半干旱黄土区山毛桃树干液流变化特征及其与环境因子的相关分析

Characteristics of Sap Flow and Correlation Analysis With Environmental Factors of Prunus davidiana in Semiarid Loess Area

以半干旱黄土区山毛桃为研究对象,开展树干液流和气象指标、土壤水分含量等环境因子监测,分析在不同时间尺度下液流速率与环境因子的相关性差异,确定主要影响因子,对于理解植物蒸腾对环境的响应机制和时间尺度转化具有重要的意义。结果表明,山毛桃液流速率呈明显的昼高夜低的变化规律,且在非降雨天主要受100 cm以下深层土壤水分影响,降雨过后则主要与100 cm和120 cm深度的土壤水分有关;在月尺度下,饱和水汽压差对于液流速率变化的贡献量达90.2%,是关键控制因子;在日尺度下,太阳辐射对液流速率的影响最大,其次是空气温度,贡献量所占比例分别为58.1%和14.4%;在小时尺度下,对5、6月液流速率的影响最大的环境因子是空气温度,7、8月是太阳辐射,而9月则是饱和水汽压差。研究认为,随着时间尺度的扩展,环境因子对山毛桃液流速率的控制影响愈加强烈。

Taking Prunus davidiana occurring in semiarid loess area as the research object,the tree sap flow and environmental factors were simultaneously monitored,such as meteorological indices and soil moisture.The relationship between the sap flow velocity and environmental factors at different time scales were analyzed.The key factors were determined.The significance of this study was to understand the response mechanism of plant transpiration to environment and time scale conversion.The results showed that the sap flow was generally high in the daytime and low at night.At monthly scale,the vapor pressure deficit dominated the temporal variations in sap flow and its contribution was 90.2%.At daily scale,the dominant factor was solar radiation,followed by temperature,the contribution rates were 58.1%and 14.4%,respectively.At hourly scale,air temperature was the dominant factor that determined sap flow in May and June,solar radiation was the dominant factor in July and August,and vapor pressure deficit was the dominant factor in September.The study suggests that with the expansion of time scale,the influence intensity of environmental factors on sap flow becomes more and more extensive.