Desert
Volume:22 Issue: 2, Summer - Autumn 2017

Bicarbonate anion, has a very high concentration in the calcareous soil, and in fact, is the main cause of chlorosis in calcareous soils. This study was conducted to evaluate eight soybean cultivars with iron deficiency and bicarbonate presence. The present research was carried out with the aim of assessing the effect of irrigation with water containing bicarbonate on enzyme activities and Fe and Zn uptakes in soybean. We also compared Fe-efficient and non-Fe-efficient varieties regarding their tolerance against bicarbonate stress. This experiment was done in two parts; the first part was performed in order to identify Fe-efficient and non-Fe-efficient varieties (8 soybean varieties: ‘Perishing’, ‘Zaan’, ‘Clark’, ‘Williams’, ‘M7’, ‘M9’, ‘B.P’, and ‘L17’). ‘Perishing’, with an Fe efficiency index of 0.98, was considered Fe-efficient, and ‘Clark’, with an Fe efficiency index of 0.43, was identified as non-Fe-efficient. In the second part, the treatments included two levels of Fe, four levels of bicarbonate (0, 10, 20, and 40 mM), and two varieties different in terms of Fe uptake (Fe-efficient [‘Perishing’] and non-Fe-efficient [‘Clark’]) were selected. The results showed that under conditions of bicarbonate stress caused by the irrigation water, the Fe-efficient variety (‘Perishing’) had more resistance than the non-Fe-efficient variety (‘Clark’). Zinc uptake by ‘Perishing’was greater than that by ‘Clark’. The activity of catalase enzyme decreased with increasing the bicarbonate concentration, while that of super oxide dismutase increased in both varieties, but more strongly in ‘Perishing’.

It is widely known that the development of gullies causes the loss of a great amount of soil and can be considered as one of the principal causes of geo-environmental degradation. The study area of the present research is located in the eastern shores of Urmia Lake. This study sought to evaluate the rate of growth and effective factors on the area’s gully dynamic over a year. To achieve this goal, levels of Electrical Conductivity (EC), Sodium Adsorption Ratio (SAR), pH, types of soil, and morphometric analysis were used for categorizing and analyzing effective factors on the creation of gully erosion. In addition, as the climate index, the coefficient of moisture in the area’s formation for analyzing the area’s gully erosion potential was also employed as relevant indicators. The results based on climate indices show that the area’s gully erosion potential is high. Analyzing the taken samples’ structures indicated that the constructing components of geological formations provided highly appropriate conditions for vertical and horizontal leveling of gullies because of the weak building of aggregates in a way that the results of the morphometric monitoring of the gullies represent the area’s high growth speed and dynamicity. High accumulation of soluble salts especially high values of SAR and EC have led to dissolution erosion that provides the conditions for creating tunnel erosion. The results of the research showed gully erosion formation in the study area and its expansion due to two factors, climate factors together with the chemical and physical characteristics of an area’s soils. The results of the present research are of great importance for gully erosion modeling tasks in the study area and can be used as the base of future researches for identifying the relevant criteria and indicators in gully erosions.

Researchers studying on adaptation and resilience of systems mainly seek to reduce the vulnerability of extremely complex social-ecological systems against potential changes. Since major portion of natural resources of Iran is interrelated with various users and social groups. Present study focused upon the necessity of studying structural characteristics of social capital of rangeland users in Kalateh Rudbar region of Damghan county. In this way, we used the network analysis method for improving the resilience of social-ecological systems. Accordingly, applying survey method and through interview with target groups and filling in network analysis questionnaire, interpersonal trust and collaboration ties of local beneficiaries were investigated. Applying whole network method for pin pointing local beneficiaries, all rangeland users of three traditional boundaries i.e. Espiro, Goormomenin, and Changi in Kalateh Rudbar region of Damghan county in Semnan province were interrogated. It was found out that the level of social capital among rangeland users of Espiro traditional boundary was high which implies that the resilience of social system against natural system changes is higher. In Changi and Goormomenin traditional boundaries, social capital and cohesion were estimated weak. Therefore, the policy of encouraging people to join to collective activities in order to cope with natural hazards including draught and inappropriate utilization must be put into practice. It can be inferred that the resilience of rangeland users against natural hazards in Espiro traditional boundary was higher than that of the two other boundaries; therefore, implementation of collaborative management in this traditional boundary was facilitated.

