Comparison of vegetation patch dynamics after the eruptions of the volcano Mount Usu, northern Japan, in 1977-1978 and 2000, detected by imagery chronosequence
Comparison of vegetation patch dynamics after the eruptions of the volcano Mount Usu, northern Japan, in 1977-1978 and 2000, detected by imagery chronosequence
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1977-1978年和2000年日本北部有珠火山喷发后植被斑块动态的比较，通过影像时序检测
DOI：
10.1111/1440-1703.12199
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发表时间：
2021
影响因子：
2
通讯作者：
Shiro Tsuyuzaki
中科院分区：
文献类型：
--
作者：
Lea Vegh;Shiro Tsuyuzaki
分析了日本北部USU火山上两个地点(山顶于1977-1978年被摧毁，山麓Konpira于2000年被摧毁)喷发后的植被斑块动态，以检测植被发展模式。利用2000年、2006年和2014年拍摄的航空照片和卫星图像，建立了植被斑块动态的图像时间序列。植被斑块通过卫星图像的归一化差异植被指数(NDVI)和航空照片的归一化绿红差异指数(NGRDI)来识别。我们根据斑块是否与未来的植被斑块重叠(接触)或不重叠(孤立)以及它们的面积是增加(增长)还是减少(缩小)来划分植被斑块类型。然后，通过斑块类型、密集植被和斑块生长随坡度、海拔和时间的变化，比较了两个地点的斑块动态。在峰会上，孤立的斑块被建立得更多，并显示出高死亡率，而在孔皮拉，大多数孤立的斑块存活到2006年，到2014年合并为感人的斑块。此外，孔皮拉的斑块植被密度高于山顶。补丁的增长与两个站点的补丁类型有关。然而，时间对山顶的斑块动态更重要，植被密度对Konpira的动态影响更大。因此，这两个地点的植被斑块动态不同，这与地形和喷发的特点有关。总而言之，这项研究中提出的图像时间序列很好地监测了斑块的动态，并且Konpira的斑块发展得更快。
Vegetation patch dynamics were analyzed to detect vegetation development patterns after eruptions on two sites (summit destroyed in 1977–1978, and a foothill, Konpira destroyed in 2000) on the volcano Mount Usu, in northern Japan. Aerial photos and satellite images taken in 2000, 2006, and 2014 were used to develop an imagery chronosequence of vegetation patch dynamics. Vegetation patches were identified by the Normalized Difference Vegetation Index (NDVI) for satellite images, and by the Normalized Green‐Red Difference Index (NGRDI) for aerial photos. We categorized the vegetation patch types based on whether the patches overlapped (touching) or not (isolated) with the future vegetation patches and whether their area increased (growing) or decreased (shrinking). Afterwards, patch dynamics were compared between the two sites through changes in patch types, dense vegetation, and patch growth with slope degree, elevation, and time. Isolated patches were established more at the summit and showed high mortality, while at Konpira most isolated patches survived until 2006 and merged into touching patches by 2014. Moreover, the vegetation density of patches was higher at Konpira than at the summit. Patch growth was associated with patch types at both sites. However, the time was more important for the patch dynamics at the summit, and the vegetation density affected the dynamics more at Konpira. Therefore, the two sites had different vegetation patch dynamics, which were related to the characteristics of topography and eruptions. In conclusion, the imagery chronosequence proposed in this study monitored patch dynamics well, and patches developed faster at Konpira.