Investigating the Performance of Vegetation Indices for Comparing the Production of Natural Ranges and Plowed and Abandoned Rangelands (Case Study of Chaharmahal and Bakhtiari Province Rangelands)

In recent years, a large part of the plowed rangelands has been abandoned due to the lack of economics, knowing such pastures and estimating plant production can play a significant role in their recovery. . It is usually difficult to investigate the changes in rangeand production due to interference in the access to the field and gathering field data. Considering the importance of determining plant production in the proper management of rangeland ecosystems and also the relationship between plant production and rangeland health, the present study evaluate and compares the efficiency of plant indices for determining production in natural rangelands and abandoned rangelands in three regions of semi-steppe rangelands of Chaharmahal-Boukhtiari province. For this purpose, data on plant production in the field were firstly determined by establishing the representative points in each unit by sampling in a random-systematic manner along the transect and via the 2*2 plots by a double sampling approach. Then, using Landsat 8 in 2014 satellite imagery, the indices of vegetation were calculated in the IDRISI software. This process was evaluated 450 plots in three regions and in abandoned and adjacent natural rangelands. The results of NRVI, CTVI, RATIO, TTVI, and TVI indices with correlation coefficients of 0.703, 0.703, 0.703, 0.703, 0.74 and R2 values of 0.53 have the highest correlation with plant production. The results indicate that the NRVI gives a more accurate estimate of plant production in these areas. The production of Marjan diminished from 353.10 to 137.92 kg and in Sefiddasht decreased from 223.48 to 98.01 kg, and in the rangelands of Hureh from 282.19 to 181.17 kg per hectare per year. In general, it can be concluded that remote sensing is a useful tool for assessing the difference in the production of these rangelands.