Establishment of the Site Index Table for Betula alnoides Plantations in Dehong Prefecture, Yunnan Province

PurposeTo establish the site index table of Betula alnoides plantations in Dehong Prefecture, Yunnan Province based on the object from five counties or cities.

MethodA total of 65 plots were set up for growth investigation. One dominant tree was selected from each plot for stem analysis and 1009 pairs of tree height-tree age data were obtained. The method of three-time standard deviation was used to eliminate the abnormal data, then eight common equations such as Korf, Richards and Weibull were selected to fit the 1000 pairs of dominant height-tree age data, and the guide curves were selected by comparing the model statistics indexes including the determination coefficient (R²), absolute residual error (AMR), root mean square error (RMSE) and relative absolute residual (RAR). The standard deviation adjustment method was used to compile the site index table, and the Chi-square test, prediction accuracy test and landing point test were further conducted for the table.

ResultThe Richards equation with the largest R², the smallest AMR, RMSE and RAR was selected as the guide curve, and the equation expression was H=39.4531−exp(−0.067t)^1.018. Reference tree age was determined as 15 years, eight site index classes were divided by taking two meters as the index interval, and the site index table was established. Through Chi-square test, prediction accuracy test and drop point test, it was proved that the site index table was qualified.

ConclusionThe site index table developed in the present study can be used to evaluate the site quality of B. alnoides plantations in Dehong Prefecture and similar areas, and to improve plantation management of the species.