漓江流域近15年遥感植被覆盖度f_(veg)变化特征

为研究漓江流域近15年植被覆盖度变化情况,以1991、2000、2006年3个时相的TM/ETM+影像为基础,采用基于归一化植被指数(NDVI)的像元二分模型对漓江流域植被覆盖度进行估算,分析了植被覆盖度时空变化特征;结合研究区地质数据,进一步分析地质条件对植被覆盖度的影响。结果表明:①受气候和人类活动的影响,1991—2000年漓江流域植被覆盖度有所增加,表现为高和较高植被覆盖区面积增加,中度、较低和低植被覆盖区面积减少;2000—2006年漓江流域植被覆盖度略有降低,表现为高植被覆盖区面积减少,较高和中度植被覆盖区增加,较低和低植被覆盖区面积减少;②由于地质条件的影响,非岩溶区的平均植被覆盖度高于岩溶区,两者的变化趋势与流域整体变化基本一致;③从空间分布上看,1991—2006年漓江流域植被覆盖度的变化较显著。

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 during 1991 -2006.