Comparison of Change Estimation between Four Ground-Survey Methods for Use in a Continuous Forest Inventory System

概要

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In this study we compare the accuracy with which four ground-survey techniques estimate change. The methods compared are; point sampling (PS), line sampling (LS), circular plot (CP), and concentric circular plot (CCP), which can all be used as permanent samples in a continuous forest inventory system. Data were collected on two occasions from a sugi (Cryptomeria japonica D. DON) stand in the Takakuma Experimental Forest, Kagoshima Prefecture, Japan. For the PS and LS methods a basal area factor of 4 was used. For the LS method, the line length was 10 m, and the stems on both sides of the line were selected. For the CP method, the radius was 6 m, corresponding to 0.011 ha; and for the CCP method, the radii were 5 and 10 m, corresponding to 0.008 and 0.031 ha respectively. Twelve samples were systematically sampled and the process repeated 10 times for each method. The CP method was the most accurate for estimating the change in the number of stems per hectare, but there were no significant differences between the four methods for estimating basal area or volume.
森林計画学会の論文