Synergistic Effects of Elevated CO2 and 03 on Stomatal Conductance and Photosynthetic Pathway

co2和03对植物的生长、生理生化都有深远的影响。鉴于每种气体的含量都在增加并将继续增加，这可能对自然和农业生态系统中植物的功能和生产力造成重大影响。研究了co2和03浓度升高对中西部森林和草原6种多年生林冠优势群落的交互作用。研究物种的内在特征不同，这可能导致它们对大气污染物的反应不同。不同树种在气孔导度和光合途径上存在差异。研究人员将检验一个假设，即二氧化碳浓度的升高将部分改善03的有害影响。他们还将测试一些其他关于生长形式、气孔导度和光合途径对污染物反应的假设。总的来说，在所有物种中，如果03和co2之间存在显著的相互作用，而不是严格的加性联合响应，这表明，大气中这两种气体浓度的持续升高对植物生理行为的影响可能非常复杂，难以预测或监测。这项研究的结果将对我们了解某些生理“生活史”特征与不断变化的大气环境之间的关系具有重要意义。此外，它们应该有助于我们的国家政策和研究重点的集中，通过增加小但不断增长的数据库来解决自然系统对快速变化的大气成分的反应。

Both C02 and 03 have profound effects on plant growth, physiology and biochemistry. Given that levels of each gas are increasing and will continue to increase, this may result in substantial impact on the function and productivity of plants in natural and agroecosystems. Research is proposed on the interactive effects of elevated levels of both C02 and 03 on six perennial canopy dominants of the forests and prairies of the Midwest. The study species differ in intrinsic characteristics that may result in differing response to atmospheric pollutants. The species differ in growth form stomatal conductance and photosynthetic pathway. The investigators will test the hypothesis that elevated levels of C02 will partially ameliorate the deleterious effects of 03. They will also test a number of other hypotheses relating growth form, stomatal conductance and photosynthetic pathway to pollutant response. In general, among all species, if there are significant interactions between 03 and C02, rather than a strictly additive combined response, this will suggest that the impacts of continued elevation of the atmospheric concentrations of these two gases on plant physiological behavior may be exceedingly complex and difficult to either predict or monitor. The results of this research will be important to our basic understanding of the relationships of certain physiological "life history" traits to a changing atmospheric environment. In addition, they should help focus our national policy and research priorities by adding to the small but growing data base addressing the response of natural systems to a rapidly shifting atmospheric composition.