开展森林资源一体化监测,实现样地调查数据与图斑调查数据的有机结合,是我国森林资源调查监测的发展趋势。基于2020年国家森林资源年度监测评价北京市试点项目数据资料,提出利用校验样地修正更新森林面积数据、利用地面样地分层估计森林储量数据的基本思路,并研究提出了具体算法和计算公式。结果显示,基于点面结合的方法,森林面积和乔木林面积估计值的精度能达到99%以上;3项储量指标(蓄积量、生物量、碳储量)的估计精度能达到95%左右。研究表明:基于校验样地修正更新森林面积数据、基于地面样地分层估计森林储量数据的做法,在实践中是可行的;基于校验样地计算森林面积和乔木林面积时,只需分别按森林、非森林和乔木林、非乔木林分2个层即可;计算每层的均值和方差时,应当采用不等整群抽样估计方法。

It is the development trend of forest resources inventory and monitoring in China to conduct integrated monitoring and realize data combination of sample plot survey and sub-compartment survey. Based on the pilot data of national annual forest resources monitoring and assessment in Beijing in 2020,the basic idea of revising and updating forest area data from verification plots and estimating forest stock data from ground plots by stratified sampling was put forward,and the specific algorithm and calculation formula were presented. The results showed that the precisions of forest area and arboreal forest area estimates based on the combination of sample plot survey and sub-compartment survey were more than 99%,and those of three forest stock statistics (volume,biomass,and carbon storage) were about 95%. The following conclusions can be achieved:(i) it was feasible in practice to revise and update forest area data based on verification plots and to estimate forest stock data based on stratified ground plots; (ii) when estimating forest area and arboreal forest area based on verification plots,only two strata of forest and non-forest,or arboreal forest and non-arboreal forest were needed; and when calculating the mean and variance for each stratum,the unequal cluster sampling method should be used.