辽东栎不同方位边材液流季节动态及其对蒸腾耗水测算的影响

利用Granier树干液流测定系统,对黄土高原半干旱区天然辽东栎树干不同方位的边材液流动态进行了长期监测,并同步监测环境因子(空气温度、湿度、太阳辐射等),分析了不同方位液流通量密度的相互关系、对液流通量和蒸腾耗水量测算的影响以及与环境因子的关系。结果显示,辽东栎东、西、南、北4个方位测得的液流通量密度存在显著差异,并显著相关。辽东栎生长季内(5-10月)单株日蒸腾耗水量分别与日总太阳辐射和日均白天空气水气压亏缺进行指数饱和曲线拟合,拟合效果较好。采用2个方位和1个方位树干液流通量密度测算的整株蒸腾耗水量与采用4个方位的测算值分别相差约18%和30%,说明不同方位之间的液流差异可能成为蒸腾耗水测算的重要误差来源。

Seasonal Dynamics and Azimuthal Variations of Sap Flow in Quercus liaotungensis and Their Effects on Transpiration Estimates

The Granier-type thermal dissipation probes(TDP) were applied to a naturally-growing Quercus liaotungensis tree in the semiarid loess plateau region to measure the long-term dynamics and azimuthal variations of sap flow on xylem trunk.Air temperature,relative air humidity,and solar radiation were monitored at the same time.In this paper,the correlations among sap flux densities at four different azimuthal directions,effects of different data source on the estimates of whole-tree sap flow and transpiration,a...