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Scientia Silvae Sinicae ›› 2020, Vol. 56 ›› Issue (9): 184-192.doi: 10.11707/j.1001-7488.20200920

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Basal Area Growth Model for Oaks Natural Secondary Forest in Hunan Province Based on Storey Identification

Song Hu1,Guangyu Zhu1,3,*,Zhenxiong Chen2,Kan Lu1,Lang Huang1,Zhuo Liu1   

  1. 1. Forestry College, Central South University of Forest&Technology Changsha 410004
    2. Central South Forest Inventory and Planning Institute of National Forestry and Grassland Administration Changsha 410014
    3. Key Laboratory of State Forestry Administration on Forest Resources Management and Monitoring in Southern Area Changsha 410004
  • Received:2018-06-07 Online:2020-09-25 Published:2020-10-15
  • Contact: Guangyu Zhu

Abstract:

Objective: This paper was implemented to study the effects of forest storey of multi-storied stand on Oaks natural forest basal area growth model in Hunan Province. It would reflect the basal area growth rules of different storeys by building basal area growth models from the perspective of forest storey in order to provide references for the growth harvesting and management of the Oaks natural secondary forest in Hunan Province. Method: After the storey identification by using whole tree height clustering,IUFRO standard and TRSRAT,the model of Schumacher was used to fit the basal area of whole stand,upper layer and lower layer based on the 51 plots of Oaks natural secondary forest in Hunan Province,and the optimal method of storey identification was selected. Considering the compatibility of the total basal area and each forest layer basal area,the compatible storey basal area growth model was built by adjustment in proportion. Result: The results of storey identification by whole tree height clustering,IUFRO standard and TRSRAT were all satisfied with the requirements of technical regulations for forest resources planning and design investigation,and the F testing of different forest layer statistics were significant. The model of Schumacher could better simulate the growth of whole stand and different forest layers,the coefficients of determination (R2) were all above 0.92. Compared with the whole stand basal area growth model without storey identification,the coefficient of determination (R2) of different forest layers with storey identification was increased from 0.925 9 to 0.945 5-0.984 6.The IUFRO standard was selected as the optimal method of storey identification,and the accuracy of the basal area growth model was the highest (R2=0.970 4,MAE=1.458 8,RMSE=2.178 6).Compared with the whole stand basal area growth model without storey identification,the determination coefficient (R2) was increased by 5.0%,the mean absolute error (MAE) and the root mean square error (RMSE) was respectively decreased by 39.8% and 26.4%. The proportional adjustment method based on total basal area could better solve the problem of the compatibility between total basal area and each forest layer basal area. Compared with the independent prediction model of each forest layer,the determination coefficient (R2) of upper layer was increased from 0.974 6 to 0.986 8,and the determination coefficient (R2) of lower layer was increased from 0.980 2 to 0.988 8. Conclusion: The effects of forest storey of multi-storied stand on Oaks natural forest basal area growth model in Hunan Province was significant. It was important to study the characteristics of different forest storeys and improve the modeling accuracy by considering storey effection. The research results were expected to reveal the growth process of forest basal area in subtropical Oaks forest,which was of great significance to growth harvesting and management of the Oaks natural secondary forest.

Key words: storey identification, basal area growth model, adjustment in proportion, compatible, Oaks

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