Hamidreza Mirdavoudi; Vahid Etemad; Mohammadreza Mohajer; Ghavamoddin Zahedi Amiri
Volume 25, Issue 1 , April 2018, , Pages 116-128
Abstract
Grazing is one of the most important factors in providing environmental conditions for change in species composition, structure and function of ecosystems. West oak woodlands of Iran as a valuable ecosystem are not immune from this threat. Therefore, it is essential to study the various ...
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Grazing is one of the most important factors in providing environmental conditions for change in species composition, structure and function of ecosystems. West oak woodlands of Iran as a valuable ecosystem are not immune from this threat. Therefore, it is essential to study the various aspects of this phenomenon in these ecosystems. The aim of this study was to examine the effects of relative grazing intensity on vegetation characteristics in an oak forest dominated by Quercus brantii. The research was conducted in Dalab Park, located in Ilam province, west of Iran. Information of vegetation, soil and other environmental variables were collected from 53 sample plots (16×16 m) using the random sampling method in various disturbances classes. Two-way indicator species analysis was used for classification of the ecological groups. Indicator species analysis was used to determine indicator species in each class and canonical correspondence analysis to identify the relationship between factors and the plant groups studied. The results showed that the grazing as well as soil, topographic factors and the light reaching to the forest floor was identified as the most influential factors on plant composition. Grazing explained the highest percentage of variance (11.2%) in floristic composition and caused an increased frequency of non-palatable species and resistant species to grazing and soil compaction as well as increasing of annuals including Bromus tectorum, Picnomon acarna, Minuartia picta, Rochelia disperma, Holesteum umbellatum, Lophocloa phlorides, and Valerianella vesicaria. These species were identified as invasive species based on density, abundance, and available resources. On the other hand, it seems that the spread of palatable species such as Vicia sativa,Trifolium physodes, Lens cyanea, and Lathyrus inconspicaus in the moderate grazing site indicates the role of balanced livestock grazing in maintaining the proper species composition in rangelands.
Hamid reza Mehrabi; Mohammad reza Chaichi; Reza Tavakolafshari; Hasan Madah Arefi; Ghavamodin Zahedi Amiri
Volume 17, Issue 3 , October 2010, , Pages 489-498
Abstract
Applying methods like seed coating which result in germination improvement, reduction of environmental stresses and increase of range species establishment is utmost important. This experiment was performed to evaluate the effect of different seed coating methods on Sanguisorba minor seed germination ...
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Applying methods like seed coating which result in germination improvement, reduction of environmental stresses and increase of range species establishment is utmost important. This experiment was performed to evaluate the effect of different seed coating methods on Sanguisorba minor seed germination under drought stress and different sowing depths. A factorial experiment in a completely randomized design with three replications was conducted in this research. Treatments included three soil moisture levels (9, 14 and 21 percent of soil dry weight), two sowing depths (surface and three times the diameter of seed), and four seed coatings (control or no seed coating, organic matter, hydro gel and clay seed coatings). Germination percentage was recorded during the experiment. The results of main treatments showed that regardless of the coating type, the effect of all three coating materials on seed germination percentage was significant (p<0.01). The triple interaction effects of soil moisture, sowing depths and coating materials indicated that in surface sowing and all soil moisture levels, there was a significant difference (p<0.01) in seed germination percentage between seed coating and control treatments. No germination was observed in control treatment with 9% soil moisture and surface sowing. Germination percentage for control treatment with 14% soil moisture was 20% recorded as the second rank among the lowest germination levels. In treatment of three times the diameter of seed as sowing depth with 21% soil moisture, there was no significant difference in germination percentage between control and seed coating treatments.
Noor ... Abdi; Hasan Madah arefi; Ghava din Zahedi amiri
Volume 15, Issue 2 , January 2008, , Pages 269-282
Abstract
Atmospheric carbon dioxide concentrations have substantially increased in recent decades. Land management practices, however, offer opportunities to mitigate the rise in atmospheric CO2 concentration through sequestration of this additional carbon via storage in plant biomass and soil organic matter ...
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Atmospheric carbon dioxide concentrations have substantially increased in recent decades. Land management practices, however, offer opportunities to mitigate the rise in atmospheric CO2 concentration through sequestration of this additional carbon via storage in plant biomass and soil organic matter in a process termed terrestrial C sequestration. Rangelands ecosystems have a large potential to sequester C because they occupy about half of the world's land area. In Iran, the Astragalus rangelands with about 17 million hectare area have 10% of the country land area and have the important role in carbon sequestration. In order to investigation the role and potential of Astragalus rangelands in carbon sequestration, a study was carried out at a key area of Astragalus verus-Bromus tomentellus vegetation type in Malmir rangeland site, Shazand township of Markazi province and the content of aboveground and underground biomass carbon, litter carbon and soil organic carbon was determined. The results showed that the total carbon sequestration per hectare was 32.95 ton and 87.43 % of total carbon sequestration was soil organic carbon. The results of biomass carbon distribution showed that the carbon content in aerial biomass was higher than underground biomass. Correlation and stepwise regression analysis revealed that the content of carbon sequestration was positively related to Astragalus height and volume, aerial and underground biomass, total biomass, litter amount and soil organic carbon (SOC) content. It was concluded that the Astragalus rangelands have a large potential to sequester carbon and the soil is most important sink for organic carbon storage in this rangelands