珠江口近20年红树林湿地的遥感动态监测

应用多种规则相结合的专家系统方法，对珠江口地区3个时相的遥感图像进行分类，得到3个时相的红树林面积变化和空间分布变化。结果表明，从1988年到2002年珠江口地区红树林的整体面积变化是一种先降低再增长的趋势，但红树林类型由分散分布的天然林转变为集中分布的人工林，除淇澳岛、深圳河口地区还有大片的红树林外，其它地区的红树林基本消失。

MONITORING OF THE CHANGES OF MANGROVE WETLAND AROUND THE ZHUJIANG ESTUARY IN THE PAST TWO DECADES BY REMOTE SENSING

Monitoring and protection of mangrove wetland have become an urgent task in some fast developing areas in south China. Remote sensing can be used to obtain the information about mangrove wetland, such as the monitoring of mangrove changes. The information is important for wetland conservation in rapidly developing areas, such as the Zhujiang Delta. One of the purposes for monitoring mangrove wetland is to detect the mangrove area and analyze the trends of wetland changes. In this study, three temporal Landsat TM images are used to monitor the wetland changes in the Zhujiang estuary. The techniques of expert systems are applied to the classification of the wetland with the combination of various rules. The analysis results clearly show the fluctuations for the areas of mangrove forests in the past two decades. Many natural mangrove forests have disappeared because of reclamation projects. Only those in the reserves, such as the Qi'ao Island, Futian, and Mai Po's mangrove forests, have been well protected under strict conservation policies. The monitoring can provide useful information for assessing the effectiveness of policy implementation.