Azam Khosravi Mashizi; Mohsen Sharafatmandrad
Volume 28, Issue 2 , June 2021, , Pages 266-279
Abstract
The complexities of the relationship between biodiversity and human welfare can be simplified by identifying the impact of species diversity on ecosystem function. Since annual production plays an important role in the grazing management and sustainability of rangeland ecosystems, this study examines ...
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The complexities of the relationship between biodiversity and human welfare can be simplified by identifying the impact of species diversity on ecosystem function. Since annual production plays an important role in the grazing management and sustainability of rangeland ecosystems, this study examines the relationship between species diversity and annual production of semi-arid rangelands in Khabar National Park under the hypothesis of ecological nest. The annual production of species in 1×1 square plots was estimated in two rangeland types of Artemisia sieberi and Artemisia sieberi- Stipa barbata using the cutting and weighing method. The results showed that although the two plant types differed significantly in terms of annual production (p < /em> <0.05), but there was no significant difference between the two rangeland types in terms of diversity indicators of Shannon, Simpson, Margalf, Manichae, and uniformity index. Pearson’s correlation analysis showed that annual production had a positive and significant relationship with species diversity indicators in Artemisia sieberi- Stipa barbata type; however, no significant relationship was observed in Artemisia sieberi. Contrary to the hypothesis of the ecological nest, species did not have the same contribution in annual production, and the dominant species of Artemisia aucheri had the highest contribution in production. According to the hypothesis of mass ratio, the diversity of functional traits in the dominant species has led to better success of rangeland type the Artemisia aucheri- Stipa barbata than the Artemisia aucheri in terms of annual production. In general, it is recommended that conserving of the composition of plant communities is more important to protect ecosystem services compared to maintaining the maximum number of species.
Jalil Farzadmehr; Hamed Sangooni; Hamid Rouhani
Volume 26, Issue 1 , June 2019, , Pages 18-28
Abstract
In order to investigate the relationship between the distribution of plant communities and environmental factors in Bidokht area, a physiognomic-floristic approach was used. The appropriate area of sampling plot and sample size were determined by the minimal area method and statistical ...
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In order to investigate the relationship between the distribution of plant communities and environmental factors in Bidokht area, a physiognomic-floristic approach was used. The appropriate area of sampling plot and sample size were determined by the minimal area method and statistical approach, respectively. In each plot, the number of plant species and their canopy cover were determined and vegetation mapping was conducted. In each of the plant communities, six soil profiles were drilled and soil samples (composite) were taken from 0 to 100 cm depth. After transferring to the laboratory, parameters of soil texture, lime, pH, electrical conductivity, organic matter, sulfate, calcium, phosphorus, potassium and nitrogen were measured. Information layers were also provided for altitude, slope and aspect of the study area. In order to determine the factors influencing vegetation distribution, PCA-ORD software was used to analyze the principal components (PCA). The results showed that there was a relationship between the factors studied and distribution of vegetation (four rangeland types). The results of principal component analysis showed that the most important environmental characteristics affecting distribution of plant communities in the region were clay, sand, organic matter, electrical conductivity, and potassium (PCA first axis).
Gholamali Heshmati; Hamid Siroosi; esmaeil sheydaye Karkaj
Volume 24, Issue 4 , January 2018, , Pages 742-756
Abstract
Rangelands as dynamic ecosystems respond to the disturbances such as climatic fluctuations and grazing management patterns. Prediction of spatial trend of these changes could be contributed to management planning and rehabilitation of degraded landscape. In this study, changes ...
