نشریه مهندسی اکوسیستم بیابان
پیاپی 20 (پاییز 1397)

The microbial habitats formed through plant patches, as fertile islands, are an effective factor in the development of vegetation and improve the soil surface characteristics of saline ecosystems. The pulping plant is the most economical solution for improving the saline soils, in this way, toxic ions, especially chlorine and sodium, are removed from the soil by salinity resistant plants. The purpose of this study was to evaluate the effect of various halophyte species on soil characteristics in aradiation zone and to determine the species with the highest positive and maximum effect on soil condition improvement in Urmia Soporghan region saline habitats.

To conduct research, the plant type Halocnemum strobilaceum-Atriplex verrucifera which represents a large area of saline rangelands around the Lake Urmia, has been selected by spotting along two 150-meter transects parallel to the salinity gradient and the distances between them, was considered as a patch between patches. Soil samples were taken from the inside of the stains and the space between the patches from the soil depth with three replications. In each of the patches, the morphological characteristics of the Halocnemum strobilaceum and Atriplex verrucifera species included the large crown diameter, crown diameter, base height, collar diameter and number of spikes with three replications and the ion accumulation value (Elements) in their air organs. Using independent t-test, the values ​​of measured parameters between the spots and the space between the spots as well as the average reserve of elements in the air biomass between the two species were compared.

The results showed that presence of Atriplex verrucifera has a significant effect on the increase of nitrogen content inside the droplets, but shows an increase in external staining in the case of electrical conductivity and sodium ion. For other elements, there were no significant difference between the inside and outside of the stains. There was no significant difference between the inside and outside of plantlets in the case of Halocnemum strobilaceum species, for no element. It was also observed that the amount of magnesium ion outside the stains was higher than inside them, but the amounts of calcium, sodium, and chlorine in the stains were more than opaque. The results of the analysis of the elements in the aerial biomass of species showed that there was a significant difference in the amount of sodium, potassium and magnesium elements in the two species, but there was no significant difference for other elements. Since the sodium element is the most significant element in determining the salinity index, and the storage of this ion in the strobilaceum Halocnemum is more than Atriplex verrucifera, Halocnemum strobilaceum can be introduced as a high-purity salt species.

Discussion and Conclusion: Since the sodium element is the most significant element in determining the salinity index, and the storage of this ion in the Halocnemum strobilaceum is more than Atriplex verrucifera, Halocnemum strobilaceum can be introduced as a high-purity salt species.

Drought is a natural and recurrent phenomenon. It is considered ‘a natural disaster’ whenever it occurs in an intensive manner in highly populated regions, resulting in significant damage (material and human) and loss (socioeconomic). Although drought occurs in areas with different climatic conditions. But more is happening in arid and semi-arid areas with less annual rainfall. In general, droughts occur when the amount of annual precipitation is lower than the average long-term precipitation of the area. In other words, a drought occurs when the amount of water in the water resources of a region is continuously reduced in a continuous period. Climate, hydrology and agriculture drought are different types of drought. Drought is one of the most important natural hazards that causes a lot of damage in different areas each year, and it can turn into famine. Due to variety, complexity and various effects of drought, various indicators for its analysis are used. Accordingly, most of the indicators used in drought monitoring are climate variables such as temperature, precipitation and soil moisture. Today, drought can be accurately analyzed and evaluated using remote sensing data. Accordingly, this research tries to evaluate and monitoring the drought of Sirjan basin using remote sensing data. This is an applied research, which uses NDVI (Normalized Difference Vegetation Index) products of MODIS sensor with a resolution of 250 meters and 16-hour time resolution. It also uses the LST product of this sensor with a spatial resolution of one kilometer and a resolution of 8 days. The data are for June 2000 to 2017. After receiving the data in the first step, Correction of molecular dispersion, ozone and dust absorption, radar correction and solar radiation angles were performed on the NDVI product using the BRDF (Bidirectional Reflectance Distribution Function) model. NASA has made corrections such as georeferencing, radiation calibration, the removal of cloud effects, atmospheric and steam temperatures on NASA's LST product. Then in the next step the VHI (Vegetation Health Index) index was calculated from the combination of VCI (Vegetation Condition Index) and TCI (Temperature Condition Index) indices based on the 18-year time series (2000-2017) in June. Eventually drought zoning maps based on the VHI index were produced in four classes: Severe drought, Moderate drought, Mild drought and without drought. According to the De Martonne method, a large area of Sirjan basin is located in Arid and hyper arid zone. Average rainfall is different, in northern and northeast parts is about 500 mm and decreases to 99 mm in the central and southern parts of the basin. Also, the mean long-term temperature varies from an average of 1° C to the north and north east of the basin to 18°C in its southern parts. Generally, the research findings have been shown that droughts did not have a regular trend in the Sirjan basin. Discussion and Conclusion: Basically, rainfall is the most important factor in the occurrence of drought. The results of various studies worldwide show that satellite indicators along with ground-based meteorological indices can monitor the drought trend effectively. The results of the study showed that the effects of drought on surface temperature and vegetation are different. Moreover, that depends on the various factors such as the type and characteristics of the vegetation and their temperature conditions. VHI is one of the most important combination indicators for assessing the severity of drought in different regions. Because, this indicator can simultaneously shows the effects of drought on vegetation and land surface temperature. The results showed that 2007, 2008 and 2017 have had the highest drought severity. So, in 2007, with a maximum drought, 4377 Km² of the study area suffered from severe drought. The area under severe drought in 2017 and 2008, was 3795 and 3782 Km², respectively. Accordingly; the lowest level of drought in the region was estimated in 2009, where 4195 Km² of the studied area were located in a without drought zone. In this year, only 4 Km² of the study area was located in a severe drought zone. In general, the use of drought intensity zoning maps that are produced using Combined Indicators helps in drought monitoring and planning to reduce drought losses.

