Meisam Aramesh; abbas ali vali; Abolfazl Ranjbar
Volume 29, Issue 2 , July 2022, , Pages 146-160
Abstract
Desertification is a serious ecological, environmental, and socio-economic threat to the world, and there is a pressing need to develop a reasonable and reproducible method to assess it at different scales. Therefore, in the present paper, changes in cover and desertification of Kashan, Aran and Bidgol ...
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Desertification is a serious ecological, environmental, and socio-economic threat to the world, and there is a pressing need to develop a reasonable and reproducible method to assess it at different scales. Therefore, in the present paper, changes in cover and desertification of Kashan, Aran and Bidgol regions in the north of Isfahan were developed using Landsat ETM and OLI data. According to this research, NDVI (Normalized Difference Vegetation Index), TGSI (Topsoil Grain Size Index), and land surface albedo were selected as indicators for representing land surface conditions from vegetation biomass, landscape pattern, and reflection. A Decision Tree (DT) approach was used to assess the land cover change and desertification of the study area from 1995-2020. Temporal changes indicated an increase in NDVI, TGSI, and albedo trends during this period. The spatial distribution of NDVI showed that values greater than 0.5 were observed only in a small part of the west and southwest, while high values of TGSI and albedo occupied a large area of the study area. There was also a correlation between the above three indicators at 95% (R = 0.99). The results also showed that desertification is increasing in the study area, so that the intensity of desertification from 1995 to 2020 in classes without desertification was low, medium, and severe. The high desertification class decreased by 1420.75 square kilometers (13.54%), while severe desertification increased by approximately 1388.8 square kilometers (13.23%). The highest NDVI values were found in the non-desert area and the low desertification class, while the highest TGSI and albedo values were found in the high and severe desertification classes.
Jahan bakhsh Pairanj; Ata... Ebrahimi; Abalfazl Ranjbar; Mohammad Hasan zadeh
Volume 18, Issue 4 , September 2012, , Pages 593-607
Abstract
Evaluation of forage production is an important issue in determining grazing capacity of rangelands. There is no doubt that all forage production in rangelands is not evenly accessible and different factors affect the accessibility of forage. In this research, factors affecting forage availability were ...
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Evaluation of forage production is an important issue in determining grazing capacity of rangelands. There is no doubt that all forage production in rangelands is not evenly accessible and different factors affect the accessibility of forage. In this research, factors affecting forage availability were studied. After a wide literature review, factors of distance from water supplies, density of shrubs, slope and land uses were identified as the main factors preventing forage accessibility. Forage production and shrub density were respectively measured using clip and weighing method in quadrates and distance method. Forage production measurements in representative area were extrapolated to the whole area using IRS satellite images. In this research, 18 vegetation indices were examined as forage production data (independent factor) were regressed against vegetation indices values (dependent factor) using SPSS. Map of forage production was created based on the best fit regression. Then, with adjusting all limiting factors, the map of accessible forage production was created based on the tables. The maps were illustrated and available forage was calculated after implementing adjustment of each factor. Statistical results showed significant differences (p≤0.05) between forage production with considering slope and shrub density and forage production based on all limiting factors of forage accessibility. While distance from water supplies and other land uses had no significant effect on forage production