不同时间尺度北京蟒山油松树干液流对环境因子的响应

探究不同时间尺度蒸腾与环境因子的关系并明确其主控因子，对于理解蒸腾对环境响应规律和驱动机制具有重要的理论意义。以北京蟒山国家森林公园的油松为例，开展树干液流及气象指标、土壤温湿度等环境因子的长期定位观测，并分析不同时间尺度油松液流速率与环境因子的关系。研究结果表明，在日尺度上，土壤温度、大气相对湿度、土壤湿度与液流速率呈极显著正相关，这3个因子对液流速率变化的贡献量分别占28.3%、11.7%和10.1%;在月尺度上，土壤温度对液流速率的影响最大，贡献量占比49.7%,土壤湿度和相对湿度的贡献量分别为7.3%和6.4%;在年尺度上，相对湿度对液流速率的年际变化的贡献量高达93.3%,是关键控制因子。随着时间尺度的扩展，环境因子对油松液流速率的控制作用逐渐增强。本研究的结果可以为植物蒸腾的时间尺度转换、未来全球气候变化背景下植物蒸腾耗水特征的预测提供理论依据。

Relationships between sapflux density of Pinustabuliformis trees and environmental factors at different temporal scales in Mangshan National Forest Park of Beijing, China

Investigating the relationships between sapflux density and environmental factors and clarifying the determining factors are crucial for deeply understanding mechanism of environmental controls on transpiration. In this study, sapflux density (Js) of Pinustabuliformis trees,meteorological variables, soil moisture (SMandsoil temperature (Ts)were continuously monitored in Mangshan National Forest Park in the Northwest Beijing, China. The results showed that the factors that mainly affectsJs were varied at different temporal scales. At daily scale,Ts, relative humidity (RH), SM were positively significantly correlated with Js. The relative contributions of Ts, RH and SM were 28.3%, 11.7% and 10.1%. At monthly scale, Ts was also the dominant factor that determine Js and its contribution was 49.7%. The contributions of SM and RH were 7.3% and 6.4%, respectively. At annual scale, RH dominated the temporal variations in Js and its contribution was 93.3%. The results also showed that the controls of environmental factors on Js increased with temporal scaling from short time (day) to longer (month and year).This study would provide basic knowledge on temporal scale transformation of plant transpiration and predication of plant water consumption in the context of climate change.