Landscape pattern gradient dynamics and desakota region features of three mega-cities in Asia-Pacific developing countries

With the support of 3S (GIS,GPS and RS) technology and based on recent 20 years remote-sensing data,the landscape pattern dynamics and desakota region features related with the urbanization of three mega-cities in Asia-Pacific Region,i.e.,Shanghai (China),Metro Manila (the Philippines),and Hanoi (Vietnam),were studied by gradient analysis with six landscape matrix indices including contagion index,largest patch index,landscape shape index,perimeter-area fractal dimension,patch density,and Shannon diversity index. In the process of urbanization,the regional landscape pattern of the three cities changed markedly,with an increase of patch density and fragmentation. In land use transects,the patch density and Shannon diversity index had higher correlations with the absolute distance to city center. Landscape index could detect the gradient and the direction of urbanization. The desakota regions of the three cities had different development features,and the urbanization process of the cities was at different stages. Metro Manila was found at the highest stage of urbanization,and with the earliest suburb urbanization and obvious desakota region. Shanghai was demonstrated a high degree of urbanization,and an obvious suburb urbanization and desakota region. In contrast,Hanoi had lower level of urbanization and unobvious suburb urbanization and desakota region. Ecological environment protection for the desakota regions should be strengthened.