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Scientia Silvae Sinicae ›› 2022, Vol. 58 ›› Issue (3): 1-9.doi: 10.11707/j.1001-7488.20220301

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Effects of Disturtance by Thinning on Productivity Stability of Conifer-Broadleaf Mixed Forest in Jiaohe, Jilin Province

Chen Liu,Chunyu Zhang*,Xiuhai Zhao   

  1. Key Laboratory of Forest Resources and Environmental Management of the National Forestry and Grassland Administration, Beijing Forestry University Beijing 100083
  • Received:2021-05-20 Online:2022-03-25 Published:2022-06-02
  • Contact: Chunyu Zhang

Abstract:

Objective: This paper aims to explore the effect of thinning disturbance on the productivity stability of stand productivity in a secondary natural mixed conifer-broadleaved forest in Jiaohe in Jilin province, in order to provide a theoretical basis for the sustainable management of mixed carboniferous forest. Method: Four sample plots with an area of 1 hm2 were established in the mixed forest in July 2011, thinning was conducted in December 2011 with a thinning intensity ranged from 2.7% to 77.6% with an average of 39.2%. The retained trees were measured in 2013, 2015 and 2018. using the data of woody plants obtained from 100 consecutive sample plots, the correlations of the thinning intensity, stand density, soil nutrient, tree size differentiation (DBH Shannon-Wiener index), species diversity (Species Simpson index) and the productivity stability were analyzed by using a linear regression model. Analysis of variance components was used to compare the contributions of different variables to the productivity stability. Furthermore, the effects of thinning on the tree size differentiation, the species diversity and the productivity stability and their inter-relations were analyzed by using structural equation model. Result: There was no significant correlation of the thinning intensity with the productivity stability, but a significant positive correlation of the species diversity and the tree size differentiation with the productivity stability (P < 0.05). The stand density had a significant negative impact on the productivity stability (P < 0.05). Among the variance components, that of species diversity alone contributed 19.5% of the productivity stability, those of the stand density and the tree size differentiation contributed to the productivity stability by 7.0% and 7.6% respectively. The thinning intensity had a significant negative effect on the stand density, the soil nutrients (the first principal component of soil carbon, nitrogen, phosphorus and calcium content) and the tree size differentiation (P < 0.001), and the path coefficients were -0.629, -0.316, and-0.255 respectively, but had no significant effect on the species diversity and the productivity stability. The stand density, the species diversity, and the tree size differentiation had significant effects on the productivity stability (P < 0.05), and the path coefficients were -2.063, 1.652 and 1.463 respectively. The stand and the tree size differentiation had significant negative effects on the productivity stability (P < 0.05), path coefficients were -2.365 and -0.556, and the species diversity had a significant positive effects on the productivity stability (P < 0.05), with a path coefficient of 1.652; the soil nutrients had no significant effects on the productivity stability; The thinning intensity had no significant direct impact on the productivity stability, neither indirect impact on the productivity stability through the species diversity and soil nutrients, but had significant indirect impact mainly through the stand density and the tree size differentiation. The thinning intensity has a significant negative effect on the productivity stability (P < 0.05), with a path coefficient of -0.290. Conclusion: The thinning intensity has no direct impact on the productivity stability. The stand density, the tree size differentiation and the species diversity have direct impact on the productivity stability. The thinning intensity indirectly influences the productivity stability through adjusting the stand density and the tree size differentiation, and further influences the variation of forest productivity. Therefore in forest management, a reasonable thinning interference is of great importance for promoting the stability of forest productivity.

Key words: thinning disturbance, forest management, tree size differentiation, species diversity, productivity stability, structural equation model

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