A Study Of Method On Forest Stock Volume Estimation Based On Multi-sampling

With the development of China’s economy, the ecological environment has become a victim of rapid economic development. Thus recent years, China gradually began to pay attention to the ecological balance, eighteen also proposed to build a socialist ecological civilization, has even mentioned the most important ecological problems. Forests as an important component of terrestrial ecosystems, ecological environment construction is duty-bound to contribute. The forest stock volume is an important indicator of the status quo of the merits of forest resources, so an accurate estimate of forest stock volume has an important role and significance.In this study, the three sampling methods to estimate forest stock volume were moderately optimized and improved, and the Three Gorges Reservoir to accurately estimate the overall forest stock volume and various county forest stock volume, the amount of accumulated survey a larger area in the future foundation. The main conclusions obtained are as follows:(1) In terms of the number of field monitoring plots, third field monitoring plots the number of third-order-based sampling methods to estimate forest stock volume of up to 33,571, and the plot size is 100m × 100m, is a large plot; the number of last-order field monitoring plots based encryption multistage sampling method to estimate forest stock volume of only 3184, while the inventory of a class of Three Gorges Reservoir permanent plots have 3660; multi-stage stratified based encryption The number of forest stock volume sampling method to estimate the final stage of field monitoring plots 876, compared to the previous two methods, with a large advantage in the number of field monitoring plots.(2) Analysis and comparison of the three methods, the sampling accuracy and precision of the estimated overall terms, based on third-order sampling precision sampling methods to estimate forest stock volume was 87.16%, to estimate the overall accuracy of 99.52% based on multi,; forest stock volume sampling to estimate the accuracy of the order of encryption sampling method was 89.72%, to estimate the overall accuracy of 92.49%; multi-stage stratified sampling precision encryption based sampling methods to estimate forest stock volume was 99.01%, estimate the overall accuracy reached 99.47%. Three methods, the sample is based on the most accurate multi-stage stratified sampling encryption method for estimating forest stock volume of 99.01%, based on sampling to estimate the overall accuracy of the third-order method for estimating forest stock volume of up to 99.52%.(3) For the county forest stock volume estimation in terms of maneuverability and precision, based on third-order forest stock volume estimation sampling method is the use of the Three Gorges reservoir area accumulation unit estimates the county accumulation, and thus less accurate; forest stock volume estimation method based on multi-stage sampling encryption, considered by seeking the county district last fall field monitoring plots in order volume per unit area to give the county’s forest stock volume,26 counties in 20 counties estimate the overall accuracy of 90%, and estimate the overall accuracy of three counties in between 80%-90%, only three lower counties estimate the overall accuracy; encryption-based multi-stage stratified sampling accumulation per unit area of forest stock volume estimation method, calculate the direct request of the county multistage encrypted plots to obtain forest stock volume of the county, there are 26 districts in 18 counties to estimate the overall accuracy of 90% or more, estimate the overall accuracy of seven counties between 80% and 90%, only one county due to the actual accumulation amount is too small, estimate the overall accuracy of 78.83%, the overall accuracy is relatively stable.(4) To sum up, based on multi-stage stratified sampling encryption methods to estimate forest stock volume in the field to monitor the number of plots and sampling precision both have a clear advantage, estimate the overall accuracy of each county’s forest stock volume and overall forest stock volume estimate the overall accuracy of the Three Gorges reservoir almost all above 90%, also reached precision, so use this method to estimate forest stock volume both feasible and efficient.