Investigating the topographic and climatic effects on vegetation using remote sensing and GIS: a case study of Kharestan region, Fars Province, Iran

Abstract

This study seeks to investigate the effect of topographic (slope, elevation, and aspect) and climatic (precipitation and
temperature) factors on vegetation in Kharestan region using remote sensing (RS) and geographic information system
(GIS) techniques. To this aim, therefore, the changes occurred in such vegetation indices as normalized difference index
(NDVI), enhanced vegetation index (EVI), soil-adjusted vegetation index (SAVI), and difference vegetation index (DVI)
between 2008 and 2015 were evaluated, using Landsat ETM7. The findings of the study showed that the highest density
for the NDVI, EVI, SAVI, and DVI could be found at an elevation range of 2000 to 2800 and the lowest density could be
found at elevations lower than 2000 and higher than 2800 m. In addition, the maximum values for the indices at elevation
range of 2050 to 2250 were 0.56, 0.54, 0.4, and 0.25 respectively. Moreover, the highest values for the indices were found
at such aspects as the northeast (64° and 42°) and the north (348°), while the lowest ones were observed at the eastern (74°)
and southwestern (243° and 206°) aspects. As for the density of the vegetation, the maximum mean values for the indices
were found to be located at slope range of 4 and 12°. These findings indicate that lower elevations, shaded sides of the
domains, and gentle slope enjoy appropriate conditions for the growth of vegetation. Furthermore, there was a significant
correlation between the indices, the temperature, and the precipitation (P < 0.01). Considering the aforementioned results,
it could be argued that environmental factors such as elevation, aspect, slope, precipitation, and temperature are among the
main factors, which control the vegetation in the region studied in this research.