Leaf area density from airborne LiDAR: Comparing sensors and resolutions in a temperate broadleaf forest ecosystem
Leaf area density from airborne LiDAR: Comparing sensors and resolutions in a temperate broadleaf forest ecosystem
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DOI：
10.1016/j.foreco.2018.11.017
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发表时间：
2019-02-15
影响因子：
3.7
通讯作者：
Serbin, Shawn P.
中科院分区：
文献类型：
--
作者：
Kamoske, Aaron G.;Dahlin, Kyla M.;Serbin, Shawn P.
森林的光能利用效率、光合作用能力和微量气体交换等在固碳中起重要作用的森林过程与森林冠层的三维结构密切相关。然而，叶片性状的垂直分布并不均匀；由于不同的光照和环境条件，冠层内不同垂直位置的叶片在生理上是独一无二的，这导致了比整个冠层中光照条件恒定的情况下更高的碳储量。由于这种冠层内的变化，三维结构特征对于改进我们通过地球系统模型对全球碳循环和储存的估计以及更好地理解干扰对森林生态系统碳固存的影响至关重要。在这项研究中，我们描述了一种使用R编程语言从机载LiDAR估计叶面积密度(LAD；单位体积的总叶面积)的可重复性和开源的方法。使用这种方法，我们比较了美国马里兰州史密森环境研究中心的两个机载LiDAR系统，NEON AOP和NASA G-LiHT的LAD估计，这两个系统在测量和仪器规格、收集目标和激光脉冲密度方面存在差异。此外，我们讨论了分析的空间尺度以及冠层穿透和脉冲密度的差异对LAD和叶面积指数(LAI)估计的影响，同时提供了潜在的解决方案来提高这些估计的准确性。来自机载激光雷达的LAD估计可以用来描述整个景观中森林的三维结构。这些信息有助于为森林管理和养护决策提供信息，这些决策涉及估计地上生物量和生产力、森林对大规模干扰的反应、干旱对森林健康的影响、鸟类栖息地的保护以及许多其他重要的森林进程和对策。
Forest processes that play an essential role in carbon sequestration, such as light use efficiency, photosynthetic capacity, and trace gas exchange, are closely tied to the three-dimensional structure of forest canopies. However, the vertical distribution of leaf traits is not uniform; leaves at varying vertical positions within the canopy are physiologically unique due to differing light and environmental conditions, which leads to higher carbon storage than if light conditions were constant throughout the canopy. Due to this within-canopy variation, three-dimensional structural traits are critical to improving our estimates of global carbon cycling and storage by Earth system models and to better understanding the effects of disturbances on carbon sequestration in forested ecosystems. In this study, we describe a reproducible and open-source methodology using the R programming language for estimating leaf area density (LAD; the total leaf area per unit of volume) from airborne LiDAR. Using this approach, we compare LAD estimates at the Smithsonian Environmental Research Center in Maryland, USA, from two airborne LiDAR systems, NEON AOP and NASA G-LiHT, which differ in survey and instrument specifications, collections goals, and laser pulse densities. Furthermore, we address the impacts of the spatial scale of analysis as well as differences in canopy penetration and pulse density on LAD and leaf area index (LAI) estimates, while offering potential solutions to enhance the accuracy of these estimates. LAD estimates from airborne LiDAR can be used to describe the three-dimensional structure of forests across entire landscapes. This information can help inform forest management and conservation decisions related to the estimation of aboveground biomass and productivity, the response of forests to large-scale disturbances, the impacts of drought on forest health, the conservation of bird habitat, as well as a host of other important forest processes and responses.