Monitoring land use dynamics for ecological degradation assessment in the rim zone of North China using MODIS and Land TM data

摘要

Within North China there is a special rim zone characterized with a mixture of crop farming and herd grazing. Due to intensive land use for cropping and grazing, natural ecosystems in this semi-arid zone have been seriously destroyed in the past decades. Several strong sandstorms in recent years swept through the zone to invade into Beijing the capital of China and other big cities in North China. It has been commonly agreed that the sandstorms are the direct results of landscape ecological destroy in Northwest China, Inner Mongolia and Mongolia Plateau. The ecological degradation and desertification are the core issues concerned from both inside and outside China especially Japan and Korea. In order to monitor the ecosystem development and its dynamics in the zone and in the Northwest China Plateau for possible programs of environmental improvement, many academic efforts have been on the way toward the zone. The current study at our lab is part of the efforts in China. The objective of the study is to monitor the land use changes in last twenty years in the rim zone. Arclnfo GIS has been used as tool to establish a spatial database for the social-economic and natural conditions of the zone. Remote sensing (RS) data especially MODIS and Land TM images have been used for land use mapping. Integrating GIS with RS techniques., we analyze the land use dynamics of the zone, which has above 200 counties spreading in Qinghai, Gansu. Shaanxi. Shanxi, Hebei. Inner Mongolia.. Liaoning. Jilin, and Heilongjiang provinces. The zone can be divided into three sub-regions for detailed examination: the east, the middle and the west. The result indicates that farmland in the zone expands 3.12% from 1985 to 2000. while rangeland as a contrast reduces 3.44% during the period. On the other hand, the occupied area of settlements (villages and towns) increases up to 11.61%. All these imply that intensive anthropogenic activities have been the forces driving the landscape ecosystem in the zone to change dramatically in the recent decades. It is very urgent to administrate crop farming and herd grazing for a sustainable development in the zone where ecosystem has been very fragile.