Abstract:

The ministerial standard of two-variable tree volume tables has been applied for a total of 40 years.Whether or not the volume tables are still suitable for current status of forest resources has become a growing concern.Based on the recently collected individual tree volume data of 5 055 sample trees for 16 tree species or groups involving 41 modeling populations,the corresponding 43 two-variable tree volume tables in the ministerial standard were validated using statistical test and error test methods.The results showed that only less than 10 of 43 volume tables were still suitable or almost suitable for volume estimation nowadays,the other volume tables had prediction errors exceeding the allowance of ±3%,and about half of all volume tables had prediction errors exceeding ±5%,and a few of them even more than 10%.Based on the data of validation sample trees,41 compatible two-variable tree volume models were developed,of which 23 models have achieved the required precision,and only 5 models had prediction errors more than 5%,indicating that the developed volume models might be used in practice.It is suggested to update,revise and supplement the current two-variable tree volume tables,and gradually improve the tree volume accounting system of China.

Key words: volume table, prediction error, biased estimation, validation