Evaluation of the effects of climate change on the mid-elevation pasture vegetation of mountainous areas; A Case Study of the Sablan Mountainside, Iran

Abstract

Abstract The impact of global warming and climate change on vegetation is a significant challenge in the present day. The pastures of the Sablan Mountains, located in Northwestern Iran, in Azerbaijan, are renowned for their richness and pivotal role in supporting the livelihood of residents. Additionally, these meadows serve as an alluring destination for climbers and tourists from around the world, offering a captivating recreational experience In this study, the trends of climate parameter changes and vegetation cover over a period of 17 years (2019–2003) were investigated using meteorological data from two range stations and the NDVI index derived from Landsat satellite images. The Mann-Kendall test was employed to analyze the trends, and the relationship between the simple and multiple linear regression of climate parameters and the NDVI of the entire pasture was examined. Specifically, the analysis focused on pastures at different elevations, including low elevations(2500–1500 m), middle elevations (3500–2500 m), and high elevations (above 3500 m). Additionally, a map illustrating the changes in NDVI over the 17–year period was created. According to the findings, it was observed that among the various climatic parameters examined, only the average temperature in June exhibited a significant increasing trend. The rate of increase was measured at 0.071 degrees Celsius per year, with a significance level of 5 percent Based on the analysis of NDVI trends during the first month of summer, it was observed that the NDVI of the total land use classification of pasture and the mid-elevation pasture land use classification (3500–2500 m) exhibited significant increases at a significance level of 5 percent. Precisely, the NDVI of the total land use classification of pasture showed an annual increase of 0.004, while the mid-elevation pasture land use classification demonstrated an annual increase of 0.006. The simple linear regression analysis revealed a significant direct linear correlation (R) between the NDVI of high-elevation pastures (3500–2500 meters) and the average and maximum temperatures in July: The NDVI exhibited a correlation coefficient of 0.567 with the average temperature and 0.527 with the maximum temperature, both at a significance level of 1 percent. The NDVI of pasture land use exhibited a significant straight simple linear correlation of 0.554 with the average temperature in June, at a significance level of 1 percent. The multiple linear regression analysis revealed that when considering both the average and maximum temperature of the spring as simultaneous predictors, the direct correlation between the NDVI of the 3500–2500 m class of pasture and these parameters increased from 0.567 (in the simple linear model) to 0.727 (in the multiple linear model). The results of this study suggest that the rise in temperature within the pastures of the Sablan Mountains has created favorable circumstances for the growth and expansion of vegetation, particularly in middle elevations.