APPLICATION OF ETM+ DATA FOR ESTIMATING RANGELANDS COVER PERCENTAGE (CASE STUDY: CHAMESTAN AREA, IRAN)

The major land cover in Iran is rangeland, so it is not possible to assess the vegetation cover of these vast areas through field work. During the recent years, many researchers have used various satellite data with vegetation indices as a tool to evaluate the rangelands vegetation cover and to estimate the yield and percentage cover. This study was carried out in Chamestan area rangelands (12000ha) in Mazandaran province, Iran. Landsat ETM+ data with acquisition date of 18th July, 2000 were registered to digital topographic maps with scale of 1:25000. Multi spectral bands were registered to TM8 panchromatic band using data fusion method in two ways: “Spectral Response ” and “Hue, Intensity, Saturation (HIS) ” techniques. In addition, 26 vegetation indices were applied to Landsat data as well. Field surveys and available vegetation maps confirmed the limited number of vegetation types that were not exceed to four major vegetation forms at the studied areas. Totally on 40 points, 400 quadrates were placed to estimate vegetation cover. To arrange these quadrates, on each randomly selected point, 10 quadrates each 10m*10 m were placed on perimeter of a supposed circle with 20m radius. This supposed circle covers (3*3) =9 pixels of ETM+ image. Inside of each quadrate the percentage vegetation cover was estimated and the dominant species were recorded. Correlation and stepwise regression analysis were applied to field data and vegetation indices. These indices were the products of the Landsat data bands and the fused bands. The results illustrated that vegetation indices alone did not have enough ability to estimate percentage cover on studied rangelands. But applying of vegetation indices to ETM+ bands along with fused bands, leads to get reliable results on estimating of rangelands percentag