Xiahong Feng - Current Research Interests

• Effect of Sea Ice on Arctic Precipitation
• Hydrogen and oxygen isotope studies of tree rings
• Oxygen and hydrogen isotopic compositions in leaf water
• Study of plants’ water used efficiency using C isotopes of tree rings
• Carbon and nitrogen cycles in plant-soil systems
• Isotope hydrology and hydrochemistry

Study of plants’ water used efficiency using C isotopes of tree rings

Desert tree.

Carbon isotopes in tree rings record the isotopic composition of the atmosphere and, under certain conditions, the atmospheric CO 2 concentrations. Using carbon isotopes of tree rings we can examine whether natural trees have experienced any physiological changes as a result of increasing atmospheric CO 2 concentration. One physiological character of plants that are important for the global water cycles and carbon cycle, and can be quantified by carbon isotopes is plants’ water use efficiency, which is defined as the mass water transpired per unit mass carbon fixed by photosynthesis. I have shown that many natural trees increase their water use efficiency with an increasing atmospheric CO 2 concentration. This research may be linked with that of C and N dynamics in plant-soil systems (see Carbon and nitrogen cycles in plant-soil systems). We hope to quantify changes of both water and nutrient use efficiency as a function of space (under different climate) and time.