Lidar remote sensing of the canopy structure and biophysical properties of Douglas-fir western hemlock forests
Lidar remote sensing of the canopy structure and biophysical properties of Douglas-fir western hemlock forests
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DOI：
10.1016/s0034-4257(99)00052-8
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发表时间：
1999-12-01
影响因子：
13.5
通讯作者：
Harding, D
中科院分区：
文献类型：
--
作者：
Lefsky, MA;Cohen, WB;Harding, D
扫描激光雷达遥感系统最近可用于生态应用。与传统的微波和光学传感器不同，激光雷达传感器直接测量植被材料沿垂直轴的分布，并可用于提供植被结构的三维或体积特征。迄今为止，扫描激光雷达的生态应用一直使用一维指数来表征冠层高度。提出了一种新的三维激光雷达波形分析方法，用于表征森林冠层内植被物质和空地的总体积和空间组织。很少使用现场或远程方法测量冠层物理结构的这些方面。我们将此分析应用于俄勒冈州卡斯卡德山脉西坡道格拉斯冷杉/西部铁杉林的22个样地。每个样地的激光雷达数据与林分结构的野外测量结果一致。我们将新分析的结果与两种早期的冠层描述方法进行了比较。利用这三种描述方法的冠层结构指数作为自变量，在逐步多元回归中，我们能够在很大的范围内对生物量和叶面积指数（LAI）进行非渐近预测，最高可达1200 Mg ha（-1）生物量和叶面积指数（LAI）为12，分别解释了90%和75%的方差。此外，我们还能够准确地估计林分结构的其他属性，包括胸高处直径的平均值和标准差、直径大于100 cm的树的数量以及道格拉斯冷杉和西部铁杉的基底面积的独立估计。这些测量可以与林分结构复杂性指数直接相关，例如那些为原生林特征而开发的指数。利用新的三维分析方法建立的冠层结构指标占逐步多元回归预测方程中使用的大部分变量。Elsevier Science Inc.出版。
Scanning lidar remote sensing systems have recently become available for use in ecological applications. Unlike conventional microwave and optical sensors, lidar sensors directly measure the distribution of vegetation material along the vertical axis and can be used to provide three-dimensional, or volumetric, characterizations of vegetation structure. Ecological applications of scanning lidar have hitherto used one-dimensional indices to characterize canopy height. A novel three-dimensional analysis of lidar waveforms was developed to characterize the total volume and spatial organization of vegetation material and empty space within the forest canopy. These aspects of the physical structure of canopies have been infrequently measured, from either field or remote methods. We applied this analysis to 22 plots in Douglas-fir/western hemlock stands on the west slope of the Cascades Range in Oregon. Each plot had coincident lidar data and field measurements of stand structure. We compared results from the novel analysis to two earlier methods of canopy description. Using the indices of canopy structure from all three methods of description as independent variables in a stepwise multiple regression, we were able to make nonasymptotic predictions of biomass and leaf area index (LAI) over a wide range, up to 1200 Mg ha(-1) of biomass and art LAI of 12, with 90% and 75% of variance explained respectively. Furthermore, we were able to make accurate estimates of other stand structure attributes, including the mean and standard deviation of diameter at breast height, the number of steins greater than 100 cm in diameter and independent estimates of the basal area of Douglas-fir and western hemlock. These measurements can be directly related to indices of forest stand structural complexity, such as those developed for old-growth forest characterisation. Indices of canopy structure developed using the novel, three-dimensional analysis accounted for most of the variables used in predictive equations generated by the stepwise multiple regression. Published by Elsevier Science Inc.