青藏高原(东北部)现代植物碳同位素组成特征及其气候信息

分析了青藏高原(东北部)现代植物(全部为C3植物)全木混合样的碳同位素组成(其δ13C值分布范围一般为-235‰~-308‰,平均值为-266‰),对影响其变化的各种环境因素进行了探讨.研究表明,降雨量及大气压力是影响该区植物δ13C值变化的最重要环境因素.一方面,降雨量增大,空气相对湿度增大,植物的δ13C值降低(偏负);另一方面,大气压力降低,植物的δ13C值增大(偏正).可见,植物中保存着自然环境变化的大量信息.

青藏高原(东北部)现代植物碳同位素组成特征及其气候信息

Global change become a world wide concerned problem in the recent years. The study of plant carbon isotopic composition become an important field in the research of global change,in which a fundamental goal is to determine the contro ling factors of plant carbon isotope discrimination and composition. The paper gives an analysis on the carbon isotope composition of modern plants ( all are C₃ species) in Qinghai-Tibet plateau(NE)and a detailed discussion on t he various factors that can influence it. The value of δ13C of 61 samples varies from -23.5‰ to -30.8‰，with an average of -26.6‰. Analysis shows that with the same plant the δ13C value increases with the increase of altitu de and decresases with the increase of latitude.The result of this study shows t hat precipitation,air moisture and pressure are the most important environmental factors to the change of δ13C. The less the amount of precipitation, the more positive the plant δ13C values are. On the other hand,the higher th e air pressure the more negative the δ13C values are. It is now clear tha t plant δ13C value relates directly to the assimilation of leaf to CO₂( A),leaf stomatic conductance(g) and intercellular/ambient partial pressure ratio (Pi/Pa). A(cording to) their effect on A, g and Pi/Pa,it is clear that the precipitation, air moisture and pressure cause the change of plant δ13C value. The study suggests that a lot of information reflecting the change of nature env ironmental can be recorded in plants.So it is completely possible to extract cli matic information from plant δ13C.