Desert
Volume:25 Issue: 1, Winter - Spring 2020

Homand Absard Rangeland Research Station is located 70 km northeast of tehran and 15 km southeast of Damavand with an altitude of 1972 m a.s.l., an average annual rainfall of 333 mm,  and a cold semi-steppe climate. In order to compare  the seed production of Vicia villosa under different cultivation seasons and methods, the seeds were initially collected from natural habitats similar to the mentioned station. Afterwards, seed characteristics  such as viability, and seed vigorwere examined. Two sowing methods, namely row seeding and seeding with rainfall storage, through crescent contour trenches and spring and autumn sowing dates, were considered in a complete randomized block design with three replications. Statistical analysis was performed by independent t-test using SPSS 21 software.  According to the obtained results, no establishment was recorded for spring sowing; furthermore, in autumn sowing,  the two cultivation methods were not significantly different in terms of establishment (p <0.05). However, the results of mean comparisons showed that in autumn sowing, the crescent seeding with an average seed production of 68.36% was superior to the row seeding with an average seed production of 59.12%.

Forage production of rangelands differs during different times of grazing season and in the same month of different years. In range management projects, grazing capacity calculated once during the grazing season, which coincides with the maximum production of rangeland species. This may cause more livestock entry into the rangeland during the grazing season, leading to more degradation. Therefore, it is necessary to measure forage production during the months of grazing season over a few years, based on which the long-term grazing capacity of key range species could be estimated. Production variations of the key species, namely Artemisia sieberi, Salsola laricina, and Stipa hohenackeriana were investigated in Khoshkerood-e-Saveh site in growth and grazing season over the course of three years. For this purpose, the production of each species measured in a one-hectare exclosure with one month intervals until the growth dormancy. After air-drying, forage production was analyzed by SAS software. Based on the results, due to the high variability of monthly and annual precipitation in the region, forage production of key range species had significant differences at P ≤5% level. The maximum and minimum mean production (543 and 388 kg/ha) belonged to 2009 and 2008, respectively. According to the production fluctuation in different years, it is recommended that range management plans account for the long-term average of good production.

Dust storm is one of the criteria for air pollution, and pollution by Heavy Metal(HM) is one of the major environmental problems in the world. The objective of the present study was to assess some of HMs concentrations in the leaves and bark of cypress and atmospheric falling dust along the Yazd highway, Yazd Province, Iran. The total concentrations of cadmium (Cd), cobalt (Co), copper (Cu), nickle (Ni), lead (Pb), zinc (Zn), iron (Fe) and manganese (Mn) in the dust and plant samples were measured using atomic absorption spectrophotometry after digestion with acid. The results showed that the concentration of Zn and Cd metals in falling dust were the highest to the lowest, respectively. The distance from the highway significantly influenced the concentration of HMs in leaves and bark of the cypress tree. Moreover, the effect of HMs on the bark of this tree was higher than that of leaves, except for Cd, Co, Cu and Mn. Concentrations of Zn, Co, Ni and Fe increased with the increase in the distance from the highway due to multi-directional winds and the presence of other contaminants. The Pearson correlation analysis between the HMs found in the falling dust and Thuja orientalis L. showed that the input and controlling factors of these metals in the cypress tree were probably the same as the dust. The results further showed that the Thuja orientalis L. leaves with a metal accumulation index of 1973.16 mg/kg were more able to simultaneously absorb different metals. Therefore, since this green belt surrounds the Yazd urban area, it is expected that a significant amount of HMs will be absorbed by these trees.

