JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2025, Vol. 49 ›› Issue (2): 185-193.doi: 10.12302/j.issn.1000-2006.202306010

Previous Articles     Next Articles

Extraction and construction of a QSM-based model of first-order branches of Larix gmelinii plantations

PENG Wenyue1,2(), JIA Weiwei1,3,*(), WANG Fan1, LI Xin1,2, LI Dandan1   

  1. 1. School of Forestry, Northeast Forestry University, Harbin 150040, China
    2. Forestry Investigation and Planning Institute of Jilin Province, Changchun 130607, China
    3. Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, Northeast Forestry University, Harbin 150040, China
  • Received:2023-06-13 Accepted:2023-09-21 Online:2025-03-30 Published:2025-03-28
  • Contact: JIA Weiwei E-mail:1246584738@qq.com;jiaww2002@163.com

Abstract:

【Objective】The quantitative structural model (QSM) algorithm was used to extract the number of first-order branches at different relative branch depths using a fully automatic strategy based on terrestrial laser scanning (TLS) point cloud data. A linear mixed prediction model of first-order branch density was constructed to provide a theoretical basis for research studies on Larix gmelinii plantation canopies. 【Method】 The TLS data of 30 L. gmelinii plantations and the QSM algorithm were used to obtain parameters pertaining to tree structure, and the extracted and measured values were subjected to regression analysis for exploring the accuracy of modeling based on point cloud data. The extraction accuracy of the method used for determining the number of first-order branches at different relative branch depths was assessed using the point cloud layering method. The optimal mixing model of the first-order branch density of the sample tree effect was constructed using the Poisson regression model, and the model was evaluated. 【Result】 The average extraction accuracy of the model constructed based on 30 L. gmelinii plantation branches was 80.71%, and the RMSE was 6.959 4. There were differences among the number of first-order branches extracted from different canopies, and the best results were obtained when the relative branch depth ranged from 0.7 to 0.8. The average accuracy was 87.78%, and a mixed model based on the sample tree effect was found to be optimal for determining the first-order branch density. The optimal model of branch density was a linear mixed model based on three random effect parameters, namely natural logarithm of the relative branching depth [ln(RDINC)], square of the relative branching depth (RDINC2), and ratio of tree height to breast diameter [HT/DBH], and the values of R2 and RMSE were 0.745 4 and 0.229, respectively. 【Conclusion】 The parameters pertaining to the branch structure of individual trees were obtained based on the ground-based laser radar scanning data, using the quantitative structure model that was applicable or reliable. Based on the effects observed in the sample wood, the density mixed model of the first-order branches of L. gmelinii plantations not only reflects the changes in the distribution density of the primary branches in the canopy, but can also predict the overall growth trend of the crown.

Key words: Larix gmelinii, point cloud data, number of first-order branches, quantitative structural model (QSM), linear mixed model

CLC Number: