Hossein Arzani; Zeinolabedin Hosseini; Khosro Mirakhorlou
Volume 21, Issue 1 , June 2014, , Pages 24-31
Abstract
This study was aimed to assess the applicability of LANDSAT ETM+ satellite images for estimating vegetation production and cover. The images were digitized using topographic maps and geometrized in 1:25000 scales. Required processes such as spectral ratio measurement and vegetation indices were applied ...
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This study was aimed to assess the applicability of LANDSAT ETM+ satellite images for estimating vegetation production and cover. The images were digitized using topographic maps and geometrized in 1:25000 scales. Required processes such as spectral ratio measurement and vegetation indices were applied on the images. Collection was carried out for vegetation cover and production in various vegetation types in homogeneous units. Sampling points' locations were recorded with GPS. Sampling method was random-systematic in such a way that in each unit, a circle with 20 meters radius was considered. One and 9 sampling plots were placed on the centre and on the perimeter, respectively. The plot size was 1m * 1m. In each plot, vegetation percentage was estimated and the production was calculated using double sampling method. Then, DN values for each sampling unit (9 pixels for one unit) were elicited in respect to primary bands' images, vegetation indices and spectral ratios. Correlation and regression analyses between geo-information and satellite information (Digital numbers) were carried out. Results revealed that 7th and 5th Bands and IR1, MIRV2 and VNIR2 indices had a significant correlation with production and given parameter could be estimated through regression models. Likewise, RA, IR1 and TVI indices had a significant correlation with vegetation percentage and this parameter could be estimated through regression models.
Tayebeh Sohrabi; GHolamreza Zehtabian
Volume 19, Issue 1 , June 2012, , Pages 17-31
Abstract
Iran with its special geographical position mainly has an arid and semi-arid climate. The average annual rainfall in Iran is about 240 mm equivalent to one-fourth of the world average rainfall. In addition, irregular spatial and temporal distribution of rainfall has caused problems in natural resources ...
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Iran with its special geographical position mainly has an arid and semi-arid climate. The average annual rainfall in Iran is about 240 mm equivalent to one-fourth of the world average rainfall. In addition, irregular spatial and temporal distribution of rainfall has caused problems in natural resources and agriculture and annually huge amount of our water and soil resources are degraded. Since the advent of the farming activities until the present, human needs have been based upon farming activities. Considering the growing population and the social and economic developments, most of rangelands have been subject to rainfed cultivation. Therefore, to prevent further degradation of soil in these regions research should be conducted on agricultural lands and the exploitation methods. For this reason, Taleghan was selected as the study area. Map of the area, including soil maps, land types and the current land use were produced by GIS. After determining the main treatments, soil samples were taken in every part of the area and in agricultural area and soil factors were measured within two groups of soil improvement factors including nitrogen, phosphorus, potassium, humus and lime and soil degradation factors including acidity, sodium adsorption ratio (SAR) and salinity in two depths of 0-10 and >10 cm. These factors were studied in a split-plot design. The results showed significant differences among treatments. According to the results of soil improvement and degradation factors, orchards and rangelands are in an ideal condition and monoculture treatment decreases the performance of the products.
Hosein Arzani; Khosro Mirakhorlou; Zeinalabedin Hosseini
Volume 16, Issue 2 , December 2009, , Pages 150-160
Abstract
Range management needs to accessing data by fast and suitable methods for planning. Satellite data and geographic information systems (GIS) can be used for planning and integrating field and remotely sensed data. Landuse map is one of the most important information in range management plans. This requires ...
