APGC特集号論文
Monitoring of Vegetation Damage Caused by the 2000 Miyake Island Volcanic Eruption Using Satellite Remote Sensing and Field Surveys
2005 年 60 巻 6 号 p. 1183-1188
詳細
2005 年 60 巻 6 号 p. 1183-1188
Mt. Oyama on Miyake Island, in the Izu Islands of Japan, erupted in 2000. Indigenous plants and animals were badly affected by the volcanic deposits and gases. We analyzed satellite images to estimate vegetation cover and to assess long-term vegetation damage on the island. We then classified changes in vegetation cover between l995 and 2003 and compared the classification with field survey data.
We compared fractional vegetation cover (fC) interpreted from aerial photographs with cover estimated from remote sensing data to select the best equation for estimating fC. The following equation best estimates vegetation cover on Miyake Island:
fC=[(NDVI-NDVImin)/(NDVImax-NDVImin)]2 × 100%
where NDVI is the Normalized Difference Vegetation Index, and NDVImin and NDVImax are the minimum and maximum values.
We estimated vegetation cover on Miyake Island using this equation and by analyzing 8 satellite images from 1995 to 2003. The main phases of volcanic activity occurred from July to August 2000, when almost all vegetation was damaged, mainly by volcanic ash. On the foothills of the mountain, vegetation damaged by volcanic ash gradually recovered. However, damage has spread along the eastern part of the mountain since autumn 2000, probably owing to the volcanic gases emitted since September 2000.
Vegetation cover was classified from 6 satellite images from 2000 to 2003. Vegetation was classified into 6 classes based on the change of vegetation cover. The state of vegetation damage in each area corresponded well with the results of the field survey. In almost all areas, species composition changed after the eruption. The classification map will provide basic data for conservation efforts and recovery.
