Study Research On The Measurement Technique Of Stumpage Factors And The Analysis Of Its Accuracy

In the traditional forestory survey and dynamic monitoring work, instruments and measuring methods used by researchers are relatively simple which causes a poor accuracy. This research aims to study the principles, methods and accuracy of measuring techniques through the analysis of five stumpage factors including DBH, height, volume, increment and diameter at anywhere of the tree, using two precise tree measuring instruments including electronic theodolite and total station. These include:(1) DBH measurement was carried out with the help of Diameter tape. Every sample tree was measured40times by one person and four people in a total. Tree species include needle-leaf trees and broad-leaf trees. Analysis of systematic errors of DBH measurement indicate that there exits no systematic errors in diameter tape;standard deviation analysis shows a high accuracy of DBH measurements; binary tree variance analysis shows that reseachers and tree species have a great impact on the diameter measured values. Therefore, in DBH measurements, accuracy can be improved if researchers are more carefull. Tree height was measured using tree measuring guns and every sample tree was measured40times by one person and four people in a total. The tree height measured by total station was set as relative true value. Systemetic error analysis of tree height measured by tree measuring guns shows that tree height measurement through tree measuring guns does not have system errors; Standard deviation analysis show that measurement accuracy of the tree height is greatly affected by the observers and tree species. So, in diameter and height measurements, measurement accuracy can be improved if the researchers are more careful and able to treat the trees differently according to their different species.(2)20sample trees were measured before and after parsing, using tree measuring electronic theodolite and total station. The parsed data of felled wood is regarded as "referential true value". The accuracy of the tree height measured by the two instruments are98.67%and98.72%respectively. The accuracy of the diameter at anywhere of the tree are95.57%and95.40%respectively. The tree volume are97.43%and98.42%respectively. Statistics indicate that these instruments can be used to accurately measure stumpage factors and at the same time can be used to supplement the accurate measurement of stumpage factors before hewing down.(3) Use a small amount of parsed wood to fit the optimal growth model and verify. The correlation coefficient of the growth model on tree height, diameter, volume were0.8566,0.9297and0.9595respectively. The fitting effect is satisfactory and the model can be used for production practice. This illustrates the feasibility of building growth model with a small amout of samples. Apart from those instruments, the use of needle detector was also recommended to conduct accurate and undamaged measurement on tree growth rings and supplement and perfect the accurate measurement system on stumpage factors from time and space dimension.