张家港市耕地资源安全与城市化时空动态分析

在1991、1996、2001和2006年Landsat遥感影像的支持下,研究了张家港市近20 a间的城市增长模式和城市化土地利用强度,结果表明:在3个研究时期中,张家港市主城区的城市化由以新发生型为主兼有延展型的扩张模式,发展成为以填充型为主要的扩张模式,而农村地区城市化则由新发生型为主的扩张模式,转变为新发生型与延展型并存的扩张模式;张家港市的城市化土地利用强度I有明显的阶段性,1991—1996年为主城区城市化时期(I峰值出现在4 km处),1996—2001年为城市化缓慢发展时期(I值较低且变化平缓),从2001—2006年开始张家港市进入了农村城市化时期(I峰值出现在22 km处)。随着农村地区经济的快速发展和城市化进程的加剧,以张家港市为代表的长江三角洲地区中小型城市的耕地不断被工业用地和居住用地吞噬,耕地资源安全受到严重威胁,必须引起高度重视,只有正确处理好城市化发展与农地保护之间的客观矛盾才能保证耕地资源安全和经济可持续发展。

Cultivated Land Resources Security and Spatial-temporal Dynamics of Urbanization in Zhangjiagang, Jiangsu

Cultivated land resource security has been one of the most important problems in the world. In order to study the effects of urbanization on cultivated land resource security, the spatial-temporal dynamics of growth typology and land use intensity were analyzed using Landsat remotely sensed imageries of 1991, 1996, 2001 and 2006. Results indicated that: 1) In the main town urbanization phase, the urban edge-expansion growth appeared in urban center areas (S=0.41 in urban center between 1991 and 1996, S=L_c/P, where L_c is the length of the common boudary of a newly grown urban area and the pre-growth urban patches, and P is the perimeter of this newly grown area), while in the rural urbanization phase, the urban infilling growth was obvious in urban center areas (S=0.85 in urban center between 2001 and 2006). In rural areas, the urban spontaneous growth was dominant in the main town urbanization phase (S=0.15 in 16 km between 1991 and 1996), while both urban spontaneous growth and urban edge-expansion growth coexisted in rural urbanization phase (S=0.39 in 16 km between 2001 and 2006). 2) Land use intensity(I) of Zhangjiagang urbanization changed by stages. The phase from 1991 to 1996, 1996 to 2001 and 2001 to 2006, was main town urbanization (the maximum of I appeared in 4 km), slow urbanization (the value of I was low and fluctuated smoothly), and rural urbanization (the maximum of I appeared in 22 km), respectively. As the rapid development of urbanization in rural areas of Zhangjiagang, the cultivated land resources security was threatened seriously.