Abstract:

Huge press on natural resources and environment in China requires the study of the regional land quality pertinent to land degradation. Land use, which is exhibited as patches in space, has a close relationship with land quality. The research of the relationship between land use and land quality at patch scale can improve our under standing of the effects land use changes on land quality. The Ministry of Land and Resources implemented “Remote Sensing Monitoring on Land Resources and Eco - environment in Area around Beijng”and“Remote Sensing Monitoring Study for Distribution of Cultivated Farmland and Grain for Green in Typical Regions around Beijing”projects from 2002 to 2004. With the help of the project's achievements, the cultivated farmland changes in Zhangbei County, Hebei province, from 1999 to 2003 were analyzed by using the SPOT2/4 and SPOT5 remote sensing data. The degradation character of changed patches from cultivated land in 1999 to grassland and forest land in 2003, from grassland and forest land in 1999 to cultivated land in 2003 and unchanged cultivated land were analyzed by the application of GIS and statistical methods. The cultivated land decreased by 20229.5ha in 2003 compared to 1999, most of which turned into grassland and forest land, and the main type is the change of farmland to man- made grassland. The most of newly increased cultivated land came from grassland. The area of un- degraded patches in all types from cultivated land to grassland and forest land, except the change from farmland to low- density forest land, are larger than degraded patches, indicating these change types could lead to a higher land quality. The changed patches from forest land to farmland and from grassland to irrigated farmland have an obvious degradation inclination; however, the proportion of changed patches' area and quantities from grassland to farmland, from other land to farmland and from grassland to vegetable land is not large. Compared to un- changed cultivated patches, the area proportion of undegraded patches to total changed patches from farmland to grassland is larger and the quantity proportion is similar; the area and quantity proportion from farmland to grassland is not different largely. Both area and quantity proportions of un- degraded patches from farmland to forest land are larger than those from forest land to farmland. These results indicate the transition from farmland to forest land and grassland can improve the regional land quality.

Key words: land degradation, land quality, land use change, patch scale