فهرست مطالب

Desert - Volume:23 Issue:2, 2018
  • Volume:23 Issue:2, 2018
  • تاریخ انتشار: 1397/08/11
  • تعداد عناوین: 14
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  • D. Dunkerley * Pages 165-187

    Periodic vegetation patterns (PVPs) are striking features of many global drylands. Although they have attracted wide research study, resulting in many hypotheses, their origin and controlling factors remain unresolved. Theoretical works dominate a large literature seeking to account for the occurrence and properties of PVPs, especially banded vegetation patterns (‘tiger bush’). In light of the plethora of theoretical studies, there is a need for more empirical observation and monitoring of PVPs, especially their responses to climatic variability and to foreshadowed climatic change. This paper highlights key results derived from more than 20 years of field study and monitoring of banded vegetation in arid New South Wales, Australia, where severe drought is a recurring feature. It advances the view that in this study area, and hence perhaps in other regions, local factors including plant physiology, soil properties, and climatic characteristics result in PVPs whose development and functioning might be quite unlike those of other regions. Importantly, these local characteristics appear to confer on the regional PVPs a considerable resilience to drought, and hence perhps to climate change. The field evidence from the study area suggests that, despite predictions of a number of theoretical analyses, the PVPs are not facing imminent collapse. Generalised and non-specific models of PVPs require more realistic parameterisation and more thorough validation than has been customary, and this will require additional field evidence of the kind reviewed here.

    Keywords: Patterned vegetation, Banded vegetation, Tiger bush, Fowlers Gap, Australia
  • H. Tavakoli Neko*, A. Shirvany, M.H. Assareh, M.R. Naghavi, M. Pessarakli, A. Pourmeidani Pages 189-198

    Euphrates poplar (Populus euphratica Oliv.) is a woody species that is naturally distributed in the desert areas of some parts of Asia and Africa. Because of its outstanding features, it is a model plant to study environmental stress tolerance. This research was conducted from 2014 to 2016 in order to study the relationship between performance indices and ion concentrations. The cuttings of 12 ecotypes were collected from different climatic conditions in Iran. Salinity stress was applied using four levels of NaCl (75, 150, 225 and 300 mM) and one control sample (salt-free). The performance indices [diameter and height growth, biomass production; leaf, stem, root and total biomass] showed significant differences in salt levels and ecotypes. The ion concentrations showed significant differences in salt levels (except Ca2+) and varied in different ecotypes. There was no significant difference in salt×ecotype interaction for most of the variables. The ecotypes, treatments, (salt levels) means of performance indices and ion concentrations were separated into different groups. Correlation coefficients showed that the concentration of macronutrients had positive correlations with performance indices, and that salt ions had negative correlations. Correlation coefficients also showed that the ion concentrations had synergistic or antagonistic effects on each other. The results of this study showed that the key mechanisms of salt tolerance in this specie include: exclusion of salt from the root, compartmentalization of Na+ in plant tissue, preventing excessive reduction of K+ absorption resulting in the maintenance of the K+/Na+ balance.

    Keywords: Ions, Populus euphratica, Salt stress, Yield
  • A. Shahriar *, Gh.A. Mozaffari, S. Poudineh Pages 199-209

    The physical development of cities is always faced with natural barriers. The physical development of the city of Zabol, located in the Sistan plain, is threatened specifically with the development of sand dunes. For this reason, the region’s drought conditions were investigated and the standardized precipitation index was calculated. The results showed that with the drying of Hamoon Lake, the frequency of dust storms has increased. Zabol weather station’s anemometer data was collected, then annual and seasonal sand speed as well as the region’s prevailing weather pattern, which was drawn using Integrated Data Viewer (IDV), Wind Rose Plots (WRPLOT) and Sand Speed Graph software. The results showed that the dominant wind direction is from the North West, followed by the North winds. In addition, it was found that frequent strong winds are more important during the spring and summer. The results of drawing sand speed showed that the final direction for carrying sand is to the Southeast and the that wind's features have provided the conditions for the formation and development of active dunes. It should be noted that the development of Zabol is toward the North and Northwest. In addition, the prevailing wind direction of the region and the active sand dunes are to the North and the Northwest of Zabol. Thus, it is evident that one of the major barriers of the physical development of Zabol is the movement of sand dunes, as the development of Zabol is in the same direction of regional winds.

