Integrating profiling LIDAR with Landsat data for regional boreal forest canopy attribute estimation and change characterization
Integrating profiling LIDAR with Landsat data for regional boreal forest canopy attribute estimation and change characterization
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DOI：
10.1016/j.rse.2007.02.002
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发表时间：
2007-09
影响因子：
13.5
通讯作者：
M. Wulder;T. Han;Joanne C. White;T. Sweda;H. Tsuzuki
中科院分区：
文献类型：
--
作者：
M. Wulder;T. Han;Joanne C. White;T. Sweda;H. Tsuzuki
森林动态的特点是连续的（即，生长）和不连续（即，干扰）变化。利用光学遥感数据捕捉与干扰有关的变化的变化探测技术已经建立并得到普遍应用;然而，捕捉森林连续变化的方法还不太成熟。光学遥感图像非常适合于捕捉水平分布的状况、结构和变化，而光探测和测距（激光雷达）数据更适合于捕捉垂直分布的森林结构和变化要素。光学遥感图像和激光雷达数据的结合为充分确定森林冠层属性和动态提供了更好的机会。本文描述的研究捕获森林条件沿着约600公里长的走廊通过加拿大的北方森林。两个重合的激光雷达断面，分别代表1997年和2002年的森林条件，比较使用Landsat ETM+图像生成的图像片段。图像片段被用来提供一个空间框架内的属性和时间动态的森林冠层进行估计和比较。分割和分类的大地遥感卫星图像提供了一个背景，用于比较空间上充分相关的激光雷达剖面，并提供类别，以帮助应用需要土地覆盖知识的经验模型。采用全球和地方办法来描述森林属性随时间的变化。全球方法，强调森林变化的总体趋势，沿着整个样带的长度，并表明，关键的冠层属性是稳定的，样带的特点，包括森林冠层高度，没有显着变化，在本研究的五年期间（双样本t检验，p=0.08）。当地的方法分析了基于段的树冠属性的变化，提供空间上明确的森林生长和枯竭的迹象。当地的方法确定，84%的Landsat段拦截两个激光雷达断面没有变化，或有一个小的平均增加树冠高度（0.7米），而其他16%的段有一个平均减少树冠高度为1.6米。正如预期的那样，消耗的变化幅度差异明显大于增长，但空间范围较小。增长往往是在广阔的地区逐步发生的;而枯竭则是戏剧性的，而且在空间上受到限制。提出的方法具有潜在的调查气候变化的影响横跨纬度梯度的北方森林。
Forest dynamics are characterized by both continuous (i.e., growth) and discontinuous (i.e., disturbance) changes. Change detection techniques that use optical remotely sensed data to capture disturbance related changes are established and commonly applied; however, approaches for the capture of continuous forest changes are less mature. Optical remotely sensed imagery is well suited for capturing horizontally distributed conditions, structures, and changes, while Light Detection And Ranging (LIDAR) data are more appropriate for capturing vertically distributed elements of forest structure and change. The integration of optical remotely sensed imagery and LIDAR data provides improved opportunities to fully characterize forest canopy attributes and dynamics. The study described in this paper captures forest conditions along a corridor approximately 600 km long through the boreal forest of Canada. Two coincident LIDAR transects, representing 1997 and 2002 forest conditions respectively, are compared using image segments generated from Landsat ETM+ imagery. The image segments are used to provide a spatial framework within which the attributes and temporal dynamics of the forest canopy are estimated and compared. Segmented and classified Landsat imagery provides a context for the comparison of sufficiently spatially related LIDAR profiles and for the provision of categories to aid in the application of empirical models requiring knowledge of land cover. Global and local approaches were employed for characterizing changes in forest attributes over time. The global approach, emphasized the overall trend in forest change along the length of the entire transect, and indicated that key canopy attributes were stable, and transect characteristics, including forest canopy height, did not change significantly over the five-year period of this study (two sample t-test, p=0.08). The local approach analyzed segment-based changes in canopy attributes, providing spatially explicit indications of forest growth and depletion. The local approach identified that 84% of the Landsat segments intercepted by both LIDAR transects either have no change, or have a small average increase in canopy height (0.7 m), while the other 16% of segments have an average decrease in canopy height of 1.6 m. As expected, the difference in the magnitude of the changes was markedly greater for depletions than it was for growth, but was less spatially extensive. Growth tends to occur incrementally over broad areas; whereas, depletions are dramatic and spatially constrained. The approach presented holds potential for investigating the impacts of climate change across a latitudinal gradient of boreal forest.