Abstract:

1/5 of the survey samples were organized by systematic sampling,stochastic sampling and cluster sampling based on the framework of national continuous forest inventory,respectively,and joint estimation was carried out.Sampling efficiency was analyzed by sampling ratio,sampling accuracy and sampling organization.Results showed that,with 95% reliability,the average estimation accuracy of stochastic sampling,second-stage systematic sampling and second-stage cluster sampling was 94.70%,lower than continuous forest inventory estimation accuracy,but greater than 94.50%.The mean correlation coefficient R between the estimated value of the standing volume,biomass and carbon storageand observations of systematic sampling,stochastic sampling and cluster sampling were 0.97,0.99 and 0.96,respectively.The relative difference RD% were -0.28,-0.14 and -0.14,respectively.The goodness of sampling scheme in the order of the largest to the smallest were stochastic sampling,systematic sampling and cluster sampling with comprehensive analysis.Stochastic sampling could reduce the effects of human disturbance on estimation results.Cluster sampling with counties as a group could effectively reduce the cost of transfer in practice.However,due to the large difference between different groups,the sampling error caused by this is often greater than stochastic sampling.

Key words: sampling technique, annual monitoring, forest resources, continuous forest inventory