    Keywords: Physical development of the city, sand dunes, Sand-carrying winds, Standardized precipitation index, Zabol city
  • A. Ahmadi *, A. Kazemi, H. Toranjzar Pages 211-220

    Soil salinity phenomena are one of the main problems of arid and semi-arid lands. Saline soils constitute a huge part of Iran, and also threaten its neighboring lands. Therefore, in order to optimum exploitation of such soils, qualitative monitoring is necessary. Recently, remote sensing techniques have been increasingly applied in monitoring soil characteristics. The present study was carried out between 2014 and 2015, with the purpose of using remote sensing for mapping soil salinity in the saline rangelands of Chezan plain (Markazi province). In the first step, 50 soil samples were taken from the topsoil (30 cm depth) and their Electrical Conductivity (EC) was measured by EC- meter. To use the soil salinity map using remote sensing, we first used Indian Remote sensing Satellites (IRS) satellite imagery and the satellite’s LISS sensor (LISS III, 2008). After geometric and radiometric correction, this image was been classified using the Maximum Likelihood method. Then in the next step, Comparison of Spectrum indices were done by extracting maps of soil salinity. For this purpose, Four indices including: Brightness Index (BI), Salinity Index (SI1), SI2, and Normalized Difference Salinity Index (NDSI) were used. Among these indices, SI2 had the most correlation with ground control points (0.63 in 1% level) and is introduced as a more suitable index than others for zoning soil salinity. Regarding to the salinity map, the results showed that a sizeable portion of the study area was classified class 2 with a salinity of between 4-8 dS/m (55% of whole land).

    Keywords: Soil salinity, LISS III, Spectrum Index, remote sensing, Chezan
  • M. Mirehei *, M. Hajilou Pages 221-232

    Environmental factors are being increasingly taken into account in the increasing development of urbanization and citizen residential requirements. Climate and climate conditions are among the environmental factors that have always influenced human welfare. Climate has always been incorporated in old urban structures in Iran and can be easily observed. Despite the importance of climate-related elements in Iran, there has been a lack of sufficient consideration of climate conditions in urban planning during the period of fast-paced urbanization. However, in these last years the introduction of theories such as sustainable development, geographical elements and more specifically climate, have been incorporated in urban architecture and development. Accordingly, the present study first attempts to review some climate applications in the planning and construction of cities, and then proceeds to tackle some architectural factors and urban planning requirements (such as the indoor and outdoor spaces of a building) regarding the climate in the geographical area of Qom, Iran. For this purpose, Mahoney tables have been used for climatic design, and then the data was analyzed by implementing the descriptive-analytical method. Results of the study showed that various urban and architectural planning methods including compression, reducing the size of openings, double glazing windows and others have reduced the harshness of Qom’s climate and changed a threat into an opportunity.

    Keywords: Environmental factors, Climate, Architecture, urban development, Desert areas, Iran, Qom
  • M. Samiee, R. Ghazavi *, M. Pakparvar, A.A. Vali Pages 233-242

    Saline lakes can increase the soil and water salinity of the coastal areas. The main aim of this study is to distinguish the characteristics of the spectral reflectance of saline soil, analyze the statistical relationship between soil EC and characteristics of the spectral reflectance of saline soil, and to map soil salinity east of the Maharloo Lake. The correlation between field measurements of electrical conductivity and remote sensing spectral indices was evaluated using multiple regression analysis. In this study, Kriging, CoKriging, and multiple regressions were applied for soil salinity mapping and classification using 100 soil samples. After radiometric, geometric, and atmospheric corrections of Landsat OLI images, the statistical correlation between the electrical conductivity of field measurements and spectral reflectance was investigated. According to obtained results, the modified salinity index (MSI) with the highest correlation (R2=0.78) was used as an auxiliary variable for the coKriging method. Kriging with a spherical model was selected for soil salinity mapping (RMSE = 50.5 and R2 = 0.18). The RMSE and R2 values for CoKriging were (43.2 and 0.42), respectively. Because of their acceptable R2 (=0.65) and low standard deviation (33.8) for salinity analysis, MSI and difference vegetation index (DVI) were used to estimate and zonate soil salinity in the study area. The results showed that soil salinity could be estimated via spectral indices with acceptable accuracy, R2 and RMSE. Overall, this method leads to a decrease in the costs involved in the soil mapping of saline soil areas.

