JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2022, Vol. 46 ›› Issue (5): 121-126.doi: 10.12302/j.issn.1000-2006.202103030

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Distributions of knots in trunks and pruning effects on growth in Castanopsis hystrix

XU Fang(), YANG Xiaohui, PAN Wen(), LIAO Huanqin, YANG Huixiao, ZHANG Weihua, ZHU Baozhu, CHEN Xinyu, XU Bin, WANG Yuxia   

  1. Guangdong Key Laboratory of Silviculture, Protection and Utilization, Guangdong Academy of Forestry, Guangzhou 510520, China
  • Received:2021-03-10 Revised:2022-04-11 Online:2022-09-30 Published:2022-10-19
  • Contact: PAN Wen E-mail:xufang@sinogaf.cn;panwen@sinogaf.cn

Abstract:

【Objective】 After investigating the distribution of knots in Castanopsis hystrix and performing a pruning experiment on them, a new pruning management method was developed to reduce the formation of knots in the trunk, promote plant growth and enable the cultivation of large-diameter-grade and knot-free wood. 【Method】 The time and distribution of knot formation in the trunk were determined by investigating the scar distribution in six naturally grown 30-year-old individiuals. Different pruning intensities were then set for trees in a six-year plantation, and growth after 18 months of pruning was measured to select the best intensity. Three types of common paint were selected for pruning incision protection. The healing and transverse sections of incision were investigated to evaluate the protective effects of the radial growth after pruning. 【Result】 The knots were mainly distributed in the core of the trunk, with 87% dead knots. The best pruning intensity demonstrated a 26.1% increase in the diameter at breast height (DBH) growth compared with the control, but no significant difference with the other pruning intensities. All the incision protection methods can increase the healing rate and protect the incision rot from extending into deeper areas. Oil paint exhibited the best protecting effect, and the healing rate of incision reached 94.2% and 84.1% for diameters under and greater than 3.5 cm, respectively. Post-incision necrosis deeper than 3.5 cm can be reduced by 61.2%, and pruning can significantly change the inhibition of the radial growth under the branch area. 【Conclusion】 The pruning method summarized in this study is operable and can improve growth and roundness, reduce the formation of wood knots, and appropriate for the management of C. hystrix plantations.

Key words: Castanopsis hystrix plantation, pruning intensity, wood knot, growth, incision protection

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