Application of stable isotope technique in the study of plant water use
稳定同位素技术在植物水分利用研究中的应用

It has seen an increasing number of studies in plant ecological research using stable isotope techniques during the past two decades. Applications and advances of stable isotopes of carbon, hydrogen and oxygen in plant-water relations have been briefly summarized. Studies on hydrogen and oxygen stable isotope ratios of xylem water in plants provide new information on plant water sources, competition for water among different functional types, hydraulic lift by deep root plants, and rainwater use patterns by plants under natural conditions. Analyses of hydrogen and oxygen isotopes in tree rings have the potential to detect long-term patterns of plant water use. Stable carbon isotope discrimination provides a useful measure of integrated carbon-water balance in plants, and is generally correlated with plant water use efficiency. Carbon isotope discrimination changes with habitats, showing an increase from cool moist to hot dry conditions. Carbon isotope values in different plant tissues/organs can be used to examine plant water use strategies across different temporal scales. Recently, the isotopic values of leaf water, water vapor from leaf surfaces, atmospheric water vapor, and the sources of water taken up by plants have been used to estimate the proportions of plant transpiration and evaporation in water vapor efflux from an ecosystem. Stable isotope techniques play a critical role in tracing the movement of water along the soil-plant-atmosphere continuum.