    Keywords: Soil salinity, Maharlo lake, Geostatistical methods, Regression, Arid environment
  • M. Fatemi *, M. Narangifard Pages 243-253

    Droughts are one of the most damaging climatic phenomena, and the most complex natural hazard which affects the economy, agriculture, public health and environment in large areas. The aim of this study is to compare drought indicators derived from tropical rainfall measuring mission (TRMM) data in the south of Iran. Also the TRMM rainfall was considered, so as to investigate changes in the rainfall pattern over the area. In this study, five meteorological drought indices, including the standard precipitation index (SPI), deciles index (DI), z-Score, Standard Index of Annual Precipitation (SIAP) and Percent of Normal Precipitation Index (PNPI) derived from TRMM data at 0.25° × 0.25° spatial resolution are compared to monitor droughts in the South of Iran. The results showed that the SPI index was strongly correlated with other drought indices. The maximum relation of the SPI index with other drought indices was investigated, and the PNPI Index was found to have the most correlation, with a correlation coefficient of R = 0.995 and a coefficient of determination of R2 = 0.99. Also a strong inverse relationship was observed between rain and longitude while altitude and latitude were found to be poorly related.

    Keywords: Rain, Drought indices, South of Iran, TRMM
  • M. Mirzavand, H. Ghasemieh *, S.J. Sadatinejad, R. Bagheri, I.D. Clark Pages 255-264

    Owing to population growth and water demand, coastal aquifers all over the world are over–pumped, resulting in serious problems such as saltwater intrusion. So, in these conditions, assessing the groundwater system’s vulnerability and finding areas with saltwater intrusion potential are vital for the better management of aquifers. In this study, AHP-GALDIT was applied to saltwater intrusion vulnerability assessment in the Kashan plain. The AHP model determines the weight of each indicator in the GALDIT model. The most important indicators of the AHP model are distance from shore/high tide, groundwater head, groundwater system hydraulic conductivity, impact of present status of saltwater intrusion, saturated media depth, and groundwater occurrence. The AHP-GALDIT distribution map indicates four different rating areas in the Kashan plain, including: more than 10, 7.5 to 5, 5 to 2.5 and less than 2.5, which denote high, average, low, and very low vulnerability, which correspond to approximately 16.16, 25.51, 21.26, and 36.05% of the entire area, respectively. The results reveal that the northeastern part of this inland coastal aquifer is currently undergoing saltwater intrusion. But, it is not clear whether the source of salinity is saltwater intrusion from the “salt lake”, upcoming processes, or other sources. This study proves that the GIS-based AHP-GALDIT model is suitable to determine vulnerable sites with high accuracy by using the set of indicators affecting the vulnerability assessment.

    Keywords: Inland coastal aquifer, Saltwater intrusion, Vulnerability map, AHP-GALDIT method
  • F. Alasvandyari, B. Mahdavi * Pages 265-271

    The influence of exogenous application of glycine betaine (GlyBet) was examined on photosynthetic pigments and ions concentration of safflower under salinity stress conditions. The experiment was performed in a randomized complete block design arranged as a factorial with three replications. Salinity treatments (0, 50, 100, and 150 mM) were applied using sodium chloride (NaCl). GlyBet (0, 10, 30, and 60 mM) sprayed onto leaves of safflower. The results showed that an increase in salinity levels led to an increase in Na+ content and Na+/K+ ratio and a reduce in shoot and root fresh weight, chlorophyll, carotenoid, photosystem II (PS II) activity , K+, and Ca2+ contents. In all stress levels, foliar application of 30 and 60 mM GlyBet led to an increase in chlorophyll a, b and total chlorophyll, carotenoids and PS II activity than control. Also, in all salinity levels, foliar application of GlyBet reduced Na+ content and Na+/K+ ratio of the plants and increased their K+ and Ca2+ contents. These results suggest that the application of 30 and 60 mM GlyBet under salt stress conditions had the largest effect on photosynthetic pigments, PS II activity, and K+ and Ca2+ contents of safflower.

