Spatio-Temporal Changes of Natural Vegetation Disturbance in the Ahle Iman Watershed, Ardabil Province

Abstract

The present study aimed to assess the spatio-temporal changes in the natural vegetation cover of Ahl Iman watershed, Ardabil province. For this purpose, land use maps of the three years (2000, 2010, and 2020) were extracted from Landsat satellite images. Then, seven landscape metrics (patch density, edge density, patch richness, splitting index, contagion index, Euclidean nearest neighbor distance, and mean perimeter–area ratio), Normalized Differential Vegetation Index (NDVI), and road density were calculated. Finally, the Disturbance Index (DI) was calculated by the sum of the values of the criteria multiplied by their weight in the 11 sub-watersheds. The disturbance index (DI) was classified into very low (0-87), low (88-163), medium (164-239), high (240-315), and very high (>316) categories. Results showed DI of 177.77, 95.17, and 135.07 for the three studied years (2000, 2010, and 2020), representing a moderate, low, and low disturbance respectively. There was no significant difference between the three years in terms of disturbance. Further, the eastern and northern parts had higher disturbance indices compared to the southern and central parts of the watershed.