Investigating the effect of long-term exclosure in a semi-arid experimental watershed on canopy cover of vegetation

This research investigated the effect of long-term excluding livestock as a measure of vegetation cover management in the Kakhk experimental watershed in northeast Iran. For this purpose, the normalized difference in vegetation index was investigated in two grazed and ungrazed sub-catchments from 1991 to 1995 and 2015 to 2019. The results of statistical comparisons showed only in the ungrazed sub-catchment, the mean values of the NDVI in the second period are significantly higher than in the first period. Based on the results, the mean NDVI in the ungrazed sub-catchment has increased from 0.103 in the first period to 0.163 in the second period, whereas, in the grazed sub-catchment it has decreased from 0.152 in the first period to 0.139 in the second period. The survey of temperature data and NDVI showed the growth period of plants in the second period started faster due to higher temperatures in March and April. The results demonstrated the ability of remote sensing to investigate the effects of exclosure to rehabilitate and restore the vegetation cover in watershed management. Also, the results showed the possibility of long-term use of the rangeland without vegetation destruction if the grazing period is managed. Therefore, grazing in the long-term cannot decrease the vegetation cover by correct grazing management. Therefore, the long-term exclosure will not be significant without the application of vegetation restoration methods in watershed management. Also, remote sensing images are capable to investigate the effects of biological measures in watershed management projects.