Kazem Saedi; Adel Sepehri; Mohammad Pesarakli; Hosein Gharedaghi; Reza Azizinejad
Volume 21, Issue 3 , December 2014, , Pages 518-529
Abstract
In most Iranian rangelands, continuous grazing begins with melting snow and continues until the beginning of snow. This study was conducted to evaluate the effects of continuous grazing system on a number of morphological attributes of Bromus tomentellus and Ferula haussknechtii during 2010-2011 in Saral ...
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In most Iranian rangelands, continuous grazing begins with melting snow and continues until the beginning of snow. This study was conducted to evaluate the effects of continuous grazing system on a number of morphological attributes of Bromus tomentellus and Ferula haussknechtii during 2010-2011 in Saral Rangelands of Kurdistan Province. The 30-year exclosure was selected as control area inside the Saral Research Station. In different growth stages, the morphological attributes including the shortest and longest basal area diameter, the shortest and longest canopy diameter, and the height of 10 plants were measured. The annual yield of 30 plants of each species in each year was clipped and weighed to determine forage consumption intensity. All data were subjected to statistical analysis in a completely randomized design using combined analysis. Mean comparisons were performed using Duncan’s Multiple Range Test. Continuous grazing caused to the increase of basal area diameter and canopy diameter of B. tomentellus significantly; however, the height varied in two studied treatments, depending on the year. The three studied morphological attributes of F. haussknekhtii were affected drastically by continuous grazing. In this species, basal area diameter was more affected by the conditions of the year. In both species, ungrazed plants used seasonable rainfall more efficiently as compared to the grazed plants.
Aazam Khosravi Mashizi; Gholamali Heshmati; Aadel Sepehri; Hossein Azarnivand
Volume 17, Issue 4 , November 2011, , Pages 549-563
Abstract
Considering previous studies which showed no significant relation between the distance from water point and total vegetation cover, in current research plant species were classified based on life forms (shrub, bush, perennial grass, perennial forbs and annual forbs) and palatability classes (I, ...
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Considering previous studies which showed no significant relation between the distance from water point and total vegetation cover, in current research plant species were classified based on life forms (shrub, bush, perennial grass, perennial forbs and annual forbs) and palatability classes (I, P and PI). One way ANOVA was applied to determine the variations with distance from water point 8 main directions. Results showed that 8 main directions had no significant effect on vegetation cover and palatability classes of studied life forms. While life forms and palatability classes had different reactions to grazing according to the distance from water point. As shrubs, bushes, perennial grasses and palatability class I increased and annual forbs and palatability class PI decreased with distance from water point. Perennial forbs and palatability class P had uniform distribution. Using results of Duncan multiple range test a critical area was determined at 400 m distance from water point. In the mentioned critical area, shrubs and bushes showed a decrease in vegetation composition while annual forbs increased. Palatability class I also was eliminated in this area. According to the variations in perennial grasses and palatability classI, very sensitive to grazing, it can be concluded that grazing intensity had been very severe at a distance of 800-1000 m from water point.
Maryam Rezashateri; Aadel Sepehri
Volume 17, Issue 4 , November 2011, , Pages 604-614
Abstract
This research was carried out to study the effect of livestock grazing on dynamics of vegetation patches in rangelands of Incheh Boroun, North Gorgan plain. To achieve this goal, the dynamic parameters including the length of vegetation patches and bare area distances between consecutive vegetation patches ...
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This research was carried out to study the effect of livestock grazing on dynamics of vegetation patches in rangelands of Incheh Boroun, North Gorgan plain. To achieve this goal, the dynamic parameters including the length of vegetation patches and bare area distances between consecutive vegetation patches inside and outside the enclosure were measured. First of all, a random point was selected outside the exclosure as starting point and then 11 transects with 50 meters length were placed in a randomized sequential order. The length of vegetation patches and free vegetation spaces were recorded along each transect. Sampling inside the exclosure was done similarly through setting up six 50-meter transect Results showed significant differences in length of vegetation patches, inter patches and ratio of vegetation patches length to inter patches length in both studied regions. Overgrazing outside the exclosure was considered for this result. Since environmental stresses reveal their impacts through changing the shape, frequency and size of vegetation patches, it seems that studying the length of vegetation patches and inter patches has high accuracy and can be done with relatively less time and costs. In addition, it could well represent dynamic changes of plants in response to environmental stresses and desertification process.