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Rangelands as dynamic ecosystems respond to the disturbances such as climatic fluctuations and grazing management patterns. Prediction of spatial trend of these changes could be contributed to management planning and rehabilitation of degraded landscape. In this study, changes in the function of ecosystem, affected by livestock grazing, were investigated along grazing gradient. To this end, in the winter rangelands of Gorgan, functional features of the rangeland ecosystem including: nutrient cycling, infiltration and stability were measured at the set of points along grazing gradient. Measured parameters were analyzed using statistical methods and regression models to determine changes in ecosystem function along grazing gradient. The results showed a significant trend in functional indices along the grazing gradient. Points close to the livestock camp had the minimum value of functional indices while those at the end of the grazing gradient were found to be maximized. Comparison of different regression models using Akaike Information Criterion revealed that, as per infiltration index four-parameter sigmoid model and also for stability and nutrient cycling indices, three-parameter sigmoid model had the lowest AIC value and were the best models to predict functional changes along grazing gradients. The results of this study may be promising as rangeland model input to identify critical areas and can be used to predict management effects on productivity and sustainability of rangeland ecosystems.
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.
Morteza Akbarzadeh; Mohammed Reza Moghadam; Adel Jalili; Mohammad Jafari; Hossein Arzani
Volume 13, Issue 4 , February 2007, , Pages 324-336
Abstract
The pressure of livestock grazing and overall utilization of rangelands have caused vegetation and soil degradation in many natural rangelands of Iran. Grazing prevention is one of the rangelands rehabilitation methods, which is effective in renovation of rangelands. The effect of 24 years of grazing ...
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The pressure of livestock grazing and overall utilization of rangelands have caused vegetation and soil degradation in many natural rangelands of Iran. Grazing prevention is one of the rangelands rehabilitation methods, which is effective in renovation of rangelands. The effect of 24 years of grazing protection were studied on vegetation dynamics of Kuhrang region, in two years growing seasons (2003 and 2004). Parameters from rangelands characteristics were collected and analyzed. Results showed that after 24 years livestock exclusion in Kuhrang, total inside canopy cover was higher than outside (P<0.01). Grasses and forbs were higher inside than outside (P<0.01), but shrubs were not significantly different (P>0.05). Over half of inside canopy cover belonged to decreasers and increasers, which were little or negligible outside of exclosure and 95 percent of outside plant composition belonged to invaders. Most desirable species had greater inside cover than outside(P<0.01). Klucia odoratassima, Scorzonera calyculataand Delphinium cyphoplectrumhad greatest inside canopy cover, than other forbs. More than half of inside and 95 percent of outside cover referred to decreasers and increasers. Approximately 38 and 1.2 % of inside and outside forage production belonged to decreasers and increasers respectively. Regeneration was higher outside of exclosure in Astragalus adscendens, in first year. Litter was higher inside and bare soil outside the exclosure (P<0.01). Inside and outside range condition was good and very poor, respectively.
Morteza Akbarzadeh; Taghgi Mirhaji
Volume 13, Issue 3 , February 2006, , Pages 222-235
Abstract
Study of vegetation changes of ungrazed rangelands is important. It is supposed that ungrazed areas tends toward climax and range condition to be improved. The major portion of our rangelands are laied in arid and semi-arid regions. For that precipitation is the major influential factor on vegetation ...
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Study of vegetation changes of ungrazed rangelands is important. It is supposed that ungrazed areas tends toward climax and range condition to be improved. The major portion of our rangelands are laied in arid and semi-arid regions. For that precipitation is the major influential factor on vegetation changes. In dry years as rainfall decreases, the vegetation cover are damage. This study were conducted on Rudshur rangelands for nine years (1996-2004), with the aim of rainfall variation and ungrazed condition effects on vegetation changes. Plant parameters as canopy cover, density and seedling numbers were estimated on permanent plots each year. A dry period were started in 1997 in the region and continued for five years. Results showed, in a period of nine years, total canopy cover declined 40 percent. Decline of canopy cover varied from 26 to 95 percent for different species. Only canopy cover of the Poa sinaica increased about three times, due to earliest vegetative period in growing season. Decline in canopy cover was greatest in forbs, and grasses had lower decline. Regeneration was high in the rainy years and 81 percent of total seedlings belonged to grasses especially to Stipa hohenackeriana. Density of most species decreased in the study period especially in dry years.