科尔沁沙丘-草甸过渡带人工杨树林蒸腾耗水特征

采用热扩散茎流计和自动气象站对科尔沁沙丘-草甸过渡带人工杨树林的树干液流和环境因子进行长期连续监测。结果表明：不同天气条件下茎流速率差异明显，晴天各因子昼夜波动特征明显，雨天波动幅度小，阴天介于二者之间；不同天气类型影响茎流速率的主要气象因子不同，晴天茎流速率与净辐射相关性最高（偏相关系数为0.72），阴天与气温相关性最高（偏相关系数为0.69）；整个生长季典型晴天日平均茎流速率近似服从二次曲线，夏季大于春季和秋季，不同月份茎流速率日内变化差异显著，表现在峰值大小、液流启动时间和峰值出现时间不同；林地供水充足，持续干旱和雨后茎流速率没有显著差异，杨树蒸腾所需水分主要来自地下水，地下水位在09：00-17：00下降明显，且茎流速率越大下降幅度越大；不同胸径杨树茎流速率对各气象因子的时滞时间相同，而不同月份茎流速率对各气象因子的时滞时间不同。

Transpiration of Artificial Populus Forest in the Dunes-meadow Ecotone of Horqin Sandy Land

The thermal dissipation sap flow probe and the automatic weather station were applied to measure the sap flow of the artificial Populus and environmental factor for long-term in the dunes-meadow ecotone of Horqin Sandy Land. The results showed that the diurnal variation of sap flow velocity and meteorological factors varied significantly under different weather conditions, and each factor had obvious fluctuation characteristics of day and night in sunny days, and fluctuation extents were small in rainy days, and cloudy days were between the sunny day and rainy day; The main meteorological factors affecting the sap flow rate were different under different weather conditions, and the sap flow velocity was predominantly affected by net radiation in sunny days (partial correlation coefficient was 0.72), and affected by air temperature in cloudy days (partial correlation coefficient was 0.69); The average daily sap flow velocity of typical sunny day approximately obeyed quadratic curve in the whole growing season, and the summer was larger than the spring and the fall, and diurnal variation of sap flow velocity had significant differences in peak value, start time and peak time of sap flow in different months; Forest land had adequate water supply, and there were no significant differences in sap flow velocity after persistent drought and rain, and water required for transpiration of Populus was mainly from groundwater, and the groundwater table decreased significantly in 09:00-17:00, and the larger the sap flow velocity, the lower the groundwater table; For different diameter at breast height, the time lag of sap flow velocity to each meteorological factors was same, but for different months, the time lag of sap flow velocity to each meteorological factors varied obviously.