【摘要】 通过对黑河上游排露沟流域海拔2 700m和2 900m处青海云杉森林生态系统不同季节的土壤水、植物水和大气水汽等不同水体稳定氧同位素组成(δ¹⁸O)的测定,运用Craig-Gordon模型、同位素稳态假设和Keeling Plot模型分别得出土壤蒸发、植物蒸腾和蒸散发的δ¹⁸O,结合多元线性混合模型将生态系统蒸散发分割为土壤蒸发和植物蒸腾。结果表明:土壤蒸发水汽的δ¹⁸O_E、植物蒸腾水汽的δ¹⁸O_T及蒸散发水汽的δ¹⁸O_ET分别介于-35.9‰～-25.2‰、-9.0‰～-4.2‰和-18.5‰～-10.2‰之间,三者顺序为δ¹⁸O_T>δ¹⁸O_ET>δ¹⁸O_E,满足同位素稳态假设。植物蒸腾对蒸散发的贡献率（f_T）在52.2%～88.4%之间变化,土壤蒸发对蒸散发的贡献率（f_E）在11.6%～47.8%之间变化,f_T远大于f_E,说明生态系统蒸散发大部分来自于植物蒸腾,即植物蒸腾是青海云杉森林生态系统蒸散发的重要组成部分。f_T与气温呈负相关,而与相对湿度呈正相关,说明气温对f_T起抑制作用,相对湿度对f_T起促进作用,但是相关系数不高,说明f_T在自然环境下还可能受除气温和相对湿度外的多种环境因素和生物因素综合影响,具体影响机理有待进一步探究。本研究结果可为进一步研究黑河流域区域内循环和流域尺度水循环研究提供理论依据。更多还原

【Abstract】 The stable oxygen isotope composition(δ¹⁸O)was measured in different water bodies such as soil water,plant water and atmospheric water vapor of Picea crassifolia forest ecosystem in the Pailugou catchment of upper reaches of the Heihe River at2 700m and2 900m altitude,respectively.The Craig-Gordon model,isotope steady state hypothesis and Keeling Plot model were used to obtain theδ¹⁸O of evaporation,transpiration and evapotranspiration,respectively.Combined the multiple linear mixed model to partition evapotranspiration into evaporation and transpiration.The results showed that:（1）Theδ¹⁸O_Eof evaporation,theδ¹⁸O_Tof transpiration and theδ¹⁸O_ETof evapotranspiration was between-35.9‰and-25.2‰,-9.0‰and-4.2‰,-18.5‰and-10.2‰,respectively.The order of them wasδ¹⁸O_T>δ¹⁸O_ET>δ¹⁸O_E,which according with the assumption of isotope steady state.（2）Contribution rate of evaporation to evapotranspiration（f_E）varied from11.6%to47.8%and contribution rate of transpiration to evapotranspiration（f_T）varied from52.3%to88.4%.f_Twas much larger than f_E,indicating that most evapotranspiration came from transpiration.Transpiration was a vital part of evapotranspiration in the Picea crassifolia forest ecosystem.（3）The f_Twas negatively correlated with air temperature but positively correlated with relative humidity,indicating air temperature restrained f_Tand relative humidity promoted f_Talthough the correlation was not significant.Addition,f_Twas also influenced by various environmental and biological factors except air temperature and relative humidity in natural environment.Temperature and relative humidity are not the only control factors of f_T.The results of this study can provide a theoretical basis for further studies on intra-regional circulation and watershed scale water circulation research in Heihe River basin.更多还原