微钻阻力法测量早晚材密度的可行性试验

Feasibility study on measuring density of earlywood and latewood by micro drill resistance method

为微损、快速测量树木早晚材密度,提出了一种基于微钻阻力的早晚材密度测量方法。使用自制微钻阻力仪和德国Resistograph 650-S微钻阻力仪测量了10个辐射松长方体木块的钻针阻力,使用体积法测量了各生长轮的早材绝干密度和晚材绝干密度。以木材绝干密度为因变量,以每个生长轮早材部分和晚材部分对应的平均阻力值为自变量,使用4/5的试验数据分别建立2个微钻阻力仪钻针阻力与早晚材绝干密度的线性回归模型,使用1/5的试验数据分别测试2个微钻阻力仪早晚材绝干密度的测量精度。结果表明:自制微钻阻力仪测得的早晚材钻针阻力与绝干密度的线性相关系数为0.657,早晚材绝干密度的平均测量精度为87.111%;Resistograph 650-S测得的早晚材平均阻力与木材绝干密度的线性相关系数为0.655,早晚材绝干密度的平均测量精度为85.811%。研究认为:2个仪器测量的早晚材绝干密度平均精度高达86%,说明微钻阻力法测量早材绝干密度和晚材绝干密度可行;自制微钻阻力仪测得的早晚材平均阻力与木材绝干密度的线性相关系数和早晚材密度的平均测量精度均高于Resistograph 650-S,说明自制微钻阻力仪机械结构设计合理,钻针阻力表示方式可行。

The density measurement of earlywood and latewood is a difficult task in forestry research.In order to measure the density of earlywood and latewood quickly and nondestructively,based on the micro drill resistance,an earlywood and latewood density measurement method was proposed.The drill resistances of 10 rectangular wood blocks of Pinus radiata were measured by the self-made micro drill resistance instrument and the tool of Resistograph 650-S.The earlywood and latewood samples were split by a knife and the absolute dry densities of earlywood and latewood of each growth ring were measured by the volume method.The absolute dry wood density was taken as the dependent variable,and the average drill resistance corresponding to the earlywood or latewood of each ring was taken as the independent variable.Using 4/5 of the test data,the linear regression models of two micro drill resistance instruments between the drill resistance and the absolute dry wood density were established,respectively.Using the surplus 1/5 of the test data,the accuracies of two micro drill resistance instruments in measuring the absolute dry densities of earlywood or latewood were evaluated,respectively.The results showed that the correlation coefficient of self-made micro drill resistance instrument testing between the drill resistance and absolute dry density of earlywood or latewood was 0.657,and the accuracy of measuring absolute dry density of earlywood or latewood was 87.111%.The linear correlation coefficient of Resistograph 650-S testing between the average resistance of earlywood or latewood and the absolute dry wood density was 0.655,and the accuracy of measuring the absolute dry density of earlywood or latewood was 85.811%.The P value of t test between the predicted density of earlywood or latewood by the self-made micro drill resistance instrument was 0.796,and that between the predicted density of earlywood or latewood by Resistograph 650-S was 0.808,so there was no significant difference between the absolute dry density predicted by the two micro drill resistance instruments and the actual measured absolute dry density at the significance level of 0.1.It was feasible to measure the absolute dry density of earlywood and latewood of growth rings by the micro drill resistance method;the average measurement accuracy of the density of earlywood or latewood measured by the self-made micro drill resistance instrument was higher than that of Resistograph 650-S,which indicated that the mechanical structure of the self-developed micro drill resistance instrument and the expression method of drill needle resistance were feasible for measuring density of earlywood and latewood.