Aezam Khosravi Mashizi; Gholamali Heshmati; Najmeh Faryabi
Volume 21, Issue 4 , March 2015, , Pages 571-579
Abstract
Negative and positive interactions among plants have important role for species coexistence and community diversity. The strength and direction of the interaction effect may change with environmental disturbances such as grazing and fire. This study was aimed to evaluate the effects of environmental ...
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Negative and positive interactions among plants have important role for species coexistence and community diversity. The strength and direction of the interaction effect may change with environmental disturbances such as grazing and fire. This study was aimed to evaluate the effects of environmental disturbances such as fire and grazing on interactions between shrubs and herbs in rangelands of Goghar Bafte. Hence, beneath 20 dominant species of Artemisia aucheri and 20 open patches, a quadrate of 20 cm×20 cm was plotted and the variation in the biomass, richness and vegetation cover of herbs were measured in regions under exclosure, fire and grazing. Results showed that biomass and vegetation cover of herbs were increased by shrub presence because of positive interaction between shrubs and herbs inside exclosure. Although the facility of shrubs was reduced by grazing and fire, its rate was not equal in both places. Under grazing, interaction between shrubs and herbs remained positive but shrubs were severely damaged by fire and the interaction between species altered from positive to negative. The overall conclusion is that fire plays a more important role in changing the interaction between shrubs and herbs.
seyed hamidreza habibian; gholamali heshmati
Volume 22, Issue 4 , March 2015, , Pages 673-682
Abstract
Different grazing intensities will cause substantial changes in ecosystem function. In order to evaluate the effectiveness of existing management, monitoring of ecosystem structure and function is essential. This research was aimed to investigate the effects of different grazing intensities on surface ...
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Different grazing intensities will cause substantial changes in ecosystem function. In order to evaluate the effectiveness of existing management, monitoring of ecosystem structure and function is essential. This research was aimed to investigate the effects of different grazing intensities on surface indices and soil quality properties in the semi-arid rangelands of Cheshmeh-Anjir, Fars Province. For this purpose, three sites including under exclosure, light and heavy grazing were studied. Landscape Function Analysis (LFA) method was used to investigate the changes among the study sites. One-way ANOVA and Duncan's multiple range test were used for data analysis in SPSS statistical software. According to the results, soil surface indices showed significant differences among the study sites at p<0.05, so that the values of indices were decreased by increasing grazing intensity. Moreover, ecosystem function properties, including stability, infiltration, and nutrient cycling varied by applying different grazing intensities, so that the exclosure site and heavy grazing site showed the best and worst conditions, respectively. Overall, our results clearly showed that the values of functional indices were decreased in the study area by increasing grazing intensity.
Mohsen Sherafatmandrad; Gholamali Heshmati; Mohammadrahim Forouzeh; Hosein Badripour
Volume 21, Issue 3 , December 2014, , Pages 447-454
Abstract
Measurements of production and utilization of key range plant species are of utmost important tools for making range management decisions specially for stocking rate determination. A study was conducted to examine the relationships of production and utilization of Agropyron cristatum and Stipa barbata, ...
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Measurements of production and utilization of key range plant species are of utmost important tools for making range management decisions specially for stocking rate determination. A study was conducted to examine the relationships of production and utilization of Agropyron cristatum and Stipa barbata, as key grasses in Chaharbagh region of Golestan province, with some dimensional parameters. For this purpose, plants height, basal diameter and canopy diameter and their dry weights were measured. Primarily, correlation matrices and Pearson correlation coefficient were used to assess the relationships of these three dimensional variables with production. The three variables were then evaluated for predicting production by using best subset and stepwise regression approaches. Utilization was assessed based on percentage of height removed in relation to percentage weight removed. Results showed that basal and canopy diameters could usefully predict the production of the two grasses. Finally, because of subjectivity of canopy diameter measurements and its weak role in explaining production variations, just basal diameter was considered in models, having linear relationship with production and the coefficient of determinations were calculated to be 72.4 and 71 for A. cristatum and S. barbata, respectively. Therefore, dimension analysis is an appropriate approach to estimate the production and utilization of range key grasses.
