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Scientia Silvae Sinicae ›› 2021, Vol. 57 ›› Issue (9): 87-97.doi: 10.11707/j.1001-7488.20210909

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Individual Tree Diameter Growth Model of Chinese Fir Plantations Using Bayesian Model Averaging and Stepwise Regression Approaches

Lele Lu1,2,Zhen Wang1,Xiongqing Zhang1,2,*,Jianguo Zhang1   

  1. 1. Key Laboratory of Tree Breeding and Cultivation of National Forestry and Grassland Administration Research Institute of Forestry, CAF Beijing 100091
    2. Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University Nanjing 210037
  • Received:2020-06-24 Online:2021-09-25 Published:2021-11-29
  • Contact: Xiongqing Zhang

Abstract:

Object: Individual tree diameter growth model is one of forest growth and yield basic models. Stepwise regression is widely used in the selection of model variables. However, this method ignores the model uncertainty caused by the variable selection process. So the driving factors of individual tree diameter grouth of Chinese fir (Cunninghamia lanceolata) plantation were explored, the importance of different driving factors was compared, and the uncertain individual tree diameter growth model was constructed, in order to provide reference for Chinese fir managers to manage Chinese fir plantation scientifically. Method: Data for this study was sampled from Chinese fir stands in Weimin, Shaowu city, Fujian Province. Bayesian model averaging(BMA) and stepwise regression(SR) were used to analyze the effects of endogenous and climatic factors on the individual tree diameter growth of Chinese fir. Result: Competition and individual tree size were the main factors affecting annual diameter growth comparing with climate factors. Diameter growth decreased with the increase of tree number per hectare, quadratic mean diameter, sum of basal areas of trees larger than the subject tree(BAL), age and winter mean minimum temperature, whereas increased with the increase of diameter at the beginning of growth period, stand basal area, dominant height, mean coldest month temperature, mean warmest month temperature and mean annual precipitation. For most of the treatments of the four models, the posterior probability of the model obtained by SR was smaller than that of the best model obtained by BMA(which exhibited the highest posterior probability). In some cases, SR models did not belong to the top several models with higher posterior probability in the BMA model space. Conclusion: The diameter increment decreased with increasing competition and increased with increasing temperature and precipitation. BMA considered the combination of all possible variables and reflected the uncertainty of the model.

Key words: individual tree diameter growth, climate variables, Bayesian model averaging(BMA), stepwise regression(SR), stand variables

CLC Number: