基于热消散原理的不同加热模式下油松树干液流特征

Characteristics of stem sap flow of Pinus tabulaeformis under different heating modes based on heat dissipation principle

为了验证间断加热模式对热消散树干液流测定的适应性,本试验选择油松为试验对象,采用热消散探针法测定树干液流,设置3种加热模式,分别为加热60 min×冷却0 min(60/0模式)、加热10 min×冷却50 min(10/50模式)、加热30 min×冷却30 min(30/30模式),以持续加热模式,即加热60 min×冷却0 min下测定结果为基准值,比较分析不同加热模式下油松树干液流的差异性特征。结果表明:3种加热模式下油松液流日变化规律一致,均呈现单峰型变化趋势;10/50和30/30模式下的最大温差均能在加热开始后迅速达到并相对稳定在最大温差状态,可有效测定树干液流;以60/0模式为参照进行线性拟合验证,10/50和30/30模式的斜率分别为0.5175、0.5051,经校正后误差分别为25.5%、3.1%,且30/30模式效果较好,校正方程为Fd=0.0241K1.256(R2=0.98)。可见,经校正后30/30间断加热模式下能够准确测定树干液流,且能缩短加热时间减少对树木的影响。

In order to verify the adaptability of intermittent heating mode to the measurement of heat dissipation sap flow,Pinus tabulaeformis was selected to measure the sap flow using heat dissipation probe method.Three heating modes were set up as 60 min heating/0 min cooling,10 min heating/50 min cooling and 30 min heating/30 min cooling.Comntinuous heating for 60 min was used as control.Differential analysis showed that the diurnal variation of Pinus tabulaeformis sap flow under the three heating modes was consistent with a single-peak variation trend.The maximum temperature difference of 10/50 and 30/30 modes appeared rapidly after heating and was relatively stable,which was friendly for effective measurement of sap flow.Taking 60/0 mode as the reference for linear fitting verification,the slopes of 10/50 and 30/30 modes were 0.5175 and 0.5051 respectively,and the corrected errors were 25.5%and 3.1%respectively.The effect of 30/30 mode was strongeer,and the correction equation was F_(d)=0.0241K^(1.256)(R^(2)=0.98).It can be seen that the corrected 30/30 intermittent heating mode can accurately measure the sap flow,and shorten the heating time to reduce the impact on trees.