This book focuses on the interactive effects of environmental stresses with plant and ecosystem functions, especially with respect to changes in the abundance of carbon dioxide. The interaction of stresses with elevated carbon dioxide are presented from the cellular through whole plant ecosystem level. The book carefully considers not only the responses of the above-ground portion of the plant, but also emphasizes the critical role of below-ground (rhizosphere) components (e.g., roots, microbes, soil) in determining the nature and magnitude of these interactions. Will rising CO2 alter the importance of environmental stress in natural and agricultural ecosystems? Will environmental stress on plants reduce their capacity to remove CO2 from the atmosphere? Are some stresses more important than others as we concern ourselves with global change? Can we develop predictive models useful for scientists and policy-makers? Where should future research efforts be focused?