Phosphorus (P) is a key element in many biological processes of plants and animals. We aimed to investigate the effect of different salinity levels and Ca:Mg ratios of irrigation water arid lands on soil available P, soluble P, and P absorbed by the pistachio plant. For this purpose, a greenhouse experiment was conducted by sowing the seeds of pistachio in a factorial randomized block design with four soil salinity levels (S1 (6 dS.m-1irrigation water salinity, leaching fraction (LF) = 50), S2, S3, and S4 (9 dS.m-1 irrigation water salinity, LF = 50, 30 and 20, respectively)) and three Ca:Mg ratios (M1, M2, and M3 equal to 1, 0.5, and 0.25, respectively). After harvesting the plants, the amount of soil available P (Po), water-soluble P (Pw), and total P (Pt) at soil depths of 0-5, 5-25, 25-50, and 50-75 cm, and P concentration in the leaves of Pistachio seedlings were measured.The results showed that the salinity of soil saturated extract had no significant effect on Po, Pw, and Pt. The reduction in Ca:Mg ratio increased Po and Pw in soil surface but it did not affect Pt. Increasing salinity from S1 to S2 augmented plant P uptake but at higher salinity levels, P uptake was reduced. The decrease in Ca:Mg ratio had no significant effect on plant P contents.

Using plants for the remediation of soils contaminated with heavy metals is an economical, cheap, and effective strategy. The goal of this research was to study the effect of sewage sludge and drought stress on the remediation of cadmium in soil, root uptake by corn plant. This study was carried out on corn in factorial design experiment based on completely randomized design with three replications in three soil pollution levels, namely B1(control soil), B2 (Cd with soil, 20 mg.kg-1), B3 (Cd with sewage sludge with soil treated, 20 mg.kg-1), and two different irrigation regimes, including A1 (full irrigation) and A2 (limited irrigation). The research included two irrigation treatments at two levels of irrigation: 100% of field capacity (A1) and deficit irrigation at 80% of field capacity (A2). The results showed that the soil treated with cadmium and sewage sludge decreased dry and fresh wet weight plant. Sewage sludge increased the amount of cadmium concentration in shoot almost 21% toward the soil treated with cadmium (soil without cadmium); however, it could not increase cadmium uptake due to the decrease in shoot and root dry matter. In limited irrigation, cadmium concentration in shoot and root was reduced by 46 and 16% toward control treatment, respectively. With increasing irrigation and in the soil treated with sewage sludge, the transfer factor of cadmium from root to shoot dry matter increased. The translocation factors were 0.65, 0.5, and 0.13 for sewage sludge contaminated treatments, cadmium-contaminated treatments, and control treatments, respectively. Based on the results, growing plants at an irrigation level of 100% offered nest advantages in terms of higher biomass and efficient Cd removal.

In this paper, we investigated two originated metamorphosed harzburgites of the metaperidotite complex from the northern part of the Gishaki area. Harzburgite rocks, as main ultramafic complexes of the studied area, were exposed in the scattered location of the area. Despite intensive alterations, harzburgitic units were discriminated using petrography and Raman spectroscopy studies of relict minerals. There are two meta-harzburgite types of regionally metamorphosed harzburgites (R-Hz) and thermal metamorphosed harzburgites (T-Hz) with different characteristics and antigorite types. Antigorite polymorphs, structurally discriminated using Raman spectroscopy, had certain specific chemical characteristics compared with other serpentine polymorphs in SiO2, MgO, and H2O contents presented as separated fields in scatter diagrams. Reviewed antigorites illustrated general differentiations in themselves, so that polymorphs hosted by T-Hz rocks could be considered as a group with typical thermal antigorite geochemical criteria such as lower H2O (< 12% due to dehydration process), high NiO (> 0.4 wt. % due to Ni tendency to high temperature phases through the recrystallization process), high SiO2 (because of the  high silica activity in the aureole), lower total octahedral cations (due to pressure reverse dependence), and higher FeO (due to high temperature and Fe2+ activity). The increase in Si and Fe2+ activities cause to lack of Tetrahedral and presence Octahedral Tschermak substitutions as temperature dependent phenomena in thermal antigorites. Diagrams of SiO2 versus calculated H2O, SiO2 versus total octahedral cation units, and FeO versus NiO clearly distinguished thermal antigorites from former usual antigorite polymorphs. Thermal antigorite in the Gishaki serpentinites could be considered as metamorphosed products related to metamorphic aureoles.

