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红树林是国际上生物多样性保护和湿地生态保护的重要对象,及时获取红树林面积变化是加强红树林保护的迫切需求.以福建漳江口红树林国家级自然保护区为研究区域,对2007年多时相的ALOS PALSAR数据进行处理,分析红树林与各典型地物L波段HH、HV极化的后向散射值的时间变化特征及去极化特征.红树林在L波段HH和HV极化的后向散射随时间变化不明显,与其它林地较为相似,但两者去极化能力差异明显.相时于时相信息,极化信息对于提取红树林的作用更为重要.基于面向对象分类方法,提出应用HH、HV和HV与HH比值进行红树林提取的方法,取得较好的分类结果.“,”Mangrove forest is an important vegatation type on biodiversity conservation and wetland ecologi-cal protection. Acquisition changes on mangrove area timely is an urgent need for protection. In this paper, taking Fujian Zhangjiang Estuary National Nature Reserve as study area,multi-temporal ALOS PALSAR data acquired in 2007 are processed. The temporal change characteristics and depolarization characteristics on L band HH,HV channel are analyzed. On L band HH、HV channel, backscatter information does not change significantly over time, which is similar to local forests, but depolarization ability between mangrove forests and local forests is obviously different. Compared to temporal information, polarization information is more important for mangrove forests extraction. Based on object-oriented approach classification ,we pro-posed a method for mangrove forests extraction by using HV, HH polarization and their ratio from a mono temporal data. The results show that mangrove can be extracted with high accuracy.