    Keywords: Glycinebetaine, Chlorophyll, Safflower, Salinity Stress
  • S.S. Moosavi*, F. Ghanbari, M.R. Abdollahi, A.R. Kiani Pages 273-283

    Improved drought-tolerant maize hybrids would significantly reduce water consumption and increase yield in arid environments. Our knowledge about genetic parameters is very essential before starting a successful breeding program. The present research was carried out throughout three successive years between 2013-15 to reveal the pattern of inheritance in yield, yield-components and related phenological traits under moisture stress conditions. There was a positive and significant heterosis for grain yield/plant (GY), ear biomass/plant (EB), ear length (EL), grain number/row (GN) and plant height (pH). Inadequacy of additive-dominance model for the majority of the traits, indicate the role of epistatic in governing inheritance of those traits. There was a big-difference between dominance and additive effects for some traits, showing complete dominance and over dominance control the traits. Although dominance variation was greater than additive effect for phenological traits, however, the effect of additive effects was greater than dominance for GY, EB, ear-harvest index (EHI), row number/ear (RN) and ear-wood percent (EWP). Broad sense and narrow sense heritability ranged between 43.33-87.67 and 12.28-47.41, respectively. Meanwhile, the minimum gene number ranged between 1 to 6.53 in the studied traits. Due to the notable role of additive effects in governing the important traits of EB, EHI and RN, selection in early generations using the pedigree method for them, can be efficient to improve drought-tolerance and stabilize GY under moisture stress conditions.

    Keywords: Generation mean analysis, Genetic parameters, Water stress
  • M. Bagheri Bodaghabadi * Pages 284-293

    After collecting data, in researches, the type of data distribution must be determined; since any analysis requires the distribution of its own data. Soil properties, such as salinity, are also the same case. Due to its direct and indirect effects on plant growth, soil salinity is an important feature that has always been investigated in agriculture and natural resources, leading to a lot of researches. These researches have often focused on the mapping of salinity using different interpolation methods and their accuracy. But the effect of the data distribution on the analysis process has been less considered. Accordingly, the purpose of this study is to investigate the effect of the distribution of soil salinity data on soil salinity mapping using Kriging method. For this purpose, 610 soil samples were taken from 0-50 cm soil depth based on a grid method and their salinity (Electrical Conductivity, EC) was determined in saturated paste extracts. Variography operations for data were performed based on both, the original distribution of the data and the usual data distribution employed for Kriging i.e. normal distribution. Salinity maps were obtained for both data distributions. Estimations were made using cross-validation approach. According to the findings, only the fitness criterion (R2) is not enough to select the optimal variogram model, while other criteria such as the proportion of the spatial structure, residual sum of square (RSS) and the nugget effect should be analyzed as well. The results showed: 1- the accuracy of the estimation based on the original distribution of the data, (i.e. non-normal distribution) which was greater than the accuracy of the estimated data using normal distribution; 2- the predictions and errors from the both, normally and non-normally distributed data did not have the normal distribution and 3 - data transformation had no effect on the normalization of the distribution of the predictions and the errors. Therefore, it is suggested that in the Kriging, in addition to the conventional method, i.e., performing Kriging using normal distribution data, the original data with non-normal distribution should also be analyzed. Finally, the type of data distribution and the optimal variogram model could be selected by comparing the obtained results.