Communication and transportation networks are among the most important infrastructures critically involved in the development of different countries. The structural and tectonic position of Iran causes significant damage to its communication networks every year. Therefore, it is essential to adopt an integrated and flexible approach for assessing seismic risk in terms of available indicators. The differential synthetic aperture radar interferometry (DInSAR) technique is among the most effective and suitable techniques for monitoring land surface change. Therefore, this research aimed to estimate the displacement rate caused by the activity of fault lines over the railway tunnels in Hormozgan. The results revealed that the displacement rate was higher in parts with a higher fault density and intersection. Specifically, the amount of displacement due to tectonic activity in the studied area was estimated between 1.2 and 2.7 cm per year. Accordingly, the railway tunnels of Hormozgan are at risk of destruction over time.

Compared to surface water, groundwater resources are the primary source of water supply in arid and semi-arid regions of Iran, hence the importance of the management of these resources .  In this regard, we assessed the effects of landuse changes on the qualitative and quantitative status of groundwater resources in Eshtehard region, Iran. Through processing and analyzing the satellite images, the region was divided into six different land uses, namely agricultural lands, Haloxylon planted area, bareland, saline lands, rangelands, and urban areas; the maps pertaining to these land uses were then prepared. The ground water table fluctuation was assessed via the quantitative data of wells in the study area during 2000-2014. IDW interpolation method was employed to study the spatial variations of parameters, such as EC, Na, SAR, and TDS; afterwards, the maps related to the qualitative and quantitative changes in groundwater were prepared. The results showed that the rangelands, bare lands, and urban areas increased, and the agricultural lands decreased during the studied period. There was more reduction in groundwater table whereas water quality dropped. Generally, water quality was reduced from west to east, and there was more decrease in groundwater table from south to north. It could be deduced that human and natural factors, particularly over exploitation of groundwater, were the main reasons for these changes.

Soil salinity undergoes significant spatial and temporal variations; therefore, salinity mapping is difficult, expensive, and time consuming. However, researchers have mainly focused on arid soils (bare) and less attention has been paid to halophyte plants and their role as salinity indicators. Accordingly, this paper aimed to investigate the relationship between soil properties, such as electrical conductivity of the saturation extract (ECe) and the spectral reflectance of vegetation species and bare soil, to offer a method for providing salinity map using remote sensing. Various vegetation species and bare soil reflectance were measured. Spectral Response Index (SRI) for bare soil and soil with vegetation was measured via the Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI), and salinity indexes. The electrical conductivity of the saturated extract, texture, and organic matter of soil samples were determined. The correlation coefficient of soil salinity with SRI, SAVI, and salinity indexes were obtained, and a model was presented for soil salinity prediction. EC map was estimated using the proposed model. The correlation between SRI and EC was higher than other models (0.97). The results showed that the salinity map obtained from the model had the highest compliance (0.96) with field findings. In general, in this area and similar areas, the SRI index is an acceptable indicator of salinity and soil salinity mapping.

Indirect measurement of soil electrical conductivity (EC) has become a major data source in spatial/temporal monitoring of soil salinity. However, in many cases, the weak correlation between direct and indirect measurement of EC has reduced the accuracy and performance of the predicted maps. The objective of this research was to estimate soil EC based on a general linear model via using several soil properties. Through calibration equations, the error involved in such model-based data was calculated and employed in mapping soil EC using kriging with measurement errors (KME) method. The results were then compared with those of ordinary kriging (OK) and co-kriging (CK). Soil samples were taken from the depth of 0-20 cm in 78 points with spatial intervals of 500 m from an area of 40 km2, and they were analyzed for their electrical conductivity (EC) and certain other soil properties. Measured soil EC data (hard data) and auxiliary soil data were further used to develop the semi-variance and cross-semi-variance functions; moreover, soil salinity prediction was done on a grid of 100 m with OK and CK methods. Afterwards, the most optimal EC estimation model was developed using auxiliary soil data and GLM. As predicted values always involve uncertainty, the error involved with the predicted values was calculated and then the calibration equations were adjusted. Lastly, soil salinity was predicted using KME method. Results showed that the OK method had the lowest MSE and RMSE values, 0.65 and 0.8 dS m-1, respectively. Furthermore, among the auxiliary data, pH and silt content resulted in some of the best cross-semi-variance functions, among which, silt had a better performance regarding the spatial prediction of soil EC. The GLM model developed with the calculated error and KME resulted in predictions close to those of OK method (with MSE and RMSE of 0.74 and 0.86 dS m-1, respectively). KME method provided the possibility of merging error resulting from the use of soft data, derived from prediction equations; therefore, it successfully improved the spatial prediction of soil electrical conductivity

