Nazila Tayeb Nejad; Younes Asri; Manije Pakravan; mohammadreza najibzadeh
Volume 24, Issue 2 , July 2017, , Pages 392-403
Abstract
Acantholimon gilliatii, Astragalus aharicusand A. neo-mobayenii are the endemic species with one population in East Azarbaijan. Previous observations of researchers have shown that survival of these species at risk and their distribution is being limited. In this study, topographic, climatic and soil ...
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Acantholimon gilliatii, Astragalus aharicusand A. neo-mobayenii are the endemic species with one population in East Azarbaijan. Previous observations of researchers have shown that survival of these species at risk and their distribution is being limited. In this study, topographic, climatic and soil characteristics were investigated in habitats of these species. Also, coverage, height density and phenology of the study species were determined by using 10 plots in each area with random method during 2013 and 2014. The habitat of A. gilliatii is very limited in the southern slopes of the Mishodagh Mountain, with a slope of 15-30 %, an altitude of 2010 m, loam-sandy soil and cold semi-humid climate. Also, the habitat of A. aharicus is very limited in the southwestern slopes of the Kasabeh Mountain, with a slope of more than 60 %, an altitude of 1750 m, loam-clay calcareous soil and semi-arid climate. The habitat of A. neo-mobayenii is patchy in the northern slopes of the Mishodagh Mountain, with a slope of 60-70 %, an altitude of 1800 m, loam-sandy soil and cold semi-humid climate. It seems that droughts and heavy livestock grazing have resulted in limiting the populations of the study species. Therefore, adopting measures such as protecting the habitat of these species, investigation of the factors affecting the regeneration of these plants as well as pest control are essential to avoid the removal of these species from the natural arena.
Mohamad Farahnak Ghazani; Mohamadreza Najibzadeh; Mohamadali Ghahramani
Volume 22, Issue 3 , November 2015, , Pages 537-545
Abstract
In recent years the utilization rate of renewable resources especially the pressure of livestock grazing has increased. Uncontrolled livestock grazing has caused reduction of quantity and quality of forage, therefore, studying the effects of exclosure on vegetation changes is very important. In this ...
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In recent years the utilization rate of renewable resources especially the pressure of livestock grazing has increased. Uncontrolled livestock grazing has caused reduction of quantity and quality of forage, therefore, studying the effects of exclosure on vegetation changes is very important. In this research, the effects of exclosure on vegetation changes of Sahand rangelands were studied during 2001 to 2006. The vegetation changes were investigated inside and outside the exclosure area, using fixed transects. The results showed that total canopy cover and canopy cover of perennial grasses including Agropyrum trichophorum، Bromus tomentellus، Dactylis glomerata and Festuca ovina increased significantly inside the exclosure area (P<0.01). In terms of palatability, class I species increasedsignificantly (P<0.01). Cirsium haussknechtii, one of the important invasive species of the area, decreased significantly inside the exclosure area. There was no significant changes on total canopy cover of outside of the exclosure area. Canopy cover of perennial grasses and perennial forbs decreased (P<0.05) and shrubs canopy cover increased (P<0.01). Class I species decreased and class III species increased in outside of the exclosure area but it was not statistically significant. Canopy cover of Cirsium haussknechtii increased in outside of the exclosure area (P<0.05). No significant changes of soil organic matter were detected inside and outside of the exclosure area during six years.
Mohammad reza Najib zadeh; Adel Sepehri; Gholam ali Heshmati; Ali akbar Rasooli
Volume 15, Issue 2 , January 2008, , Pages 200-214
Abstract
Land degredation is a common phenomenon of arid rangelands. Improper utilization of rangelands out of their potential capability is the main cause of land destruction. To avoid damageing environmental resources, it is necessary to use lands based on their natural potentials. To have both sustainable ...
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Land degredation is a common phenomenon of arid rangelands. Improper utilization of rangelands out of their potential capability is the main cause of land destruction. To avoid damageing environmental resources, it is necessary to use lands based on their natural potentials. To have both sustainable development and optimum utilization, we need to evaluate potential productivity of rangelands baesd on simple models that easly relate measurable environmental parameters to potential herbage productivity of rangelands. In this study our aim is to evaluate ERAMS model to evaluate land capability of Yekkeh Chenar Maraveh tappeh rangelands using GIS. This model includes 4 parameters including: slope, salinity, soil depth and rainfall. To get the final land capability map of the area, digital layers(maps) of those parameters were prepared and intered in the model using overlay functunality of GIS. Cross tabulation was used to asses the degree of agreement between the actual and potential land capability maps produced by ERAMS model. Kappa Index of Agreement value shows an overall agrement of 41% between the actual and potential land capability maps. That means ERAMS model was able to define the potential land capability of the area with 41% accuracy. Result also shows that the highest attained agreement belong to the category of high density vegetation. This model can predict the potential productivity of rangelands with high productivity rate better than those of low productivity as was the case for the study area.. This model is thus recommended to be used for vast and densly vegetatated areas.