基于阻抗仪和ERT技术的红松内部腐朽定量检测

Quantitative characterization of decay detection in standing trees of Korean pine based on Resistograph and ERT

为了定量表征红松活立木内部腐朽情况,在黑龙江省五营国家森林公园选取了15棵有不同腐朽程度的红松,应用Resistograph树木微钻阻抗仪和Pi CUS Treetronic树木电阻断层成像仪得到南北向与东西向的微钻阻力变化和同样高度上的截面电阻率分布图,对比分析阻抗仪测量方向上的电阻率变化和微钻阻力变化。用树木生长锥在样木的测量位置附近各取南北向与东西向的木芯,将其带回实验室测量质量损失率。将微钻阻力的下降幅度定义为阻力损失,对阻力损失和木芯质量损失率进行回归分析。还用腐朽和健康部分的电阻率均值定义了电阻率的异常程度,并对其和阻力损失进行了回归分析。以阻抗仪为基准在电阻率分布图上对腐朽部位定位,应用监督分类的方法在图上将腐朽与健康部分区分出来,并计算腐朽面积所占比例。然后用最小二乘法将算得的比例与木芯质量损失率作回归分析。结果表明:平均阻力损失与木芯质量损失率之间存在显著的线性相关关系,阻抗仪可以较准确地表征一维直线上的腐朽情况;微钻阻力变化曲线上发生阻力值明显下降的位置对应的电阻率也会发生明显变化,阻力损失值和电阻率异常程度存在显著指数关系,还能推断出电阻断层成像检测对于轻度腐朽更加敏感,而阻抗仪检测对较严重的腐朽更加敏感;联合阻抗仪和电阻断层成像技术能够确定腐朽的位置和面积,得到的腐朽面积所占比例与木芯质量损失率有显著线性相关关系。

In order to quantify the extent of wood decay of Korean pine（ Pinus koraiensis）,fifteen Korean pine standing trees were selected in Wuying National Forest Park of Heilongjiang Province of northeastern China. Resistograph and PiC US Treetronic ERT were applied to gain the variation of micro-drilling resistance and the distribution of cross-sectional electrical resistivity,which were compared in the same direction. Mass loss rate was measured through increment wood cores. Resistance loss,defined by the extent of micro-drilling resistance＇s decline,was compared with mass loss rate by regression analysis.Besides,abnormal extent of electrical resistivity was defined by the averages of electrical resistivity of decay and healthy portion and regression analysis was performed to derive the relation between it and resistance loss. The decay area can be located by the resistance curve on the electrical resistivity profile and computed through supervised classification. The percent of decay area we calculated was examined by its relation with mass loss rate with the method of ordinary linear square. The results indicated that： 1）the average of resistance loss had a significant linear relation with mass loss rate and Resistograph can be used to accurately detect the decay in one dimension. 2） Significant changes on the electrical resistivity profile took place where there was a noticeable decline on the micro-drilling resistance curve. Resistanceloss showed a significant exponential relationship with abnormal extent of electrical resistivity and it can also be deduced that ERT detection was more sensitive to mild wood decay,while Resistograph detection was sensitive to severe decay. 3） The location and area of wood decay can be confirmed by combining Resistograph and ERT technique and there was a high linear correlation between the percent of calculated decay area and mass loss rate.