Mozhgan sadat Azimi; Gholam Ali Heshmati; Mehdi Farahpour; Abdolreza Bahremand
Volume 21, Issue 2 , August 2014, , Pages 336-346
Abstract
Sagebrush rangelands in Iran with 39.71 million hectares include more than 46% of the total rangelands, and are recognized as an important and dominant rangeland species in Iran-Turan flora. These lands are often associated with grazing of livestock and wildlife. To determine how to better manage ...
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Sagebrush rangelands in Iran with 39.71 million hectares include more than 46% of the total rangelands, and are recognized as an important and dominant rangeland species in Iran-Turan flora. These lands are often associated with grazing of livestock and wildlife. To determine how to better manage this important resource, a rangeland-livestock model was tested in the Hablerud river basin located in Tehran and Semnan Provinces of Iran using the Soil and Water Assessment Tool (SWAT). With regard to climate variation, this watershed consists of three ecological zones: semi-steppe, steppe, and desert. Calibration and validation of model were tested with the Sequential Uncertainty Fitting Program (SUFI-2). Results showed that observed data of forage production were inside or quite close to the predicted bands in three zones. Also, based on the model results, simulated forage production varied from 0.35 to 0.5, 0.15 to 0.26, and 0.033 and 0.1 ton ha-1 in semi-steppe, steppe, and desert, respectively. Sensitive analysis showed that whatever we move from semi steppe to desert, the number of sensitive parameters increases and water and soil parameters becomes more sensitive in forage production.
Razieh Mohammadi; Kamaladdin Naseri; Gholamali Heshmati
Volume 21, Issue 1 , June 2014, , Pages 119-127
Abstract
This study was conducted to investigate the effects of Haloxylon aphyllum plantation on natural plant communities and soil properties of Abbas-Abad area in Khorasan Razavi Province. For this purpose, Haloxylon plantation and control areas were selected to compare with each other. In each area, fifty- ...
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This study was conducted to investigate the effects of Haloxylon aphyllum plantation on natural plant communities and soil properties of Abbas-Abad area in Khorasan Razavi Province. For this purpose, Haloxylon plantation and control areas were selected to compare with each other. In each area, fifty- meter transects were located by random-systematic method. Measurements were done by point sampling method. Eighteen soil samples were collected from Haloxylon plantation and control areas to determine EC and pH values in the laboratory. Data were analyzed by t-test. According to the results, although higher species diversity was significant in Haloxylon plantation area (P<0/05), Haloxylon caused the replacement of non-native communities, so that only 64.28% of species composition in Haloxylon plantation area was similar to the control area. On the other hand, higher soil pH and EC in Haloxylon plantation area was significant (P<0/01) and probably in the long term, Haloxylon causes the salinity and alkalinity of the soil surface.
Azam Khosravi Mashizi; Gholamali Heshmati
Volume 18, Issue 4 , September 2012, , Pages 547-557
Abstract
To identify destroyed area and to introduce a piospher, pattern of vegetation composition was considered at different distances from a water point.Therefore in 113 plots, species density and vegetation cover were evaluated.To identify the patterns of vegetation composition, Clustering analysis was applied ...
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To identify destroyed area and to introduce a piospher, pattern of vegetation composition was considered at different distances from a water point.Therefore in 113 plots, species density and vegetation cover were evaluated.To identify the patterns of vegetation composition, Clustering analysis was applied on species density and vegetation cover and three distinct groups of vegetation composition were obtained. ANOVA analysis showed that three groups were different (p<0/01). By using DCA, relations between groups and species were evaluated. Result showed that there was a piospher on 300 m from water point. In this zone, vegetation composition extremely changed due to heavy grazing and palatable species were replaced by annual or perennial unpalatable species but with distance from water point, perennial and palatable species increased. Study of relations between vegetation compositions (was obtained by plant functional types) and grazing intensity showed that in addition of quantitative methods, qualitative methods such as vegetation composition and plant functional types could be an appropriate method to determine ecosystem condition in shrublands.
