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【目的】分析活立木内部含水率变化的影响因素,研究含水率在不同环境温度下的变化规律。【方法】在室外不同温度(-26"10℃)下采用时域反射计(time domain reflectometer,TDR)对落叶松和小叶杨两种活立木进行检测,获取树内温度和电磁波传播时间的连续变化值,据此推导出不同温度下活立木的含水率。在此基础上,分析了活立木内部电磁波传播时间和含水率的昼夜变化,以及较长时间周期内随温度变化的规律,确定了环境温度与含水率的定量关系,建立了两者之间的关系模型。【结果】在1个昼夜时间周期内,含水率和树内温度变化趋势基本一致,含水率变化略滞后一些,随昼夜平均温度的下降,含水率变化范围收窄;在较长时间周期内,随日均树内温度的降低,活立木样本平均电磁波传播时间和含水率均呈下降趋势,落叶松电磁波传播时间变化曲线没有明显拐点,含水率变化曲线在-6.3℃之前变化率较大(14.75%/℃),之后趋于平稳(0.94%/℃),小叶杨与之变化相似;树内温度和环境温度具有显著线性正相关性,二者线性模型拟合优度较高(R~2=0.91),可以用环境温度预测树内温度;树内温度与活立木含水率的关系分3个变化阶段,均呈线性关系,决定系数R~2均高于0.71。【结论】低温环境下,以环境温度为研究点探究活立木内部电磁波传播时间和含水率变化是可行的,通过相关公式可以推导出活立木内部含水率。
【Objective】 The influencing factors of moisture content in living wood were analyzed, and the variation of water content under different ambient temperature was studied. 【Method】 Two kinds of live larch trees, Larix gmelinii and Populus simonii, were detected at different temperatures (-26 ℃ and 10 ℃) by outdoor time-domain reflectometer (TDR), and the temperature and electromagnetic wave propagation time And then deduced the moisture content of living wood at different temperature.On the basis of this, the diurnal variation of electromagnetic wave propagation time and moisture content in living wood was analyzed, and the law of temperature change with time was determined The quantitative relationship between ambient temperature and water content was established and the relationship between them was established. 【Result】 The trend of water content and tree temperature was basically the same in one day and night time period, The average temperature of day and night decreased and the range of water cut narrowed. In a longer period of time, with the decrease of temperature in the tree, the average electromagnetic wave propagation time and moisture content of live wood samples showed a downward trend, the change of electromagnetic wave propagation time of larch There was no significant inflection point in the curve, and the change of water content curve was larger (14.75% / ℃) before -6.3 ℃ and then stabilized (0.94% / ℃) And the ambient temperature had a significant linear positive correlation, the goodness of fit of the linear model was higher (R ~ 2 = 0.91), and the temperature in the tree could be predicted by the ambient temperature. The relationship between the temperature in the tree and the water content of the live wood was divided into three The variation coefficient was linear with the coefficient of determination R ~ 2 higher than 0.71. 【Conclusion】 It is feasible to study the electromagnetic wave propagation time and moisture content in the living wood with the ambient temperature as the researching point under the low temperature environment. Derived live wood internal moisture content.