Roya Ehghaghi; Asghar Mosleh Arani; Hamid Reza Azim Zadeh; Mohammad Zargaran; Bahman Kiani
Volume 22, Issue 1 , June 2015, , Pages 168-183
Abstract
The distribution and establishment of plant species is affected by plant characteristics and environmental conditions. The species of Calligonum genus, belonging to Polygonaceae family, have a wide distribution in arid and semi-arid climates. In this study, the distribution and qualitative characteristics ...
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The distribution and establishment of plant species is affected by plant characteristics and environmental conditions. The species of Calligonum genus, belonging to Polygonaceae family, have a wide distribution in arid and semi-arid climates. In this study, the distribution and qualitative characteristics of four species of Calligonum (C. stenopterum, C. persicum, C. bungei, and C. polygonoides) were investigated. In each habitat, four soil profiles were dug and soil properties including soil texture, EC, pH, lime, gypsum, SAR, and organic matter were measured. Results showed that all species needed a light soil texture, loamy-sand, with relatively high gypsum and lime content and a slightly alkaline pH. Very low canopy cover indicated a low humidity condition as well as the sever lack of organic matter in soil. Very low rainfall, large temperature differences between summer and winter, and a long dry season (10 12months) were the characteristics of the study habitats. The number of frost days in the habitats of C. stenopterum and C. persicum was lower as compared to the habitats of C. bungei and C. polygonoides, providing the conditions for growth of C. stenopterum and C. persicum, which are exclusively native to this region of Iran
Hamidreza Azimzadeh; Farzaneh Fotouhi
Volume 20, Issue 4 , March 2014, , Pages 695-705
Ali Mohammad Ghaeminia; Hamid reza Azimzadeh; Mohammad Hossein Mobin
Volume 18, Issue 1 , May 2011, , Pages 42-57
Abstract
Soil temperature is one of the most important and effective factors influencing the establishment of vegetation in arid regions. Soil temperature is affected by several meteorological parameters. The study of air temperature, rainfall and sunshine hours can be useful ...
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Soil temperature is one of the most important and effective factors influencing the establishment of vegetation in arid regions. Soil temperature is affected by several meteorological parameters. The study of air temperature, rainfall and sunshine hours can be useful to understand the variation of soil temperature. Soil temperature changes and rate of heat transport in soil profile are helpful for evaluating the amount of evaporation, plants water requirements, decomposition rate of materials, biological activities and the time of seed planting. The aim of this study is to evaluate the role of atmospheric factors in determination of the soil temperature. For this purpose, after collecting daily temperatures data of different soil depths (5, 10, 20, 30, 50 and 100 cm) in Yazd synoptic station for 2006, firstly, the effective meteorological parameters were analyzed and then soil temperature at this station was simulated by using sinusoidal changes pattern during the year. Finally, soil temperature variation curve at any depth was plotted and evaluated using the models obtained. Primary results showed that there was a significant relationship between precipitation, air temperature and sunshine hours. Measured and predicted values were evaluated in a coordinate system. The results showed that with increasing depth, the sinusoidal model predicted values underestimate. The results of calculating coefficients of Nash-Sutcliffe model efficiency (RNS2) showed that the estimated values by model for the different depths (5, 10, 20, 30, 50 and 100 cm), compared to the measured ones had efficiency coefficients as 0.92, 0.91, 0.93, 0.92, 0.94 and 0.96, respectively. Since (RNS2) value varies between- ∞ to 1, and when its value is equal to 1, the model has maximum efficiency, so, sinusoidal equations have good capability for predicting temperature variations in soil different depths.
Hamid reza Azimzadeh; Mohammad reza Ekhtesasi; Hossein qoli Refahi; Hassan Rohipour; Manuchehr Gorji; Mohammad hasan Emtehani
Volume 16, Issue 1 , December 2009, , Pages 114-123
Abstract
Reducing the length of field along the wind path can be a major factor in providing protection against wind erosion. Therefore, the study of sediment transported by wind versus the field length and maximum transport capacity is necessary. As the wind passes over eroding soil surface, the quantity of ...
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Reducing the length of field along the wind path can be a major factor in providing protection against wind erosion. Therefore, the study of sediment transported by wind versus the field length and maximum transport capacity is necessary. As the wind passes over eroding soil surface, the quantity of sediment transported by wind increases until the wind stream becomes saturated. In the other word the mass transported is limited by the emission rate of materials from the soil surface to the air flow, known as transport limiting. The field length required for the wind to reach its maximum capacity depends on the wind velocity and the components of the soil surface. The field data were collected from 1.9ha fallow lands of Yazd-Ardakan plain. Big Spring No Eight (BSNE) samplers were set up to collect samples of horizontal sediment discharge passing through a point. Twelve events data were collected and analyzed started from May 2006 to may 2007. Two methods were adopted to determine the maximum transport capacity; 1) Fitting the mathematic equation of and 2) Direct measurement of transport capacity. Variance analysis and t-test paired data results showd that, there was no significant difference between the results of these two methods.