Evaluation of the effects of climate variability on vegetation in mountainous rangelands (case study: Sabalan Mountainside in Iran)

The impact of climate change on vegetation growth has become a significant issue in recent years. This study focuses on the effects of climate variability on vegetation cover of rangelands in different elevation zones of the Sabalan Mountain region in northwestern Iran, which plays a vital role in the local economy and ecosystem. The study utilized a combination of climate and rangeland vegetation cover data Normalized Difference Vegetation Index (NDVI) collected over 17 years (2003–2019) from two local weather stations and Landsat satellite imagery. The Mann-Kendall test was used to identify trends, and simple and multiple linear regressions (p<0.05) models were employed to assess the relationship between climate variables and vegetation cover NDVI. The results showed that a significant rise in June average temperatures (0.071°C/year, p<0.05), while vegetation cover showed a notable increase in NDVI during early summer (0.004/year for low-elevation rangelands, 0.006/year for mid-altitude rangelands, p<0.05). A strong positive correlation (r=0.57 for mean and r=0.52 for peak temperature, p<0.01) was found between NDVI in higher-altitude rangelands and July temperatures. The NDVI of rangelands also showed a notable positive correlation of r=0.55 with the average June temperature (p<0.01). Additionally, the multiple regression analysis revealed that the relationship between NDVI and temperature parameters strengthened at mid-altitudes, with an increase in correlation (r=0.73) (p<0.01) when both average and maximum spring temperatures were considered. This research highlights the potential implications of climate change for rangeland management in the region, offering insights for future studies and climate adaptation strategies.