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Showing 2 results for Sheikh

Hesel Poori, Vahedberdi Sheikh, Hassan Yeganeh,
Volume 15, Issue 3 (11-2021)
Abstract

The most important indices (or indicator) for soil quality assessment are water infiltration rate into the soil and soil hydraulic conductivity. They play key roles in various issues of watershed management, soil and water conservation and hydrological modeling. By definition, infiltration is the water entry from the thin surface layer of the soil into its profile. Numerous factors such as intrinsic properties of soil, amount of vegetation cover, land use type and soil compaction affect the rate of infiltration. The stakeholders of Aq Qala winter rangelands in northeast of Iran are facing the challenge of water deficit both for drinking water and wateing the livestock during almost the whole grazing period. To solve the problem, they buy and transport water by tractors and tankers. Due to the flat topography of the plain, tractors and tankers commute from many paths without considering the environmental consequences and causes surface layer soil compaction over vast areas. This reduces rainfall infiltration and destrucs vegetation cover of the rangelands at a significant level. This study aims at investigating and quantifying these consequences on the hydraulic properties of topsoil. Infiltration rate was measured by two methods of double cylinder in the field and Lab. with constant head water and disk infiltrometer, measuring saturated hydraulic conductivity by applying constant head of water on undisturbed soil samples contained in metal rings. Using independent t-test, the hydraulic properties of the soil were compared. Samples were taken from the controls and the whecle wheel passage areas. The results showed that there was a significant difference in 95% confidence level between them. In other words, the traffic of water tankers has caused soil compaction and reduced the permeability of the topsoil in the studied rangelands. Result of the study suggests that increasing traffic routes, will create serious ecological consequences in the long term. Also, the analysis of physical and chemical properties of the soil in the area showed that except for the pH parameter, other parameters have a significant difference between the traffic routes and control sites.
Asiyeh Sheikhzadeh Ghahnaviyeh , Mastafa Tarkesh Esfahani, Hossein Bashari, Saeid Soltani Koupaei,
Volume 15, Issue 4 (12-2021)
Abstract

Climate change has far-reaching consequences on many ecosystems around the world and induced large-scale shifts in species distribution. Astragalus verus Olivier is a plant with medicinal, industrial, and soil protection value that its geographical distribution has declined considerably in recent decades. This study aimed to predict the distribution of A. verus under climate change scenarios in Isfahan and Chaharmahal va Bakhtiari provinces. The stratified-random sampling method was used to collect the presence points of the species in different altitude levels in 83 rangeland places.  The random forest model was used to model the species distribution in the study area. The Biomod2 package in R software was used to run CCSM4 general circulation model and assess the effects of climate change on the species distribution in the current condition and 2050 under two scenarios of RCP2.6 and RCP8.5. Bio1, Bio5, Bio19, and altitude were identified as the main predictive variables after performing the Pearson correlation test and removal of high correlated layers. The results showed that the random forest model had excellent performance, with AUC and TSS values of 0.9. The highly suitable habitat area of A. verus in the current condition 6917 km2, which occupies about 5.6% of the total study area. According to the results increasing temperature due to climate change will lead to a decrease in the highly suitable area of the species by about 56.5% under the optimistic scenarios and 88.3% under the pessimistic scenarios, respectively. The results indicated that the species habitat will move to higher altitudes with lower temperatures. The results of this study can be used for identifying threatened habitats and reintroduce this species to degraded habitats in the Zagros and Central Iran.

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