    Keywords: Data distribution, Data transformation, Geostatistics, Error distribution
  • F. Nematollahi, A. Tehranifar *, S.H. Nemati, F. Kazemi, Gh.A. Ghazanchian Pages 295-306

    Developing strategies to tackle water stress in lawns in arid climate regions is significantly important. In such conditions, using growing media amendments as well as native plants can relieve drought stress in different growing stages of the plants. This study was carried out to investigate the effects of some types of soil amendments on the emergence and early seedling establishment of tall fescue (Festuca arundinecea Schreb ‘GazBorkhar ecotype’) under water stress conditions. The experiment was performed in a factorial trial based on a completely randomized design with three replications. The first factor, water stress, was applied based on field capacity (FC) at three levels (80% FC (control), 60% FC and 40% FC). The second factor, growing media amendments, was applied at nine levels of municipal solid waste (MSW), vermicompost (5% and 10% w/w), Stockosorb® (1% and 3% w/w) or zeolite superabsorbent (4% and 8% w/w) which were mixed with loam soil, and the loam soil was used as a control treatment. Theresults showed that using an irrigation system at 60% FC during seed emergence and early seedling growth did not reduce the quality of the turf grass, and also, in many cases, led to a higher quality lawn compared to the control, leading to water saving in turf grass management. Using MSW and manure vermicompost as soil amendments could maintain soil moisture and water supplement for the improvement of morphological, physiological and visual quality of this ecotype of Festuca arundinacea Schreb.

    Keywords: irrigation, Manure, Municipal solid waste (MSW), superabsorbent, Tall fescue, Vermicompost
  • B. Izadi, S. Ghazanfari *, S. Mohammadi Pages 307-314

    Aridity as a spatial concept and drought as a temporal concept have always been studied in different aspects as two distinct categories. However, both concepts indicate anomalies from normal condition. Several indices have been introduced to examine each of these concepts using one or more hydrological cycle’s components. Meanwhile, soil moisture and changes in its spatial and temporal variations can be considered as one of the most important factors in detecting the drought and determining the areas of drought. Due to difficulties including cost and time consuming measurements, soil moisture has not been used so far. In this study, the intensity and the persistence of drought in Kerman province were evaluated using soil moisture from the output of NASA Global Land Data Assimilation System (GLDAS). For this purpose, the new GLDAS based Aridity and Drought Index (GADI) was used, which realized the drought and aridity in each region simultaneously. The soil moisture time series in four soil layers were derived from NOAH land surface model for the years 1953 until 2017. GADI were employed to map aridity and drought conditions. The results showed that the severity of drought increased in lower soil layers. The low percentage of soil moisture in the lower layers indicates that lower layers had not been fed from rainfall as a result of sever evaporation losses. This also shows the existence of long-term droughts in these layers.

    Keywords: Drought, Soil moisture, GADI index, Land surface model
  • I. Esfandiarpour*, Z. Mosleh, M.H. Farpoor Pages 315-325

    Comparing the ability of ST and WRB systems to describe soils with clay-enriched horizons was the aim of the present research. In arid and semi-arid regions of Iran, two study sites were considered. Three pedons at each study site were selected, described and sampled. Soils were classified based on ST (2014) and WRB (2015) systems. The micro-morphological investigations were done to confirm the illuvial clay accumulation in Bt horizons. Results showed that the required characteristics of an argillic horizon were not met in any of the Bt horizons. The poor correlation between ST and WRB systems was related to the different definition and criteria of clay-enriched horizons in the systems. Using “Differentic” and “Cutanic” qualifiers, the WRB system could describe properties of an argic horizon more efficiently than the ST system. Although the evidence of clay illuviation was observed as lamellae in some argillic horizons in the arid study site, the ST system could not display this characteristic. The WRB system indicates the presence of lamellae using a “Lamellic” qualifier in some cases. These issues are disadvantages for both classification systems in describing the soils with clay-enriched horizons. Defining Natrisalids great group and new subgroups including Calcic Natrisalids, Lamellic Argigypsids and Lamellic Calciargids seems necessary to improve deficiencies of both classification systems. Adding the “Lamellic” qualifier for Calcisols in the WRB system is highly suggested.

    Keywords: Clay coating, Illuviation, Lamellae, Luvisols, Soil classification