Weather and climate have a strong influence on tourism and the recreation sector, which is a very important industry. Since tourism is becoming one of the main industries all over the world, it plays an important role in promoting national and local economic development. This paper attempts to show the role of climate in tourism seasonality and tries to study the impacts of climate resources on tourism seasonality using the Tourism Climate Index (TCI) in Iran. This index systematically evaluates climatic conditions for tourism activities using climate parameters. To assess Tourism Climate Index in Iran, 54 weather stations were selected. The results have been generalized in 12 monthly world maps using ArcGIS10.1. According to the results, April and October are the best time for tourism during the year, actually more area of Iran has the good potential during these months. In January and February, potential of TCI decreased and the lowest area are located in suitable class. While, based on Scott and Mc Boyle classification summer peak, dry season peak, Bi-modal shoulder peak and winter peak can be seen in Iran, most of Iran is classified in Bi-modal shoulder peak. South, south east and west of Iran have the best condition in winter peak. The peak in dry seasons including dry and without rainy seasons have the best situations in west north and east parts of Iran. Bi-modal shoulder peak, in spring and autumn, are seen in north, all east and center of Iran toward west and west east.

Soil cation exchange capacity (CEC) is a parameter that represents soil fertility. Being difficult to measure, pedotransfer functions (PTFs) can be routinely applied for prediction of CEC by soil physicochemical properties that can be easily measured. This study developed the support vector regression (SVR) combined with genetic algorithm (GA) together with the adaptive network-based fuzzy inference system (ANFIS) to predict soil CEC based on 104 soil samples collected from soil surface under four different land uses. The database was randomly split into training and testing datasets in proportion of 70:30. The results showed that both models were accurate in predicting the soil CEC; however, comparison of the performance criteria indicated that SVR results (R2=0.84, RMSE=3.21 and MAPE=7.62) was more accurate than ANFIS results (R2=0.81, RMSE=3.38 and MAPE=10.31). The results of sensitivity analysis showed that two parameters had the highest effect on both models were soil organic matter and clay content.

The objective of this study was to assess the efficiency of three mathematical models (power, exponential and logarithmic functions) for the calculation of the horizontal mass transport (HMT), as compared to the linear spline interpolation for the Cyclone Dust Sampler (CDS) and one with a Cone (CDSC), modified Wilson and Cooke trap (MWAC) and big spring number eight (BSNE). For the purposes of this study, wind erosion was measured at wind velocities of 2–7 ms−1 on a clay loam soil in wind tunnel experiments. The test results showed that the HMT of BSNE, MWAC, CDS, and CDSC samplers, calculated by these equations, fitted well to each other (p

The narrow genetic variation of bread wheat is one of the limitations to improve it for drought-tolerance. The research carried out to study the responses of different genotypes and traits to imposed moisture stress. The plant material comprised of 10 Aegilops tauschii accessions as well as a tolerant (BW2) and a susceptible (BW1) bread wheat cultivar. To assess the root and shoot-traits, two separate pot experiments were conducted, under normal and moisture stress conditions during 2013–14 and 2014–15 years. The majority of the traits were significantly affected by the genotypes (G), water treatments (WT), and G×WT interaction. The results revealed a high inter genus diversity for the all traits, except tillers number per plants. A19 accession was less affected by the imposed moisture stress, while A14 and A16 were the most affected ones. In addition, BW2 cultivar was more tolerant, with a greater yield, than BW1. Water use efficiency and seed weight per main spike were the most effective traits to improve grain yield. A high amount of water use efficiency, plant harvest index, spikelet number per spike, seed number per main spike, seed number per plant, biological yield per plant, and RWC, and a low amount of phenological traits (except grain filling period), excised leaf water retention, and root to shoot dry weight ratio were suggested for improvement of grain yield. Harvest index and biomass were two main-components of grain yield in the favorite (BW2 and A19) genotypes. A19 and BW2 may have value for breeding wheat better adapted to moisture stress conditions.

