Analysis of vegetation changes related to desert landforms in the northern Isfahan province

This research aims to analyze vegetation changes in desert landforms in the northern region of Isfahan province using Landsat images 5 and 8, specifically TM5 and OLI-TIRS sensors, from 1987 to 2020. For this purpose, 200 images were extracted during the 27 warm months, from June 1 to the end of August. After performing the necessary pre-processing on the images that cover the study region, the landforms were classified using the Topographic Position Index (TPI). Subsequently, the NDVI index was analyzed. The results showed that the pattern of vegetation changes from mountainous areas to lowlands is downward. The analysis of the vegetation index on different landforms, as extracted from the TPI, revealed that the unit of mountains and heights exhibited the highest values, while flat plains such as playas, mud, and clay pans had the lowest values. In general, NDVI values have a decreasing trend from mountain landforms to playas, mud, and clay pans. A significant decrease in NDVI is evident at an altitude of 1400 m (middle pediments). NDVI values increase in mountainous landforms (elevations above 1400 m). On slopes greater than 65° (high stony and rocky lands), the decreasing trend of NDVI has intensified. The NDVI index illustrates four phases of change. The fourth phase, which spanned from 2014 to 2020, exhibited a decreasing trend. During this period, the area covered by this index decreased from 34,380 km² to 34,200 km². The spatial changes of the NDVI index in 2030 indicate that the elevations from Karkas to Marshenan and the areas between Kashan and Ardestan will experience critical conditions. This issue requires the special attention of relevant officials and executives in this field.