The effect of land use and its change on ecological risk in the Lancang River watershed of Yunnan Province at the landscape scale
云南澜沧江流域土地利用及其变化对景观生态风险的影响

GIS spatial analysis was employed to quantitatively study the change of land use in the Laneang River watershed and the transformation of the landscape. TM remote sensing images from 1980, 1992 and 2000 were interpreted algebraically. The assessment quota comprising a landscape disturbance index and a land use sensitivity index, was established on the base of land use change to analyze the temporal and spatial dynamics of ecological risk to landscapes in this region. The results show that the environment has been increasingly disturbed by human activities since 1992 and the transformation rates are comparatively among farmland, forestland and grassland. The changes of land use structure can strongly influence the temporal and spatial distribution of ecological risk. The ecological risk ahove middle level appears in mid-and downstream and becomes significant from southeast to northwest, increasing dramatically in the areas with high risk index. Due to the varied terrain and topography, the difference of ecological risk to the landscape was significant, showing a 7.5 km auto-correlation range. The ecological risk to landscapes in this region is increasing. Ecological protection and construction should he strengthened in the areas with intermediate ecological risk, so as to promote the sustainable development of the ecological environment and the social economy in the Lancang River watershed.