Zohreh Mirdeylami; Gholam Ali Heshmati; Hosein Barani; Yalda Hematzadeh
Volume 19, Issue 2 , September 2012, , Pages 333-343
Abstract
Recognition of ecological factors affecting the establishment and distribution of plants is necessary and the use of multivariate analysis could be useful to achieve this purpose. In the current research, relationship among the most effective environmental parameters on distribution and establishment ...
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Recognition of ecological factors affecting the establishment and distribution of plants is necessary and the use of multivariate analysis could be useful to achieve this purpose. In the current research, relationship among the most effective environmental parameters on distribution and establishment of vegetation types of Kachik Watershed was studied by multivariate analysis method. After providing land unit maps, density and canopy cover percentage were measured in reference areas of each land unit. Random-systematic method was used and sampling was performed on 53 quadrates established on 19 transects with intervals of 150 m. Soil samples were taken from the depth of 0-30 cm and pH, EC and percentage of clay, silt and sand were measured. Six separate ecological groups were identified by cluster analysis. Results of principal component analysis revealed that aspect, slope, pH, EC, soil texture and Ca had the most effect on distribution of ecological groups with correlation coefficients of 0.98, 0.96, 0.93, 0.89, 0.82 and 0.81, respectively.
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.
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.
Zeid Ahmadi; Gholam ali Heshmati; Mahdi Abedi
Volume 16, Issue 1 , December 2009, , Pages 55-65
Abstract
Rangeland managers must have knowledge about ecological factors that determine the rangeland health. In this study used Landscape Function Analysis method for assessment the rangeland health in three landscapes. Sampling done in the three transects of 50 meters length and eleven soil parameters was measured ...
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Rangeland managers must have knowledge about ecological factors that determine the rangeland health. In this study used Landscape Function Analysis method for assessment the rangeland health in three landscapes. Sampling done in the three transects of 50 meters length and eleven soil parameters was measured on them. Three attribute functions including infiltration; stability and nutrition recycle measured in three landscapes: 1- complete exclusive rangeland, 2-semi exclusive rangeland, 3- freed exclusive rangeland and contiguous zones of them. Results show that there was significant difference between three attribute functions in three landscapes. Also three attribute functions were higher in three landscapes than contiguous zones. Three attribute functions were higher in "patches" than "inter patches". According to above results, improvement operations controlled the livestock grazing of rangeland and health indices were promoted in the complete exclusive rangeland.
Payman Lotfi anari; Gholamali Heshmati
Volume 16, Issue 3 , December 2009, , Pages 386-400
Abstract
Application of new rangeland ecosystems monitoring methods is essential for ecological studies. LFA principles and soil surface assessment parameters are based on ecological conditions of Australia. The aim of this study was calibration of LFA method for an arid rangeland ecosystem located in central ...
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Application of new rangeland ecosystems monitoring methods is essential for ecological studies. LFA principles and soil surface assessment parameters are based on ecological conditions of Australia. The aim of this study was calibration of LFA method for an arid rangeland ecosystem located in central part of Iran with 188 mm annual mean precipitation. In LFA 11 soil surface parameters are ranked to determine soil surface indices (infiltration, stability and nutrient cycling of soil). To calibrate LFA, soil surface assessment had been done with 10 replications. Then sensitivity analysis of 11 parameters had been done. Soil texture and kind of erosion and its severity parameters with lowest sensitivity had been deleted from LFA and available pebble in soil surface added to LFA as a new parameter (Calibrated LFA). Verification of LFA and calibrated LFA soil surface indices had been done by regressing them against field and experimental measurements and the results compared together. Results indicate that LFA and calibrated LFA soil surface indices are in moderately verified class (R: 0.4-0.6) and strongly verified class (R>0.6) respectively. This represents more efficiency of CLFA revised method in comparison with LFA method for using in the study area and similar areas.
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.