Remote sensing detection of droughts in Amazonian forest canopies
Remote sensing detection of droughts in Amazonian forest canopies
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DOI：
10.1111/j.1469-8137.2010.03355.x
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发表时间：
2010-01-01
期刊：
影响因子：
9.4
通讯作者：
Phillips, Oliver
中科院分区：
文献类型：
--
作者：
Anderson, Liana O.;Malhi, Yadvinder;Phillips, Oliver
P>；遥感数据是评估大面积森林地区的关键工具，这些地区普遍存在可获得性和缺乏实地测量等限制。本文分析了中分辨率成像光谱仪(MODIS)卫星测量数据和野外数据，以评估2005年亚马逊干旱的影响。我们结合植被指数(VI)和气候变量来评估与2005年干旱相关的时空格局，并探索遥感指数和森林资源清查数据之间的关系。C5VI与降雨量或气溶胶光学厚度没有显示出空间关系；然而，不同的区域对2005年增加的辐射有显著的响应。2005年增强型植被指数(EVI)的增加与林木死亡率的增加呈显著正相关(P<；0.07)。相比之下，归一化水分指数(NDWI)与树木死亡率呈显著负相关(P<；0.09)。以往的研究表明，2005年干旱期间EVI的增加与森林光合作用对辐射收入变化的正响应有关。我们讨论了这种增加可能与树冠结构变化有关的证据。
P>Remote sensing data are a key tool to assess large forested areas, where limitations such as accessibility and lack of field measurements are prevalent. Here, we have analysed datasets from moderate resolution imaging spectroradiometer (MODIS) satellite measurements and field data to assess the impacts of the 2005 drought in Amazonia.We combined vegetation indices (VI) and climatological variables to evaluate the spatiotemporal patterns associated with the 2005 drought, and explore the relationships between remotely-sensed indices and forest inventory data on tree mortality.There were differences in results based on c4 and c5 MODIS products. C5 VI showed no spatial relationship with rainfall or aerosol optical depth; however, distinct regions responded significantly to the increased radiation in 2005. The increase in the Enhanced VI (EVI) during 2005 showed a significant positive relationship (P < 0.07) with the increase of tree mortality. By contrast, the normalized difference water index (NDWI) exhibited a significant negative relationship (P < 0.09) with tree mortality.Previous studies have suggested that the increase in EVI during the 2005 drought was associated with a positive response of forest photosynthesis to changes in the radiation income. We discuss the evidence that this increase could be related to structural changes in the canopy.