As the most dominant fast-growing timber species in China, exploring the response of aboveground biomass to stand spatial structure parameters in Chinese fir () is of great significance for improving forest quality and carbon sequestration capacity. In this study, we used unmanned aerial vehicle (UAV) point cloud data to extract forest parameters and constructed weighted Voronoi diagrams to determine the spatial structure units of the forest to realize rapid acquisition of the spatial structure parameters of the forest stand. Combined with the biomass model constructed using 20 harvested logs, we used stepwise regression to explore the key factors of the spatial structure of Chinese fir that affect biomass accumulation at different age stages. The results showed that: (1) the angle competition index should be kept in the range of (0,0.25] for the biomass of the Chinese fir to be maximized at the young, near-mature, mature, and overmature forest stages; (2) the openness ratio affects the accumulation of the Chinese fir biomass, and its optimal range changes continuously during the growth process from (0.25,0.5]- (0.75,1]-(0.5,0.75] and subsequently has been at (0.5,0.75]; (3) in the mature and overripe forest stages, the forest layer index further affects biomass accumulation, and its optimal range varies from (0.25,0.5] to (0.5,0.75]; (4) in the five Chinese fir growth stages, biomass accumulation was more favorable when the number of nearest trees change was 7, 6, 6, 6, and 5; (5) adopting reasonable measures to regulate the spatial structure of forest stands at different age stages can effectively enhance the biomass of Chinese fir. At the young, middle-aged, and mature forest stages, ensuring the optimal number of neighboring trees through reasonable dense planting and nursery thinning is essential; at the near-mature and mature forest stages, enhancing the use of vertical space of the forest trees by trimming the branches and trunks is crucial.

中文翻译：

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基于无人机的杉木人工林空间结构提取及其对AGB的影响

杉木作为我国最主要的速生用材树种，探讨杉木地上生物量对林分空间结构参数的响应对于提高森林质量和固碳能力具有重要意义。本研究利用无人机点云数据提取森林参数，构建加权Voronoi图确定森林的空间结构单元，实现林分空间结构参数的快速获取。结合20根采伐原木构建的生物量模型，采用逐步回归的方法探讨影响杉木不同龄期生物量积累的空间结构关键因素。结果表明：（1）幼林、近熟、成熟和过熟林阶段，角度竞争指数应保持在（0，0.25）范围内，杉木生物量才能达到最大；（ 2）开孔率影响杉木生物量的积累，其最佳范围在生长过程中不断变化，从(0.25,0.5]-(0.75,1]-(0.5,0.75]，随后一直在(0.5,0.75) 0.75]；（3）在成熟林和过熟林阶段，林层指数进一步影响生物量积累，其最佳范围为（0.25，0.5]至（0.5，0.75）；（4）在五种杉木生长中各阶段，最近树数变化为 7、6、6、6、5 时，生物量积累较为有利；（5）采取合理措施调控不同龄期林分空间结构，可有效提高林木生物量。杉木：在幼林、中龄、成熟林阶段，通过合理的密植和间苗，保证邻树的最佳数量；在近成熟和成熟森林阶段，通过修剪枝干来提高林木垂直空间的利用至关重要。