应用高分辨率卫星影像监测退耕地植被的覆盖度

利用QuickBird高分辨率影像,根据QuickBird影像自身特点,改进已有像元二分模型2个参数的估算方法,建立用NDVI归一化植被指数定量估算植被覆盖度的模型,并将该模型应用到退耕地中.结果表明:利用QuickBird影像监测退耕地的植被覆盖度受到退耕苗木树冠大小的限制,树龄小于1年的树木监测效果不佳;树龄大于2.5年的树木监测效果较好,精度可达83%以上,表明用此改进模型对2.5年以上退耕地进行植被覆盖度监测是可行的.

Monitoring Vegetation Coverage Degree of Forestland Converted from Cropland by Applying High Resolution Satellite Image

With high resolution QuickBird image, based on the analysis of the current methods of measuring vegetation coverage degree(f-c),this paper has developed the dimidiate pixel model for quantifying vegetation fraction from normalized difference vegetation index (NDVI). In the improved model, f-c was calculated by the formula: f-c=(NDVI-NDVI- soil )/(NDVI- veg -NDVI- soil ), where NDVI- soil and NDVI- veg represent the NDVI value of pure pixel of barren soil and vegetation, respectively. Using this model to monitor land, the results showed that the monitor effect for vegetation coverage degree of forest land converted from cropland was limited by the size of crown of a tree. It was not good for the small trees whose age were not more than 1 year, but it was good for these trees whose age were more than 2.5 years, of which the average estimated accuracy was more than 83% in the study region. So it will be feasible to use this improved model to monitor vegetation coverage degree of forestland converted from cropland (tree age is more than 2.5 years) from QuickBird data.