Vegetation coverage changes in the Lijiang river basin based on remote sensing in recent 15 years

In order to study the vegetation coverage changes of the Lijiang river basin in 15 years,with Landsat TM / ETM + data of 1991,2000 and 2006 as data sources,by dimidiate pixel model based on NDVI,the vegetation coverage of the Lijiang river basin is evaluated and characteristics of temporal-spatial changes are analyzed in past 15 years.From the geological data in the study area,influences of the geological conditions to vegetation coverage are analyzed.Results are described in three aspects:①Because of the climate and human activities,the vegetation coverage in the Lijiang river basin got a rise in 1991- 2000.The area of high and higher vegetation coverage districts increased,while that of middle,low and lower vegetation coverage districts decreased.Vegetation coverage got a decrease in 2000- 2006.The area of high vegetation coverage districts decreased,higher and middle vegetation coverage districts increased,while that low and lower vegetation coverage districts decreased;②Due to the influence of the geological conditions,the average vegetation coverage in non-karst area is higher than that in karst area,but the overall trend consistent with changes in the Lijiang river basin;③Spatial distribution of vegetation coverage changes are significant in the Lijiang river basin during1991- 2006.