毛乌素沙地杨柴液流变化对气象因子的响应

采用FLOW32-1K (Thermal Dissipation Probe)热平衡包裹式液流仪对毛乌素沙地杨柴(Hedysarum leave)植株液流速率进行了连续监测，同步监测灌木林地内气温、太阳辐射、相对湿度和饱和水汽压差(VPD)等气象因子，探讨了在不同时间尺度下杨柴植株液流特征及其与气象因子的关系。结果表明：(1)不同径级(3—4 mm、4—6 mm和>6 mm)杨柴植株的日平均液流速率分别为5.61 g/h、9.29 g/h、35.30 g/h,平均日液流量分别为(134.72±82.48)g/d、(223.06±152.20)g/d、(847.23±403.38)g/d。不同天气条件下的树干液流速率晴天>阴天，液流速率变化呈“昼高夜低”,不同月份表现为8月>7月>9月。(2)影响晴天和雨天杨柴植株液流的首要气象因子都是太阳辐射，小时尺度下，太阳辐射、气温、相对湿度和饱和水汽压共同解释杨柴液流的75%以上，在日尺度下，气象因子可以共同解释其80.8%以上；且随着时间尺度增大，进入回归方程的气象因子个数呈减小趋势，但气象因子对杨柴液流变化的解释度呈增...

Responses of sap flow of Hedysarum leave to climatic factors in Mu Us Sandy land

The FLOW32-1K wrapped heat balance sap flow meter was used to conduct long-term continuous observation on the sap flow velocity of Hedysarum leave in the Mu Us Sand land. In addition, the meteorological factors including air temperature (T), solar radiation (R), relative humidity (RH), vapor pressure deficit (VPD), and the characteristics of H. leave sap flow were investigated. The correlations between environmental factors and different temporal scales were determined. The findings revealed the following:(1) the average daily sap flow rates of different diameter classes (3-4 mm, 4-6 mm, and >6 mm) were 5.61 g/h, 9.29 g/h, and 35.30 g/h, respectively. The average daily sap flow was (134.72±82.48) g/d, (223.06±152.20) g/d, and (847.23±403.38) g/d, respectively. Under different weather conditions, the sap flow rate was higher in sunny days than that in rain days, and the change of sap flow rate was higher in day and lower in night, with different months being August > July > September. (2) Solar radiation was the main meteorological factor affecting plant sap flow in different days. At the hourly scale, solar radiation, temperature, relative humidity and saturated vapor pressure could explain more than 75% of sap flow, whiel at the daily scale, the meteorological factors could explain more than 80.8% of sap flow. With the increase of time scale, the number of meteorological factors entering the regression equation decreased, but the explanatory degree to the change of sap flow of H. leave increased. In this study, the change of H. leave sap flow was estimated by meteorological factors and prediction model under the condition that continuous observation could not be carried out in the future, so as to guide vegetation restoration and water resource management in Mu us Sandy land.