Optimizing the Remote Detection of Tropical Rainforest Structure with Airborne Lidar: Leaf Area Profile Sensitivity to Pulse Density and Spatial Sampling
Optimizing the Remote Detection of Tropical Rainforest Structure with Airborne Lidar: Leaf Area Profile Sensitivity to Pulse Density and Spatial Sampling
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DOI：
10.3390/rs11010092
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发表时间：
2019-01-01
期刊：
影响因子：
5
通讯作者：
Santin Brancalion, Pedro Henrique
中科院分区：
文献类型：
--
作者：
Alves de Almeida, Danilo Roberti;Stark, Scott C.;Santin Brancalion, Pedro Henrique
机载激光扫描（ALS）已被认为是一个主要来源，通过指标叶面积指数（LAI）和叶面积密度（LAD）的垂直冠层剖面模拟森林冠层的结构和功能。然而，很少有人知道的激光脉冲密度和激光点云的粒度（水平分箱分辨率）的LAD剖面和它们相关的莱什的估计的影响。我们的目标是确定可靠和稳定的估计LAD配置文件从ALS数据在茂密的热带森林的最佳值。使用三种方法比较配置文件：破坏性现场采样，便携式冠层剖面激光雷达（PCL）和ALS。当晶粒尺寸小于10 μ m且脉冲密度高（>15脉冲m（-2））时，ALS获得了稳定的LAD分布，与其他两种分析方法一致。当使用适当的调整（系数K）时，较低的脉冲密度也提供了稳定和可靠的LAD曲线。我们还讨论了如何LAD配置文件可能会被纠正在整个景观时，使用ALS调查的密度较低，通过校准与LAI测量在现场或从PCL。适当选择的粒度，脉冲密度和K提供了可靠的估计LAD和相关的树样地人口和生物量在茂密的森林生态系统。
Airborne Laser Scanning (ALS) has been considered as a primary source to model the structure and function of a forest canopy through the indicators leaf area index (LAI) and vertical canopy profiles of leaf area density (LAD). However, little is known about the effects of the laser pulse density and the grain size (horizontal binning resolution) of the laser point cloud on the estimation of LAD profiles and their associated LAIs. Our objective was to determine the optimal values for reliable and stable estimates of LAD profiles from ALS data obtained over a dense tropical forest. Profiles were compared using three methods: Destructive field sampling, Portable Canopy profiling Lidar (PCL) and ALS. Stable LAD profiles from ALS, concordant with the other two analytical methods, were obtained when the grain size was less than 10 m and pulse density was high (>15 pulses m(-2)). Lower pulse densities also provided stable and reliable LAD profiles when using an appropriate adjustment (coefficient K). We also discuss how LAD profiles might be corrected throughout the landscape when using ALS surveys of lower density, by calibrating with LAI measurements in the field or from PCL. Appropriate choices of grain size, pulse density and K provide reliable estimates of LAD and associated tree plot demography and biomass in dense forest ecosystems.