Airborne Lidar-derived volume metrics for aboveground biomass estimation: A comparative assessment for conifer stands
Airborne Lidar-derived volume metrics for aboveground biomass estimation: A comparative assessment for conifer stands
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DOI：
10.1016/j.agrformet.2014.07.008
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发表时间：
2014-11
影响因子：
6.2
通讯作者：
S. Tao;Q. Guo;Le Li;Baolin Xue;M. Kelly;Wenkai Li;Guangcai Xu;Yanjun Su
中科院分区：
文献类型：
--
作者：
S. Tao;Q. Guo;Le Li;Baolin Xue;M. Kelly;Wenkai Li;Guangcai Xu;Yanjun Su
估算陆地生态系统地上生物量（AGB）是量化陆地生态系统碳平衡的关键，在全球气候变化的背景下变得越来越重要。个体树木的体积指标，例如树干体积，已被证明与AGB密切相关。在本文中，我们比较了一系列的机载激光雷达衍生的体积度量（即树干体积，树冠体积下凸船体，树冠高度模型（CHM）下的树冠体积），以估计AGB。此外，我们评估了水平冠重叠（这是经常被忽视的激光雷达文献）的AGB估计的准确性的影响，通过使用一种混合的方法，结合标记控制的分水岭分割和点云分割算法。我们的研究结果表明：（1）在不考虑树冠水平重叠问题的情况下，基于点云分割的模型优于基于标记控制分水岭分割的模型;基于树干蓄积量的模型比基于凸船体下树冠蓄积量和CHM下树冠蓄积量的模型更准确地估计AGB。(2)一旦考虑到水平树冠重叠问题，CHM下使用树冠体积的模型产生了更准确的AGB估计。我们的研究提供了一个全面的评估使用机载激光雷达衍生的体积度量AGB估计，可以帮助研究人员选择适当的机载激光雷达衍生的体积度量。此外，研究结果还表明，水平树冠重叠时，应解决机载激光雷达导出的森林树冠体积用于估计AGB。
Estimating aboveground biomass (AGB) is essential to quantify the carbon balance of terrestrial ecosystems, and becomes increasingly important under changing global climate. Volume metrics of individual trees, for example stem volume, have been proven to be strongly correlated to AGB. In this paper, we compared a range of airborne Lidar-derived volume metrics (i.e. stem volume, crown volume under convex hull, and crown volume under Canopy Height Model (CHM)) to estimate AGB. In addition, we evaluated the effect of horizontal crown overlap (which is often neglected in Lidar literature) on the accuracy of AGB estimation by using a hybrid method that combined marker-controlled watershed segmentation and point cloud segmentation algorithms. Our results show that: (1) when the horizontal crown overlap issue was not addressed, models based on point cloud segmentation outperformed models based on marker-controlled watershed segmentation; models using stem volume estimated AGB more accurately than models using crown volume under convex hull and crown volume under CHM. (2) Once the horizontal crown overlap issue was taken into consideration, the model using crown volume under CHM yielded a more accurate estimation of AGB. Our study provides a comprehensive evaluation of the use of airborne Lidar-derived volume metrics for AGB estimation and could help researchers choose the appropriate airborne Lidar-derived volume metric. Moreover, the results also indicate that horizontal crown overlap should be addressed when the airborne Lidar-derived forest crown volume is used for estimating AGB.