies from Great Smoky Mountains National Park found that tree growth was reduced 30-50% in high ozone years. In addition, ozone increased water loss from trees, reducing soil moisture and streamflow in the forest. Ozone also reduces photosynthesis in plants, reducing their ability to store, or sequester, carbon.

National Ozone Risk Assessment

This project has developed ozone injury risk assessments for the 270 parks in the Inventory and Monitoring program. The assessment will help staff from each of the parks with significant natural resources to determine whether ozone injury surveys should be conducted. The project is also developing guidance for assessing ozone injury on trees and plants in the field. This project was initiated in the fall of 2003 with Dr. Robert Kohut of Boyce Thompson Institute. The assessments were completed in 2005.

Remote Sensing of Ozone Uptake in Ponderosa and Jeffrey Pine Forests in Sequoia, Kings Canyon, and Yosemite National Parks

Ozone injury in ponderosa and Jeffrey pines can occur when ozone is taken up through open pores (stomates) in the leaves. The amount of available soil moisture may determine the duration of stomate opening, which in turn may influence how much ozone a tree receives. Sequoia, Kings Canyon and Yosemite all receive high ozone concentrations, and previous studies have documented considerable ozone injury to pines in these parks. This project used a combination of remote sensing of tree condition, and field measurements of ozone concentration, tree condition and soil moisture to assess the value of large-scale predictive techniques for determining which forest stands will be at high risk for ozone injury. The project began in 2002 and was completed in 2004. Dr. Jeanne Panek was the lead researcher on the project. The final report was completed in 2005.

Ozone Pollution Damage to Growth and Physiology of Native Trees and Wildflowers in Great Smoky Mountains National Park

Great Smoky Mountains National Park receives some of the highest amounts of ozone pollution in the country. This project was initiated in 2002 to better understand the mechanisms by which ozone pollution in the park affects native vegetation. Monitoring of trees in the park in 2002 showed large diameter growth reductions that correspond to sharp increases in summer ozone concentrations. The project also involves monitoring coneflowers for growth changes and ozone injury. An ozone biomonitoring garden was established at Purchase Knob in 2002. Park personnel are using the biomonitoring garden as a teaching tool for student volunteers, educational events, training sessions, and teacher and student workshops. Principal Investigators for this project are Dr. Art Chapelka from Auburn University and Dr. Howie Neufeld from Appalachian State University. The final report was completed in 2005.

Grulke NE, Neufeld HS, Davison AW, Roberts M, Chappelka AH. 2007. Stomatal behavior of ozone-sensitive and insensitive coneflowers (Rudbeckia laciniata var. digitata) in Great Smoky Mountains National Park. New Phytologist 173: 100–109.

Neufeld HS, Chappelka AH, Somers GL, Burkey KO, Davison AW, Finkelstein PL. 2006. Visible foliar injury caused by ozone alters the relationship between SPAD meter readings and chlorophyll concentrations in cutleaf coneflower. Photosynthesis Research 87: 281–286.

Burkey KO, Neufeld HS, Souza L, Chappelka AH, Davison AW. 2006. Seasonal profiles of leaf ascorbic acid content and redox state in ozone-sensitive wildflowers. Environmental Pollution 143: 427–434.

Davison AW, Neufeld HS, Chappelka AH, Wolff K, Finkelstein PL. 2006. Interpreting spatial variation in ozone symptoms shown by cutleaf cone flower, Rudbeckia laciniata L. Environmental Pollution 125: 61–70.

Souza L, Neufeld HS, Chappelka AH, Burkey KO, Davison AW. 2006. Seasonal development of ozone-induced foliar injury on tall milkweed (Asclepias exaltata) in Great Smoky Mountains National Park. Environmental Pollution 141: 175–183.

The Effects of Ozone and Climate on Tree Growth, Water Use, Soil Moisture Content, and Streamflow in Great Smoky Mountains National Park

Seasonal patterns of stem growth and sap flow velocity were examined in mature trees from a mixed deciduous forest in Great Smoky Mountains NP to evaluate the effects of variations in ambient ozone exposure and climate on patterns of stem growth and water use. Ambient ozone caused a periodic slowdown in seasonal growth patterns that led to seasonal losses in stem growth of 30–50% for most species in a high ozone year. Researchers also documented depletion of soil moisture in the rooting zone and reduced late-season streamflow in forested watersheds during the high ozone year, findings that suggest that ozone will amplify the adverse effects of increasing temperatures on forest growth and forest hydrology. The Principal Investigator for this project was Dr. Sandy McLaughlin from the University of Tennessee.

McLaughlin SB, Nosal M, Wullschleger SD, Sun G. 2007. Interactive effects of ozone and climate on tree growth and water use in a southern Appalachian forest in the USA. New Phytologist 174: 109–124.

McLaughlin SB, Wullschleger SD, Sun G, Nosal M. 2007. Interactive effects of ozone and climate on water use, soil moisture content and streamflow in a southern Appalachian forest in the USA. New Phytologist 174: 125–136.

Ozone Injury Survey at Rocky Mountain National Park

In 2006, a survey was conducted to evaluate the incidence and severity of foliar ozone injury at Rocky Mountain NP. The survey was intended to field test the "Handbook for Assessment of Foliar Injury on Vegetation in the National Parks (432 kb)" by Dr. Robert Kohut of the Boyce Thompson Institute at Cornell University, and to also establish an ozone biomonitoring program at the park. Several species were examined for injury, including aspen, dogbane, and cutleaf coneflower. No injury was observed on the aspen and dogbane. In contrast, about 20 percent of the coneflower examined had visible ozone injury. The difference in response may be due to the fact that the aspen and dogbane were growing in dry areas; dry conditions may preclude ozone uptake because of stomatal closure to prevent water loss. The coneflowers, on the other hand, were growing in moister areas. Adequately watered plants tend to have their stomates open during the day, allowing ozone to enter the plant and induce injury. A project summary for the 2006 survey was completed in 2007.

Coneflowers were again examined in the park in 2007 and injury was again observed.

updated on 10/09/2007  I   http://nature.nps.gov/air/studies/ecoOzone.cfm   I  Email: Webmaster