The Effects of Resin Tapping on the Radial Growth of Masson Pine Trees in South China-A Case Study

Abstract

Five Masson pine (Pinus massoniana Lamb.) plantations near Liuzhou, Guangxi in south China ranging in age from 14-18 years were selected for this study. Two plantations were tapped for resin production and three plantations had not been tapped. Eight sample trees were selected from each of three sample plots randomly established in each plantation. Tree cores were extracted at 1.3m on each sample tree for the purpose of measuring tree ring width to establish radial growth. Tree cores were sanded with fine grain sandpaper and measured to the nearest 0.5mm with the aid of a 10x magnification scope. Some cores had to be eliminated from the sample due to poor quality, and ultimately 24 cores from tapped trees and 24 cores from untapped trees were used for analysis. The mean radial growth of tapped trees (4.4712mm) and untapped trees (4.3537) were found to be not significantly different (p=0.05). Models were developed to display the cumulative radial growth of trees, and the 95% confidence bounds about the model coefficients suggest there is no significant difference in the cumulative radial growth of tapped and untapped trees. While our results would suggest that there is no impact of tapping trees for resin on diameter radial growth, this might be misleading. We sampled only at 1.3m and it is possible that had we sampled at 3.0m we might have recorded a negative effect. The “non-effect” we recorded at 1.3m may actually have been a positive effect. There could have been an increase in the radial growth due to the wood formation in the uninjured side of the tree, but was not significantly greater than that of untapped trees. Implications of this finding are discussed.