基于森林资源二类调查数据的香格里拉市森林生物量二阶抽样优化

Optimal Design of Second-order Sampling for Forest Biomass in Shangri-La City Based on the Forest Management Inventory

以香格里拉市针叶林为研究对象,确定95%可靠性指标和85%抽样精度,选取1 km×1 km、2 km×2 km、3 km×3 km、4 km×4 km、5 km×5 km、6 km×6 km、7 km×7 km、8 km×8 km、9 km×9 km、10 km×10 km共计10种一阶抽样单元规格,基于二阶抽样的一阶单元间方差差异,对二阶抽样进行优化设计,进而对比分析优化前后二阶抽样方法的抽样误差和抽样精度。结果表明:在10种未优化二阶抽样单元中6 km×6 km的抽样单元具有最小的抽样误差和最高的抽样精度,其抽样误差值为9.12%,抽样精度为90.88%;经二阶抽样优化后,10种抽样单元的抽样精度均明显提升,抽样误差明显降低,其中6 km×6 km的抽样单元抽样误差最小为6.39%,抽样精度最高为93.61%。本研究中优化后的二阶抽样方法具有较好的抽样精度和实用性,可为今后的森林生物量调查提供精度保障。

Taking the coniferous forests in Shangri-La City as the object of research and determine the 95%reliability index and 85%sampling accuracy,a total of 10 first-order sampling units specifications of 1 km×1 km,2 km×2 km,3 km×3 km,4 km×4 km,5 km×5 km,6 km×6 km,7 km×7 km,8 km×8 km,9 km×9 km and 10 km×10 km were selected in the second-order sampling(SOS)method,then an optimal design of SOS was carried out based on the variance difference between first-order units elements of SOS.Finally,the sampling error and sampling accuracy of both sampling methods were compared and analyzed.The results showed that among the 10 kinds of SOS,the sampling error of the 6 km×6 km has the lowest error and highest accuracy,and the sampling error is 9.12%,the sampling accuracy is 90.88%.After the optimization,the sampling accuracy of SOS are improved and sampling error decreased significantly.Especially,the sampling error of the 6 km×6 km sampling unit is 6.39%and a sampling accuracy of 93.61%.Therefore,the optimized SOS has the better overall accuracy and practicability,which could be used to forest biomass investigation with the accuracy guarantee.