NECC1013: Strategies to Evaluate and Mitigate Ozone Impacts on the Structure and Function of Vegetation
Statement of Issues and JustificationTropospheric ozone is a component of global climate change that is becoming critical to profitable production of agronomic and horticultural crops, efficient management of grazing lands, and appropriate stewardship of National Forests and Parks. Ozone is pervasive and the most damaging air pollutant in the US and the world, impacting the most productive US landscapes in the far West, Southeast, Northeast and Midwest (Booker et al., 2009). Twelve major crops and eight important trees are ozone-sensitive, with models indicating crop productivity losses up to five billion dollars, and forest and range losses in addition (Booker et al., 2009; Fishman et al., 2010; Krupa et al., 2001). Adverse effects of ozone on scenery and biodiversity in National Parks and Forests are also well documented (Kohut, 2007; U.S. EPA, 2006). There is recent evidence that ambient ozone may be damaging forests ecosystems by injuring understory vegetation, altering plant-herbivore relationships, and decreasing stream flow during drought periods (McLaughlin et al., 2007).
The biology of ozone impacts has been the focus of studies for many years (Bell and Treshow, 2002). However, existing knowledge of the mechanistic details of phytotoxicity and biochemical sites of attack are still insufficient to allow scaling from cell to organ to plant communities. As a result, efforts to predict ozone impacts and to utilize modern techniques of agronomy, horticulture, silviculture and plant breeding to mitigate them have been relatively unsuccessful. In addition, subtle effects of ozone on the nutritional quality of crops and grasslands can have profound effects on mammalian herbivore health and productivity (Krupa et al., 2004). New information will be required to address current agricultural practices in which new crop cultivars, many of which are genetically-modified, are being placed into production without specific consideration of their sensitivity to ambient ozone. Little is known about differential ozone effects on crops, weeds and invasive species (Booker et al., 2009), particularly with global increases in temperature and carbon dioxide. These issues are important to plant breeders, range managers, air quality regulators, ecosystem managers and climate modelers.
Customers and stakeholders for this information include the US EPA, National Park Service, Bureau of Land Management, USDA, US Forest Service, The National Arboretum, commodity groups such as the United Soybean Board and seed producers such as Monsanto Corporation, environmental groups, and various European and Asian environmental research organizations (for example, UNECE/ICP Vegetation, UNECE/ICP Forests, and IUFRO). In the past, stakeholders and clientele of Committee members have requested information to help them determine whether current and proposed National Ambient Air Quality Standards for ozone are appropriate. Producers have requested development of ozone-tolerant crops, forages and forest trees. Land managers have requested spatial and temporal projections of impacts of ozone and climate change on vegetated landscapes. Climate change modelers are concerned about interacting effects of ozone, atmospheric carbon dioxide and temperature on global C cycles.
No single institution or research group can evaluate ozone phytotoxicity at all relevant scales and in all informative biological systems. Linkages from molecular to ecosystem responses are critical and highly influenced by environmental and genetic factors. Current and previous Multi-State Research projects in this series have brought together a broad group of Experiment Station researchers with colleagues from USDA/ARS, non land-grant colleges and universities, and a number of foreign research universities and governmental agencies. Expertise spans the full range of plant biology, from genomics, through molecular biology, cellular and whole plant physiology, to community and landscape scale plant atmosphere exchange. A recent review by this group received an award as best review of the year by the publisher (Booker et al., 2009).
With the current proposal this effective group is moving from a research project to a coordinating and synthesis role. The continued multi-state effort is critical to further progress in activities of individual members, and to the review, synthesis and dissemination of available knowledge on management practices and tools related to ozone effects on vital US interests. The project will continue ongoing collaborations and further integrate the efforts of additional investigative groups. The technical outreach component of this committee has been especially important in transferring information to its members as well as to the general research community. The committee is especially valuable for younger scientists, since it provides an excellent opportunity for them to interact with experienced researchers from different areas of the country. A major strength of the group is the diversity of member research interests.
Applications of this work can: 1) improve ozone tolerance of crops and commercial trees through conventional breeding and molecular genetic technology; 2) better determine ozone effects on the structure, function and inter-species competition among plants including alterations in nutritive quality and impacts on genetically modified crops; 3) determine the combined effects of ozone with other growth regulating factors (e.g. elevated carbon dioxide and temperature) on crop and tree growth and productivity; and, 4) provide and evaluate indicators of ambient ozone impacts on plants that can be used to assess National Ambient Air Quality Standards and related Clean Air Act regulations.
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