monitoring the effects of precipitation on vegetation cover changes using remote sensing techniques in 12 years period (case study: semirom isfahan)

because soil moisture condition affects vegetation changes hence, monitoring of drought and vegetation changes are among valuable management tools in these ecosystems. nowadays, satellite images are used as a low-cost and fast method for vegetation study in different scales. vegetation change is assessed using vegetation spectral characteristics. this study aimed to analyze and monitor the vegetation cover changes in 4 rangelands and one forest type site in south of isfahan and southeastern of chaharmahal and bakhtiary province during 1997-2009 ّfield sampling were used for measuring the percentage of canopy cover in all vegetation types using step-point method in radial direction (6000 points per vegetation type). regression analysis technique was used to ensure if vegetation cover can be measured properly using a landsat images from 2009. then ndvi indices were derived from 12 landsat images between 1997 to 2009 (all images were taken from 22th of may to 5th of jun each year) to monitor vegetation changes. according to results, there was significant correlation between ndvi indices and canopy cover in all vegetation types. evaluating the canopy cover changes indicated that the precipitation had various effects on different vegetation types based on their plant form and ecological condition. t