Abstract: During the process of rapid urbanization, megacity has the radiation effects upon and can promote the urbanization of its adjacent small and mediumsized cities and towns. However, how the adjacent cities and towns response has not been well addressed yet. In this paper, the land use datasets derived from the time series color infrared aerial photos of 1989, 1994, 2000, and 2005 were employed to characterize the urban land growth of Songjiang district, a satellite city of Shanghai, and to demonstrate the effects of megacity on the urbanization of adjacent cities and towns. Under the effects of megacity urbanization and rapid regional economic development, the urban land growth of Songjiang district exhibited an obvious spatial anisotropy, and the development of the urban form presented a distinct centripetalism to megacity. The urban land in satellite city grew in an accelerated speed faster than that in megacity. Our results well testified the urban morphology theory of aggregation and diffusion during the urbanization process of megacity. Local governmental policy, economic development, population growth, and traffic infrastructure were the main driving forces of the urban growth of Songjiang district from 1989 to 2005.

Key words: Sinorhizobium fredii, Symbiotic plasmid, Nod factors, Nitrogen fixation