Evaluation and mapping of rangelands degradation using Remotely Sensed Data

Abstract

The empirical and scientifically documents prove that misuse of natural resource causes 
 degradation in it. So natural resources conservation is important in approaching sustainable 
 development aims. In current study, Landsat Thematic Mapper images and grazing gradient 
 method have been used to map the extent and degree of rangeland degradation. In during 
 ground-based data measuring, factors such as vegetation cover, litter, plant diversity, bare soil, 
 and stone & gravels were estimated as biophysical indicators of degradation. The next stage, 
 after geometric correction and doing some necessary pre-processing practices on the study 
 area's images; the best and suitable vegetation index has been selected to map rangeland 
 degradation among the Normalized Difference Vegetation Index (NDVI), Soil Adjusted 
 Vegetation Index (SAVI), and Perpendicular Vegetation Index (PVI). Then using suitable 
 vegetation index and distance parameter was produced the rangelands degradation map. The 
 results of ground-based data analysis reveal that there is a significant relation between 
 increasing distance from critical points and plant diversity and also percentage of litter. Also 
 there is significant relation between vegetation cover percent and distance from village, i.e. 
 the vegetation cover percent increases by increasing distance from villages, while it wasn't the 
 same around the stock watering points. The result of analysis about bare soil and distance 
 from critical point was the same to vegetation cover changes manner. Also there wasn't 
 significant relation between stones & gravels index and distance from critical points. The 
 results of image processing show that, NDVI appears to be sensitive to vegetation changes 
 along the grazing gradient and it can be suitable vegetation index to map rangeland 
 degradation. The degradation map shows that there is high degradation around the critical 
 points. These areas need urgent attention for soil conservation. Generally, it shows that the 
 most parts of rangelands in studying area have been degraded. So conservation priorities on 
 degraded rangelands have been recognized based on current degradation.