Surveying of the past, present, and future of vegetation changes in the central Alborz ranges in relation to climate change

Acceleration of climate trend change is caused by the swift shift of rangeland conditions that using modern methods of evaluation to them are counted to sustainable management of the rangelands. In order for an investigation of trend change of rangeland vegetation due to climate change, central Alborz rangelands were selected. Normalized Difference Vegetation Index (NDVI) for the period of 30-year (1987-2016) was extracted by Landsat satellite, TM, ETM+, and OLI series. Drought periods were determined using the Standardized Precipitation Index (SPI). The Markov Chain model was used to anticipate the future changes of rangeland vegetation. The results showed that the vegetation cover index’s changes have risen and fallen for three decades in which, despite of increasing for some years 1986 (0.86), 2002 (0.87), 2005 (0.87), and 2015 (0.86); the changes trend was decreasingly for 1995 (0.53), 1998 (0.65), 2000 (0.62), and 2008 (0.61) years, especially for fair to very poor classes. The highest correlation (91.5%) between the SPI and NDVI was shown that severe to moderate drought has taken place along with decreased vegetation periods. Moreover, the Markov Chain model has anticipated a forcible declined change of vegetation cover for 2031 and 2046 periods. Therefore, range management approaches have to prepare itself in order to the gradual increase of temperature, which has destructive effects on vegetation cover, via regulating of grazing capacity and replacing of highly performance livestock in the future.