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林下植被在森林生态系统碳、水和营养元素的累积和循环方面有着重要作用与科学意义。多角度、高光谱和激光雷达遥感系统凭借对森林分层结构的敏感性,成为量化林下植被的重要手段。本文综述了森林林下植被的遥感反演研究进展:首先讨论了林下植被的定义,其次对当前林下植被的遥感反演现状作了深入分析,总结了多角度、高光谱和激光雷达遥感观测的森林背景的反射率、林下植被的叶面积指数、高度和覆盖度的遥感反演原理和方法。基于不同卫星观测角度下森林冠层和森林背景对总反射的贡献差异,林下反射率可通过多个角度的观测数据进行反演。此外,借助激光雷达穿透冠层直接观测林下植被的优势,总结了激光点云数据和回波波形信息反演林下植被的覆盖度和高度的方法,以及今后使用遥感技术反演的难点和获取林下植被信息的主要发展方向。
Undergrowth vegetation plays an important role and scientific significance in the accumulation and circulation of carbon, water and nutrients in forest ecosystems. Multi-angle, hyperspectral and lidar remote sensing systems, with their sensitivity to stratification of forests, have become an important tool for quantifying understory vegetation. This paper reviews the research progress of remote sensing inversion of forest understory vegetation. Firstly, the definition of understory vegetation is discussed. Secondly, the current situation of remote sensing inversion of understory vegetation is analyzed in depth. The multi-angle, hyperspectral and lidar remote sensing Observed forest background reflectance, undergrowth vegetation leaf area index, height and coverage of remote sensing retrieval principles and methods. Based on the contribution of forest canopy and forest background to the total reflection under different satellite observations, the subtropical forest reflectance can be inversed by observational data from multiple angles. In addition, by using the advantages of Lidar penetrating the canopy to directly observe the undergrowth vegetation, this paper summarizes the methods of using the laser point cloud data and the echo waveform information to retrieve the coverage and height of the undergrowth vegetation, as well as the difficulties of using the remote sensing technology in the future And get the main development direction of forest vegetation information.