Abstract:

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.

Key words: sampling survey, sub-compartment survey, verification plot, data coupling, stratified sampling