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.
Ali Jahani; Vahid Etemad; Mohammad Doolati; Nazi Avani
Volume 18, Issue 3 , September 2011, , Pages 463-473
Abstract
Production of native and non native species in the nursurey is considered as one of the raw materials for reforestation in arid regions. Two important factors affecting the seedling production in the nursery are seed density and seed planting depth which extensive studies have been done in this area. ...
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Production of native and non native species in the nursurey is considered as one of the raw materials for reforestation in arid regions. Two important factors affecting the seedling production in the nursery are seed density and seed planting depth which extensive studies have been done in this area. Therefore in this research the effect of seed density and planting depth on height, diameter growth and viability of H. persicum have been investigated. Haloxylon plantations of Hossein Abad in Qom province with an area of 3180 hectares, is located 30 km south-east of Qom city. Planting depth in four levels of 1, 2, 3 and 4 cm and seed density in five levels of 100, 200, 300, 400 and 500 seeds per 1000 m2were measured. All data were analyzed and the results showed that planting depth of 1 cm had the best results with regard to the basal diameter, height growth and viability percentage so is recommended for reforestration. Planting density of 200 seeds per 1000 m2was also identified suitable for afforestation.