Selection of Resin Accelerators and Analysis on Resin Yield of Different Forest Stand Ages of Initial Resin-tapping of Pinus elliotti

In order to develop safe and environmentally friendly resin accelerator and explore the appropriate stand age of initial resin-tapping of P. elliotti, the differences of increasing ratios of resin yield among different resin accelerator treatments and the differences of resin yield and growth of three forest stand ages （ 9 a, 13 a and 15 a ） of initial resin-tapping of Pinus elliottii were analyzed respectively by resin- tapping test in this paper. The results showed that: （1） There were significant differences among those resin yield increasing ratios of resin accelerators in different treatments. The resin yield increasing ratio of No.5 resin accelerator was 30.69%, the second highest increasing ratio of resin yield, next to the control resin accelerator CK₁, with no significant difference between the two. While No.5 resin accelerator was non-corrosive and environmentally friendly. （2） There were significant differences on resin yield among different forest stand ages of initial resin-tapping of P. elliottii. The resin yields per tapping of forest stand with initial resin-tapping age of 15 a in 2018 and in 2019 were 86.18 g and 76.49 g respectively, were significantly higher than those of forest stand with initial resin-tapping age of 13 a and 9 a. The diameter growth rate was significantly different between resin-tapping trees and control trees after 2 years of resin tapping. The diameter growth of trees tapped at the initial age of 15 a was minimally affected by two years of tapping, its growth rate was only reduced by 4.15%. The above results indicate that, the firth resin accelerator was the optimal resin accelerator of P. elliottii for safety and environmental protection in this study. Considering resin yield and diameter growth rate, the optimal forest stand age of initial resin-tapping of P. elliottii was 15 a.