藏东南植物叶片水稳定氢氧同位素变化及其对气候与环境的响应

植物叶片水稳定氢氧同位素能够很好地反映植物生长周围的气候与生态环境信息。本项目拟以藏东南林芝地区从南到北四个野外站点为平台，在不同海拔高度上持续采集不同植物类型（木本针叶/阔叶、草本）的叶片样品，通过实验室真空低温蒸馏方法提取叶片水，测定叶片水稳定氢氧同位素，辅助并尝试开发适合青藏高原的叶片水稳态与非稳态等相关模型进行模拟，分析该区域叶片水稳定氢氧同位素时空变化特征，建立其对周边气象（温度、湿度、降水量等）、生态环境（气孔导度、蒸腾速率等）及海拔高度因子的响应模式及其现代过程的分馏模式，特别是其对不同大气环流系统（西风、局地环流和印度季风）的响应，这对于该区域树轮乃至其它植物载体（如叶蜡）的稳定氢氧同位素古气候记录的解译具有重要的指示意义。而且，了解叶片水及其它水体（土壤水、河水、降水等）稳定氢氧同位素，可以为进一步揭示局地水循环的过程与机制以及生态系统的蒸散发研究提供重要的数据基础。

Stable hydrogen and oxygen isotopes of leaf water in plants are powerful research tools to reflect the climate and eco-environmental conditions of the areas in which plants live. Based on four stations at the Nyingchi region in Southeastern Tibet, this project will focus on stable hydrogen and oxygen isotope variations in leaf water. We will collect samples from different species--woody (needle- and broad-leaf) and herbaceous plants at different altitudes, then extract water from leaves by the low-temperature vacuum distillation method, measure stable hydrogen and oxygen isotopic compositions of all samples, reveal the temporal and spatial distribution of stable hydrogen and oxygen isotopes in leaf water, and obtain the response model for climatic and eco-environmental information (such as air temperature, humidity, precipitation amount, stomatal conductance, transpiration rate, etc.) in the surrounding areas and elevation factor, especially its response to the westerlies, local moisture recycling and Indian monsoon, based on some leaf water models (such as the stable and non-stable models) which is suitable for the Tibetan Plateau. This work will provide insight into the interpretation of stable hydrogen and oxygen isotope records in tree rings and leaf wax in this study region. Moreover, understanding the stable isotope composition of leaf water and other water (soil water, river water and precipitation, etc.) is helpful to provide data set for the study of the local stable water isotope cycle, and the study of local evaporation and transpiration processes at the ecosystem scale.