苏州市非农用地扩张对土壤资源影响的时空特征

基于1984~2003年期间的4期Landsat TM影像以及由苏州市土壤图得到的土壤质量综合评价图,研究利用遥感及GIS空间分析手段阐释了城市化发展走在全国前列的苏州市的非农用地扩张在不同质量土壤资源上的时空过程,并比较了城镇与农村地区各自非农用地扩张对高质量土壤占用的贡献大小。结果表明,苏州市非农用地占用的土壤资源中,面积最大的是二等高质量土壤,达到92.10%,其次便是一等最高质量的土壤,而对三、四等土壤的占用比例仅占1.95%,几乎可以忽略。通过对城镇与农村地区非农用地各自对土壤资源的扩张占用在时间尺度上的分析发现,在城镇地区,土壤质量越高的地方越容易被非农用地扩张占用,而农村地区的非农用地扩张则倾向于占用土壤质量较低的土壤资源。

Spatio-temporal Impact of Non-agricultural Land Expansion on Soil Resources in Suzhou City

It is quite controversial on the impact of non-agricultural land sprawl on soil resources in China. One opinion holds that food security has been challenged because non-agricultural land sprawl has caused the dramatic shrinkage of agricultural soil resources; and another opinion thinks the food security can be guaranteed by the implementation of "dynamic balance of total amount of arable land between occupying and supplementing" which can keep total area of agricultural soil resources without decrease. Therefore, based on the 4 phases of Landsat TM images covering the 1984-2003 period and the soil quality map generated from local soil map, this paper examined the spatio-temporal dynamics of non-agricultural land expansion on soil resources in Suzhou city, which is one of the most urbanized cities and also characterized by the most fertile soils. The result indicated that the moderately high quality soil is the most extensively occupied soil resource by non-agricultural land expansion in cantonal Suzhou, being 92.10% of the total occupied area. And then the high quality soil followed by less moderately and low quality soil, being only 1.95% of the total expanded area. Additionally, analysis on the non-agricultural land expansion separately in urban and rural areas revealed that in urban area the soil with higher quality is easier to be occupied for non-agricultural purpose while on the contrary, in rural area the soil with low quality is more inclined to be consumed. For example, the expansion rate of high quality soil increased from 1.58% in 1984 to 3.43% in 2003 and that of low quality decreased from 19.95% in 1984 to 1.50% in 2003 in urban area; and at the same time in rural area, the expansion rate of the high quality soil decreased from 2.57% in 1984 to 1.13% in 2003 and increased from 0.88% in 1984 to 2.07% in 2003.