Integration of remote sensing and GIS technology to evaluate grassland ecosystem health in north China

摘要

Grassland in north China faces serious ecological degradation in recent decades. Overgrazing and unsuitable farming over the grassland are believed to be the direct causes leading to such ecological disasters as sand and dust storms in north China. Objective of the study is to integrate remote sensing and GIS technology for evaluation of grassland environmental heath in north China. Methodology used in the study includes ground observation, grassland database establishment, reclamation mapping, and remote sensing image interpretation. Our results indicate that grassland reclamation for agricultural farming is very serious in recent decade in north China. About 15% of grassland has been reclaimed into farmland in the transaction zone of north China in a short period from 1985 to 2000. Most reclaimed farmlands are not suitable for agricultural cropping. In both transaction and pasture zones the areas of unsuitable farmland account for above 20% of total farmland area. Desertification is also very serious in the grassland. 4 of the 6 provinces under study have over half of grassland areas suffering various levels of desertification. Percentage of grassland areas under intensive desertification to the total is high up to 57% in Gansu and over 30% in Inner Mongolia, Oinghai and Ningxia. We classified the grassland into 5 categories according to the degree of desertification. The results show that the categories with slight, moderate and complete desertification mainly concentrate in southern and central Inner Mongolia. This evaluation provides valuable assistances to policy proposals for local administration of farming and grazing activities in the region.