This 33-chapter volume presents a critical examination of the importance of stable isotopes in understanding key plant metabolic processes. - Carbon isotope analyses for estimates of plant water use and metabolism - Integrated estimates of stress impacts and life history in ecological systems - Hydrogen and oxygen isotope analyses for evaluating water sources and transpiration - Use of stable isotopes in scaling from leaf to global levels - Sections include: History and Theoretical Considerations, Ecological Aspects of Carbon Isotope Variation, Agricultural Aspects of Carbon Isotope Variation, Genetics and Isotopic Variation, Water Relations and Isotopic Composition