Application of tree-ring isotopic analyses to understand carbon and water exchanges in a tropical rainforest

本文分析了热带气候区树木木质部碳氧同位素组成。微气象观测和模式分析表明，木质部氧同位素值在一年中有两个高峰。木质部氧同位素的波动太分散，无法进行绝对定年。木质部放射性碳同位素的联合分析表明，树木氧同位素的变化与土壤含水量的变化规律相似。从碳同位素结果来看，随着土壤含水量的降低，树木的水分利用效率有增加的趋势。

We analysed carbon and oxygen isotope patterns of xylem of tree species from tropical climate, where trees do not have obvious tree-rings. Micro-meteorological observation and model analysis revealed that the value of the oxygen isotope of xylem would have two peaks in one year. Fluctuations of the oxygen isotope of xylem was too scattered for absolute dating. Combined analysis of the radioactive carbon isotope of xylem showed that the variations in the oxygen isotope of trees were similar to the pattern of the soil water content. From results of the carbon isotope, water use efficiency of the tree were tend to increase with decrease of the soil water content.