Abstract:

Tree volume tables are important basic tools in forest inventory and monitoring.One-variable tree volume tables have been used in continuous forest inventories (CFIs) of China for more than 40 years,but we have never systematically tested the applicability in nowadays.In this paper,the general status of currently used one-variable tree volume tables were analyzed from the aspects of quantity,zoning,tree species,and model type;and most of one-variable tree volume tables were examined by using the tree height data of 138 911 sample trees.The results showed that the total number of one-variable tree volume tables used in China's CFI reached 707,and the number of provincial volume tables varied greatly,from 3 to 171;there were 18 provincial regions divided into several modeling populations,while others were based on whole provincial regions;there were also great differences in the number of tree species groups for developing tree volume tables in each provincial region,with the least being 3 and the most being 31;a total of 25 models were used to develop tree volume tables,but nearly 90% of the tree volume tables were based on 5 models;about 70% of the one-variable tree volume tables exceeded the allowable error limit of ±5%,and 10 of 31 provincial regions and four forest industry groups exceeded the range of ±10% of the volume estimation errors,among which the maximum negative bias was -14.86% and the maximum positive bias was 23.22%.Based on the results of analysis,it is suggested that at the end of this inventory,a comprehensive and systematic applicability test should be carried out on the current one-variable tree volume tables;and unified revision should be made on the tree volume tables with significant deviation,so as to optimize and adjust the division of modeling populations,tree species grouping and the volume model type;and the change of volume estimation method from one-variable table to two-variable table should be actively promoted.

Key words: one-variable tree volume table, continuous forest inventory, tree height curve, volume estimation error