森林资源二类调查方法的改进及角规抽样监测体系的建立

Improvement of Forest Inventory Method for Management Plan and Stand Growth Estimation on Horizontal Point Sample

针对我国森林资源二类调查方法与体系的现状进行了分析,采用小班不等概抽样及固定角规点抽样的方法建立森林资源动态监测体系。在理论上论述了小班不等概抽样的估计公式,并给出了具体的证明。在样本组织与估计方面提出了采用利用小班抽样主特征因子与抽样概率成比例的辅助因子、相关系数的方法,指出了采用先验信息具体确定相关系统的估计方法。在动态监测体系中具体给出了采用保留木确定小班蓄积生长量的具体公式。该方法避免了常规二类调查需采用县级加密样地控制方法耗资大、难操作的缺点,使森林资源二类调查自成体系,有利于小班调查与森林生态区域及环境调查结合,实现动态多层次监测。

This paper analyzed the situation of forest inventory for management plan in China. Three problems were put forward. The first was how to control the precision of whole subcompartments survey. The system sampling method with dense plots on the base of national forest inventory plots was often used to control the precision of subcompartment survey. But now the method can＇t be used because of expensive survey and longer survey time. The second is how to use survivors on horizontal points sample to estimate the stand growth. The third is how to combine the subcompartment survey with ecological investigation. Using the sampling method with probability proportional to an estimation of size, we can establish the independent sampling system of subcompartment. It ensured the precision of the measure es timation. In order to increase the efficiency of this sampling method, we do the main measures of subcompartment such as the volume which is proportional to the sampling probabili ty. The values of volume, forest coverage or areas of subcompartment, which get from last surveys, was used as an estimation size. In addition, using the remote sensing data and method, we also completed the subcompartment sampling discussed above. According to the principal of sampling with probability proportional to an estimate of size, we carried out the subcompartment sampling. For the Selected sampling subcompartment, we put forward per manent horizontal point sample plots, which are well distributed and are decided on the size of subcompartment. The bigger the size of subcompartment is, the more number of sample plots is. In sample plots, the angle is used to measure the stand basal areas and volume. For the remeasured plots, the method of measuring survivors growth in permanent point sampiing was used to get the growth estimation of per sampling subcompartments. Fornewly numbered tree in sampling plots, the measurements are only made, which will be as new survivors on next inventory. So the sampling system based on subcompartment has been established. If the eco combined the forest i measures of subcomp important role in the logical regions are described by the composed subcompartments, we nventory with ecological investigation, which can not only enhance the artment management into that of ecology and environment but also play forest management field.