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Range management needs to accessing data by fast and suitable methods for planning. Satellite data and geographic information systems (GIS) can be used for planning and integrating field and remotely sensed data. Landuse map is one of the most important information in range management plans. This requires overlaying, retrieve and analysis detailed information about the rangelands in GIS. Land use map provided using Landsat7 ETM data (15 Apr. 2004) for the study area (middle catchment’s of Taleghan) in the Tehran province. Based on histogram of bands and statistical analysis, bands 4, 3, 2 were selected for color composite in unsupervised classification method. We identified 4 classes land use type of study area in the fieldwork. Ground data was collected using systematic with random start point, from 86 plots (250*250m), using unsupervised map as a primary map. Overall, with combining the ETM data and the field data using supervised classification method, boundary of the landuse types were put in four classes (Rangeland, Farm land, Dry farming and Bare soil). The classification accuracy assessment showed that the overall accuracy 70.64 percent and accuracy rates of the rangeland, farm land, rain fed carping and bare soil were 81, 54, 61, and 81 percent, respectively. So it is possible to use Landsat 7 ETM+ data for landuse mapping which is essential in range management and range suitability classification.
Hosein Arzani; Mahdi Abedi; Ehsan Shahriyari; Mahdi Ghorbani
Volume 14, Issue 1 , January 2007, , Pages 68-79
Abstract
Management activities like grazing intensity and land cultivation effects rangelands characteristic. For sustainable utilization of rangeland, information of changes is required. Soil surface indicators and functional attributes help to judging about management impact. So for investigation on these activities ...
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Management activities like grazing intensity and land cultivation effects rangelands characteristic. For sustainable utilization of rangeland, information of changes is required. Soil surface indicators and functional attributes help to judging about management impact. So for investigation on these activities effects in semi arid rangeland, one vegetation community was selected in Taleghan region. Five cases including: three grazing intensities (heavy, moderate and low), recently cultivated and relict areas that were cultivated in last two decades were assessed. Landscape function analysis (LFA) method was used to evaluate management effects on soil surface characteristics and rangeland functional attributes. In this method for determination of three functional attributes of stability, infiltration and nutrient cycle, 11 soil surface indicators were considered. They are soil surface cover (soil protection from erosion), perennial canopy/basal cover, litter (cover, origin, degree of decomposition), cryptogam cover, crust brokenness, type and severity of erosion, deposited material, soil surface roughness, soil surface resistance to distribution, slake test (soil stability test) and texture. Based on the results, land cultivation reduced functional attributes. By increasing grazing intensity, palatable species are eliminated and in heavy grazing area the dominated vegetation cover are annuals. Vegetation and soil surface layer degradation increased soil erosion, created gully and reduced functional attributes. In relict area because of re-establishing homogenous annuals, soil indicators and functional attribute were improved.
Hosein Arzani; Mahdi Abedi
Volume 13, Issue 2 , February 2006, , Pages 145-161
Abstract
Rangeland as a dynamic ecosystem changes by accruing abundance and if cross the rangeland health threshold may be disturbed. By determination rangeland health attributes, we could judge about management practices effects. In this research for determination three attributes (soil and site stability, hydrologic ...
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Rangeland as a dynamic ecosystem changes by accruing abundance and if cross the rangeland health threshold may be disturbed. By determination rangeland health attributes, we could judge about management practices effects. In this research for determination three attributes (soil and site stability, hydrologic function and biotic integrity) , seventeen indicators used include rill, water flow pattern, pedestals and terracettes, bare ground, gullies, wind scour and depositional area, litter movement, soil resistance to erosion, soil surface loss or degradation, plant composition, soil compaction, plant functional/structural groups, plant mortality, litter amount, annual production, invasive plant and reproductive capability. This method was conducted in six steps. to test this new concept in arid and semi arid zone , thus by using vegetation and soil studies in Orazan (Taleghan) region and Zarand Saveh, selected five treatment included: three grazing intensity and two cultured area and then modified indicators table categorized under three ecosystem attributes in five classes. Because of grazing and cultured treatment rangeland health attributes reduced and showed significant differences by references area. Most treatment crossed the rangeland health threshold. By increasing grazing intensity stractural plant characterestics and soil characteristic beetwin plants disturbed.inreliced cultivated area soil stability and hydrologic function attributes modified but plants health attribute in comperation with references area have a little change. Results showed that soil surface resistance decrease and water flow pattern degradation are the most important causes in rangeland health decrease.