Environmental contaminations resulting from mining operations play an important role in the collapse of ecosystems balance. In order to measure vegetation characteristics and to study soil and plant contamination in rangelands surrounding bauxite mine, a systematic random sampling was done according to physiognomy and homogeneity of vegetation cover. Sampling was performed using a 50-meter transect in three areas including near the mine (0-200 m), medium distance from the mine (200 to 500 m) and long distance from the mine (500 to 1000 m). Soil sampling sites were systematically selected from the middle of transects. In each region, three samples of the aerial parts and leaveswere randomly taken from Zygophyllum eurypterum plant with three replications. Then the concentration of heavy metals in soil and plant samples was evaluated using X-ray Fluorescence Spectroscopy, S4-Explorer model. The results showed that the highest and lowest metals concentrations in all soil and plant samples were obtained at a distance of 200 and 1500 meters from the mine, respectively. The overall evaluation results based on the integrated pollution index and mean of pollution degree showed that the pollution potential of the study area is low to moderate. The findings also indicated that the soil surrounding the mine is contaminated with aluminum, titanium, antimony and iodine.

Application of green walls still has not attracted interest among the contractors and people, and this can be due to poor growing performance of the plants on these systems. This study investigated the effect of four growing media types (30% cocopeat + 65% perlite + 5% vermicompost, 30% soil + 65% perlite + 5% vermicompost, 30% mushroom compost + 65% perlite + 5% vermicompost and regular soil as the control) on the performance of three plant species (Frankenia thymfolia, Vinca minor, and Potentilla sp.) on green walls under arid climate of Mashhad city in Iran. In the control growing medium with no organic matter, Frankenia maintained the highest moisture and the lowest temperature compared to the other growing media types. The growing media did not affect the root and shoot fresh and dry weight and leaf relative water content of the Frankenia. Vinca minor in the cocopeat and mushroom compost produced the highest root fresh and dry weight; however, changing to the growing media types enriched with organic matter content did not affect the shoots fresh and dry weight of this plant type. The growing media containing organic matters compared to the control growing medium, improved relative water content of the Potentilla leaves. The growing media containing organic matters, especially mushroom compost, had positive effects on improving the growth performance of the green walls, through maintaining the moisture content of the media, and thus the relative water content of the leaves, which enhanced vitality of the plants.

Rangelands are very diverse, and they spread from low vegetation desert areas to those with more rainfall and more cover In saline and desert areas, there are many restrictions on vegetation establishment, hence the use of amendments. The study area is located south of Nazarabad city in Alborz province, Iran. In this study, different amendments, such as mineral biochar, arbuscular mycorrhiza fungi (AMF), and acrylic resin polymer (ARP) were utilized at the base of Nitraria schoberi seedlings. Each amendment was used at four levels. A total of 13 treatments (each treatment with 10 replicates) were evaluated. Five soil samples were taken from each treatment to determine the physical and chemical properties of soil (pH, EC, C, N, P, K, C/N, bulk density, particle density, pores, moisture, soil texture) for testing. The results showed that on average, more than 60% of the soil texture was clay. Furthermore, the used amendments had different effects on the physical and chemical properties of the soil. Biochar increased the carbon and nitrogen content of the soil at all levels. Moreover, AMF increased soil nitrogen and carbon, and ARP reduced soil bulk density and increased soil porosity, moisture, nitrogen, and carbon content. With increasing the level of biochar and ARP, negative effects were observed, and these amendments increased soil acidity and salinity in the study area; however, AMF reduced the soil salinity in the study area.