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2009年4月14日—10月10日,利用热扩散式液流探针(thermal dissipation probe,TDP)对延安市燕沟流域刺槐生长期树干边材液流进行连续监测,并同步监测光合有效辐射、气温、空气相对湿度、风速和降雨量等气象因子.结果表明:刺槐树干液流流速日变化呈单峰曲线,且不同季节液流的日动态变化存在明显差异.叶芽期(4月)液流启动时间在12:00左右,液流达到峰值的时间为18:00左右;5—8月液流启动时间提前到5:30—7:30,液流达到峰值的时间提前至15:00左右;9月以后,液流启动时间在8:00左右,液流达到峰值的时间提前至11:30—13:00.树干液流流速月平均值总体上呈“低-高-低”趋势,其中,4月的平均液流流速最小,为0.000549cm.s-1,8月最大,为0.002610cm.s-1.树干液流速率与气象因子密切相关,其相关性程度依次为:温度>水汽压亏缺>光合辐射强度>相对湿度>风速,且可用光合辐射强度和水汽压亏缺线性表达式来估测,其多元线性回归模型达到极显著水平(P<0.001).
From April 14 to October 10, 2009, thermal diffusive thermal dissipation probe (TDP) was used to monitor the flow of trunk sapwood in the growth period of Robinia pseudoacacia in Yan’an Yan’an catchment. Simultaneous monitoring of photosynthetic efficiency The results showed that: the diurnal variation of flow velocity of acacia locust showed a single peak curve, and the diurnal variation of the flow in different seasons was significantly different. The leaf bud period (April) Flow start time at 12:00 or so, the flow peak time is about 18:00; 5-8 month flow start time ahead of time 5: 30-7: 30, the peak flow time to advance to 15: 00; after September, the start-up time of the liquid flow is around 8:00, and the flow peak time is advanced to 11: 30-13: 00. The monthly average of the flow velocity of the sap flow is generally “low-high-low ”Trend, in which the average flow velocity in April is the smallest, 0.000549cm.s-1, the highest in August, 0.002610cm.s-1. The sap flow rate and weather factors are closely related to the degree of relevance in turn As follows: temperature> vapor pressure deficit> photosynthetic radiation intensity> relative humidity> wind speed, and available photosynthetic radiation intensity and vapor pressure deficit line Expression to estimate that multiple linear regression model was extremely significant (P <0.001).