利用MODIS数据评估冷冻灾害对广东植被的损害

Assessing vegetation damage from cold disaster in Guangdong using MODIS data

2008年初我国南方地区发生的极端冷冻灾害对植被造成了极大破坏。以广东为例,利用MODIS数据,对比分析了受损植被与正常植被的NDVI变化;利用ISODATA非监督分类方法提取受损植被分布信息,借助90m SRTM DEM数据研究受损植被与地形因子的关系,发现广东植被受损严重,受损植被总面积达19 011.06 km2。受损植被受海拔高程、坡度、坡向等地形因子影响较大;受损植被主要集中于海拔大于400 m,坡度小于15°的阴坡区域;通过MODIS土地覆盖图与受损植被的复合分析,研究了该地区受损植被的类型,发现受损植被以常绿阔叶林、混交林、落叶阔叶林、灌丛、落叶针叶林及常绿针叶林为主。

An extreme disaster of snow and cold took place at the beginning of 2008 and caused great damage to vegetation in South China. Taking Guangdong as an example, the authors analyze NDVI changes of damaged vegetation and healthy vegetation using MODIS data, extract distribution information of damaged vegetation through ISODATA algorithm of unsupervised classification method, and study the relationships between damaged vegetation and topography factors using 90 m SRTM DEM data. The results showed that vegetation in Guangdong was damaged seriously, with a damaged area reaching to 19 011.06 km^2, and it was greatly affected by topography factors such as elevation, slope and aspect. Damaged vegetation mainly distributed in shady hillside with elevation higher than 400 m and slope less than 15°. Through overlap analysis between IGBP vegetation map and damaged vegetation, it was found that damaged vegetation mainly covered the evergreen broadleaf forest, mixed forest, deciduous broadleaf forest, shrubbery, deciduous coniferous forest and evergreen coniferous forest.