基于地空激光雷达的池杉人工林林分空间结构优化

Optimization of Taxodium ascendens Plantation Stand Spatial Structure Based on Terrestrial and Airborne LiDAR

【目的】以池杉人工林为研究对象,融合地空激光雷达点云数据,评估林分空间结构特征,为池杉人工林质量提升和可持续经营提供科学依据和理论支持。【方法】以仙女林场2块30 m×30 m池杉样地的无人机激光雷达、地基激光雷达和野外实地调查数据为数据源,融合点云数据后进行单木分割和单木参数提取,选择角尺度、大小比数、空间密度指数、开敞度、生长空间指数、生长空间竞争指数、简单竞争指数等7个参数构建综合评价模型。通过综合评价模型进行模拟采伐,选取最优采伐强度,对林分空间结构优化策略进行评估。【结果】与实测数据对比,地空激光雷达的胸径和树高的提取精度R^(2)均值分别为0.9883、0.9853,均方根误差均值分别为0.4939 cm、0.1255 m;A、B样方的林分空间结构综合指数为0.526、0.349,通过模拟采伐选取的A、B两个样方的最优采伐强度分别为总蓄积6%、8%,该采伐强度能够在不过量采伐基础上,使林分空间结构综合指数分别上升0.067、0.132,有效地改善林分内树木的生长环境和降低资源竞争压力。【结论】利用地空激光雷达融合可高效实现林分结构信息的数字化、精细化,克服单一激光雷达和传统人工存在的局限性,对于人工林资源调查与监测具有重要的实际意义;利用综合评价模型对池杉人工林的空间结构进行综合评估和模拟采伐可以指导林分空间结构优化,为林分改造与森林质量提升提供科学依据和实践参考。

【Objective】This study aims to evaluate the spatial structure characteristics of a Taxodium ascendens plantation by integrating terrestrial and airborne LiDAR point cloud data,providing scientific basis and theoretical support for the quality improvement and sustainable management of the plantation.【Method】Data sources included UAV LiDAR,terrestrial LiDAR,and field survey data from two 30 m×30 m Taxodium ascendens plots in Xiannv Forest Farm.After merging the point cloud data,individual tree segmentation and parameter extraction were performed.Seven parameters—angular scale,size ratio,spatial density index,openness,growth space index,growth space competition index,and simple competition index were selected to construct a comprehensive evaluation model.The comprehensive evaluation model was used to perform simulated logging,and the optimal logging intensity was selected to evaluate the optimization strategy of the forest spatial structure.【Result】Compared with the measured data,the extraction accuracy of diameter at breast height(DBH)and tree height from terrestrial and airborne LiDAR data had average R^(2) values of 0.9883 and 0.9853,with mean squared error values of 0.4939 cm and 0.1255 m,respectively.The comprehensive spatial structure index of plots A and B was 0.526 and 0.349,respectively.Through simulated logging,the optimal logging intensity for plots A and B was found to be 6%and 8%of the total volume,respectively.This logging intensity,without excessive logging,increased the comprehensive spatial structure index by 0.067 and 0.132,respectively,effectively improving the growth environment within the forest and reducing resource competition pressure.【Conclusion】The integration of terrestrial and airborne LiDAR can efficiently digitize and refine stand structure information,and overcome the limitations of single LiDAR systems and traditional manual methods.This approach has significant practical implications for the survey and monitoring of plantation resources.Utilizing a comprehensive evaluation model to assess the spatial structure of Taxodium ascendens plantations and simulate logging can guide the optimization of stand spatial structure,providing a scientific basis and practical reference for stand transformation and forest quality improvement.