Azam Khosravi Mashizi; Gholamali Heshmati; Adel Sepehri; Hossein Azarnivand
Volume 18, Issue 2 , September 2011, , Pages 244-257
Abstract
Aim of this study was to introduce of the functional threshold by ecological process changes along grazing gradient to determine destroyed area.In order to prove the existence of a threshold, two linear models and three nonlinear models (exponential curve, a piecewise regression and a sigmoid logistic) ...
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Aim of this study was to introduce of the functional threshold by ecological process changes along grazing gradient to determine destroyed area.In order to prove the existence of a threshold, two linear models and three nonlinear models (exponential curve, a piecewise regression and a sigmoid logistic) were fitted on stability, infiltration and nutrient cycling data.Two nonlinear models (exponential curve and a piecewise regression) provided a much better fit to the data than the linear models. It is the evidence of threshold along grazing gradient.Results also showed that ecosystem function descended near the water point that it needs special attention of the managers.The passing of the structural threshold, increase of invasive vegetation and animal trampling were identified as the main factors in the decline of ecosystem function near the water point and occurrence of functional threshold.According to the results, the recognition of the threshold is suggested for rangeland ecosystem because defining the threshold will help land managers to prevent the occurrence of undesirable states and promote for sustainable management of rangeland ecosystems.
Esfandiar Jahantab; Adel Sepehri; Bahareh Hanafi; Zohreh Mirdeilamy
Volume 17, Issue 2 , September 2010, , Pages 292-300
Abstract
The study of plant diversity dynamic on grazed and enclosed rangelands is important in range management. The effect of enclosure was studied on plants diversity dynamics on two range condition sites of Dishmook area in Kohgiluyeh & Buyer Ahmad province. Random-systematic sampling was done in two ...
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The study of plant diversity dynamic on grazed and enclosed rangelands is important in range management. The effect of enclosure was studied on plants diversity dynamics on two range condition sites of Dishmook area in Kohgiluyeh & Buyer Ahmad province. Random-systematic sampling was done in two range sites using 220 (2×2 m2) quadrates along 6 transects with the length of 100 m. Vegetation canopy cover percentage was recorded simultaneously in both range sites. Diversity, richness and evenness were determined by using plant diversity indices (Shannon, Simpson, Berger parker & Mc intash). Results show a higher species richness, evenness and species diversity indices in enclosed rangeland. Statistical T-Student Test showed significant differences between two sites in 5 percent level of probability.
Masumeh Baghani; Adel Sepehry; Fatemeh Fadaiy
Volume 16, Issue 4 , January 2010, , Pages 551-559
Abstract
Diversity is one of the main subjects in ecosystem researches. It is also important in recognition of ecosystem health. Plant diversity or taxonomic diversity is medial level of biodiversity rank system. This research was done to compare Shannon diversity indices in different taxonomic levels. The study ...
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Diversity is one of the main subjects in ecosystem researches. It is also important in recognition of ecosystem health. Plant diversity or taxonomic diversity is medial level of biodiversity rank system. This research was done to compare Shannon diversity indices in different taxonomic levels. The study area was mountain rangelands of Ziarat in south Gorgan, Golestan province. Random quadrates, (1 m2) were used to define plant species list and their canopy cover percentage. Dependency of each plant to family, life form, biological type and vegetative life period were studied. Shannon diversity index was calculated for taxonomic level of species and family as well as life form, biological type and vegetative life period in existed vegetation communities of the study area. Results showed that diversity in species and family level carry the same amount of information thus in these levels different communities can better be compared than other levels of life form, biological type and vegetative life period.
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.