Comparison of lidar- and allometry-derived canopy height models in an eastern deciduous forest
Comparison of lidar- and allometry-derived canopy height models in an eastern deciduous forest
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DOI：
10.1016/j.foreco.2017.10.005
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发表时间：
2017-12
影响因子：
3.7
通讯作者：
F. Sullivan;M. Ducey;D. Orwig;B. Cook;M. Palace
中科院分区：
文献类型：
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作者：
F. Sullivan;M. Ducey;D. Orwig;B. Cook;M. Palace
树冠的几何形状和高度，特别是在与遥感数据相结合时，可有助于确定树木和森林结构的特征。在这项研究中，我们开发的混合效应模型异速生长方程树高，树冠半径，树冠深度使用的数据收集在374棵树的范围内的联合热带森林科学中心（CTFS）和史密森学会的森林全球地球观测站（ForestGEO）MegaPlot的前景山在哈佛森林，马萨诸塞州。我们将异速生长应用于前景山35公顷地块的人口普查，以使用激光雷达冠层高度模型评估树高和树冠半径估计值。用胸径和树种估测树高（ρ r ~ 2 = 0.70，RMSE = 2.96 m）、冠深（ρ r ~ 2 = 0.35，RMSE = 3.24 m）和冠径（ρ r ~ 2 = 0.43，RMSE = 1.22 m）的相关性显著。使用快速傅立叶变换（FFT），我们比较了激光雷达冠层高度模型的功率谱的高度和树冠半径的异速生长估计来自五个合成冠层高度模型。FFT显示激光雷达和合成冠层高度模型（CHM）之间的空间波长超过64米，或约3-4个主要树冠的距离，在较短的空间波长，较差的协议，我们归因于简单的树冠形状应用于建模冠和缺乏冠重叠的合成CHM相比，激光雷达CHM。在树的水平上，一些物种表现出激光雷达测量的高度和估计的树高之间的紧密联系（例如，红栎，绒栎，松strobus），表明高度异速生长提供了合理的估计树高的一些物种，尽管负偏差的合成冠层高度模型相对于激光雷达冠层高度模型。
Tree crown geometry and height, especially when coupled with remotely sensed data, can aid in the characterization of tree and forest structure. In this study, we develop mixed-effects model allometric equations for tree height, crown radius, and crown depth using data collected on 374 trees across 14 species within the extent of the joint Center for Tropical Forest Science (CTFS) and Smithsonian Institute’s Forest Global Earth Observatory (ForestGEO) MegaPlot on Prospect Hill at Harvard Forest, Massachusetts. We applied allometry to a census of the 35-ha plot on Prospect Hill to evaluate tree height and crown radius estimates using a lidar canopy height model. We found significant relationships using stem diameter-at-breast-height (DBH) and species to estimate tree height (ρr2= 0.70, RMSE = 2.96 m), crown depth (ρr2= 0.35, RMSE = 3.24 m) and crown radius (ρr2= 0.43, RMSE = 1.22 m). Using Fast Fourier Transforms (FFTs), we compared the power spectra of a lidar canopy height model to five synthetic canopy height models derived from allometric estimates of height and crown radius. The FFTs showed good agreement between lidar and synthetic canopy height models (CHMs) at spatial wavelengths longer than 64 m, or about the distance across 3–4 dominant tree crowns, and poorer agreement at shorter spatial wavelengths, which we attribute to the simple crown shape applied to modeled crowns and a lack of crown overlap in the synthetic CHMs compared to the lidar CHM. At the tree level, some species exhibited tight links between lidar-measured height and estimated tree height (e.g.,Quercus rubra,Quercus velutina,Pinus strobus), suggesting height allometry provided reasonable estimates of tree height for some species despite a negative bias in the synthetic canopy height models relative to the lidar canopy height model.