Document Type : Research Paper
Authors
1
Faculty Member, Department of Physical Geography, Faculty of Social Sciences, University of Mohaghegh Ardabili, Ardabil, Iran
2
Department of Physical Geography, Faculty of Social Sciences, University of Mohaghegh Ardabili, Ardabil, Iran
10.22034/gp.2025.66417.3380
Abstract
Vegetation, as one of the living components of ecosystems, is adaptive and has an important effect on most ecosystem processes that are strongly influenced by climatic events, including drought. In the present study, the conditions of vegetation changes in relation to the Standard Precipitation Index Drought (SPI) and the Percent of Normal Precipitation Index (PNPI) were investigated for selected stations in Ardabil province (Ardabil, Khalkhal, Parsabad, and Meshkinshahr) based on 21-year precipitation statistics (2001-2021). And MODIS sensor data was used to prepare the Normalized Difference Vegetation Index (NDVI) to examine vegetation changes on the Google Earth Engine platform. The relationship between drought indicators and vegetation index was analyzed using the Pearson correlation method. Based on the results of the correlation coefficients, the highest correlation between the SPI drought index and NDVI exists at the Parsabad station, which is significant at the 0.01 confidence level, and the lowest correlation is in accordance with the PNPI index at the Khalkhal station. The results of the zoning of the maps showed that based on the calculated SPI and PNPI indices, in the years 2017 and 2021, the drought event occurred with greater intensity than in the other periods under study. Zonal vegetation maps indicate a decrease in the extent of vegetation cover during the years 2006, 2008, 2013, 2017, and 2021 compared to other years, and at all stations, vegetation cover was in more favorable conditions during the months of Apr and May of the study period. In fact, changes in vegetation cover are a function of changes in drought indices, which indicates that vegetation cover is affected by precipitation fluctuations. Based on the findings of the present study, Based on the findings of the present study, it is concluded that vegetation changes have a direct relationship with drought severity.
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