Land use dynamics and landscape change pattern in Hetao irrigation district, Inner Mongolia, China

摘要

This study analyzed spatial and temporal changes in land use in an irrigation district covering an area of 1.7 million ha in Northern China by GIS analyses and also investigated changes in landscape pattern using the landscape structure analysis program FRAGSTATS over the study period from 1986 to 2000. The decreases in farmland and the increases in grassland area mainly resulted from the policy of grain for green and converting slope farmland into pasture from China government. In spite of the efforts to conserve the fragile ecosystem, the land degradation, including soil salinization and grassland degradation, was spreading rapidly. The area of alkali-saline land increased by 22493 ha and about 50555 ha of dense grassland degraded into mid-density grassland. In terms of landscape fragmentation, both farmland and dense grassland showed the tendency of increased fragmentation. Both adverse natural conditions and human activities are responsible for the land degradation expansion in Hetao irrigation district, but the root causes are increasing population pressure and irrational human activities, such as flooding irrigation method and over-grazing. To prevent land degradation from spreading, population control and improvement of the management are prerequisite approaches.