The effects of geological conditionwere assessed on density of Soil Organic Carbon (SOC) and Nitrogen (N)in a sequence of hillslope landscape, derived from different lithology i.e. loess deposit, reworked loess, marl with mixed siltstone and shale, reddish brown clay deposits and older loess in the semiarid area of northern Iran. However, other factors can influence SOC and N density such as land use, topography and climate with geology, pasture land use have been selected with a homogeneous climate to study their influence on density SOC and N of different lithology. Total of 108 soil samples were selected from two layers of 0-20 cm (surface) and 20-40 cm (subsurface). Results showed higher amount of SOC and N density, Cation Exchange Capacity (CEC) and silt were in surface layer of loess deposit that is related to vegetation density and root growth in this material than other conditions. On the contrary, the amounts of mentioned parameters were the lowest in marl. However, there was no significant difference between density of SOC and N in subsurface layer, but trend changes was similar with the surface. Overall, results show that there is a correlation between geological conditions and storing SOC and N. In conclusion, protection of surface and subsurface soil is important to increase density of SOC and N. Especially, overgrazing on steep slope of marl must be reduced or prohibited because rate of carbon loss to the atmosphere was significant and it is important in a changing environment from landscape to global scale.

Roads have an important role in plants dispersal on different scales. Various plant species settle on roadsides, but some of them can enter the natural environments and threaten their biodiversity. Worldwide knowledge of roadside flora is necessary for local and global management of natural areas. Accordingly, the roadside flora of Northern Khorasan rangelands was studied along the 600 km of 12 paved roads. Base on a stratified random sampling design, 38 sites were sampled by 100 m² rectangular quadrats stablished on both roadsides. Totally, 330 plant taxa of 39 spermatophyte families were identified and their life-forms and chorology were determined through botanical resources. The results showed that therophytes and hemicryptothytes were the dominant life-forms of roadside vegetation. The native Irano-Turanian elements were the dominant chorotype of roadside habitats. Number of endemic taxa (3.6%) was notable in comparison with cosmopolitan (1.2%) and alien (0.6%) species. Agropyron desertorum (Fisch. ex Link) Schult. and Agropyron elongatum (Host) P. Beauv. were the only two introduced alien species in the studied roadsides. Some of the cosmopolitan and pluriregional species such as Triticum aestivum L. were cultivated plants, but most of them were common weeds. Native weeds like Hordeum glaucum Steud. and Alhagi persarum Boiss. & Buhse had the highest frequency on the studied roadsides. The present study, therefore, revealed that the roadside flora in natural areas could have a considerable stock of native and endemic species which would be suitable for the revegetation of roadsides and the disturbed natural areas around the roads.

The paper reviews a set of soil surveys carried out in Iran using a geopedologic approach for different surveying aims in different scales. Most of these studies have implemented a similar survey method including the following steps: delineation of landforms from air photos using geomorphic and soil-landscape relationships, field check of the delineations, sample areas inventory with soils classified at the family level (USDA Soil Taxonomy), and extrapolation of the soil patterns from sample areas to the whole survey perimeter. The objectives of the paper was first to assess the accuracy and precision of this method via comparing the pedodiversity and similarity indices. Second, to find out at what level of detail or scale the geopedologic survey provides reliable information for extrapolation from visited to unvisited landscape units. The results in all types of analyses showed that differences between distribution of soil types and variables in training and extrapolation units of any landform increases with increasing scale and descending taxonomic and geomorphic categories. Therefore, it is proposed that the geopedologic soil surveys to be used not more intensive than semi-detail scales. It is concluded that the geopedologic approach is a suitable method for preparing proper foundation for pedometrics methods in all scales to study the basic and applied aspects of pedology.