Halophytes are plants that can grow in saline habitats and tolerate salinity through various ecophysiological mechanisms. Halophytes, compared to palatable and class I species, have less palatability; however, they have unique features, including that these plants are able to grow in conditions where both water and soil are saline. In other words, because of high resistance to salinity, halophytes can complete their growth stages under conditions that other plants cannot withstand. On the other hand, these plants, in the autumn and winter, when most rangeland plants have disappeared, is an important food sou rce for livestock grazing in fall and winter. Knowledge of forage quality of halophytes in saline lands and at each phenological stage is important in determining grazing capacity and grazing season as well as introducing superior species with a higher nutritional value to the beneficiaries in order to be used in haloculture programs. In the present study, the forage quality of three halophytes, growing in saline rangelands of Arak Meighan Desert, was compared at different phenological stages in order to identify the superior species to be used by the beneficiaries in the haloculture programs. Sampling was performed inside the key areas of vegetation types. For each species, three replicates and in each replicate 10 individuals were randomly selected. Shoot sampling was performed the areas where grazed by livestock. After transferring the samples to the laboratory of Qom Agricultural Research Center, they were first air dried and then dried in an oven at 70 ° C for 48 hours. Finally, each species was powdered by a mill and passed through a 1-mm sieve to do the forage quality experiments. The measurement of forage quality parameters was performed based on AOAC method in the laboratory of the Research Institute of Forests and Rangelands (RIFR) using NIR (Near Infrared Spectroscopy- INFRAMATIC8620), calibrated for halophytes. Forage quality parameters included crude protein (CP), crude fiber (CF), dry matter digestibility (DMD), acidic detergent fiber (ADF), neutral detergent fiber (NDF), water soluble carbohydrates (WSC), ash (Ash) and metabolizable energy (ME). The study was arranged in a factorial experiment based on completely randomized design with three replications to study the simple effects and the interaction effects between species and phenological stage. SAS and MSTATC software was used for statistical analysis and mean comparisons were performed by Duncan's Multiple Range Test. According to the results of analysis of variance, the effects of species and phenological growth stage on all forage quality indices were significant at 1% level, except for WSC. This difference was significant for WSC at 5% level. The interaction of species * phenological growth stage was significant only for the CF at 1% level and it was not significant for other indices.According to the results of mean comparisons, the highest content of CP, DMD, WSC, and ME (18.58, 42.5, 10.15, and 5.22, respectively) and the lowest content of ADF, CF, NDF, and ash (45.23, 29.63, 56.04, 1.83, respectively) were recorded for Ha. strobilaceum. The highest ADF (65.64), NDF (77.30), CF (56.08), and ash (7.13) content were recorded for Ni. schoberi. With the advancement of phenological stages, the content of CP, DMD, WSC, and ME were reduced, contrary to ADF, CF, NDF and ash. The CP content at vegetative growth, flowering and seeding stages was recorded to be 21.35, 15.74, and 13.30%. The DMD content during three phenological stages was recorded to be 43.12, 37.76, and 34.4%, respectively. The ADF content was recorded to be 53.1%, 57.26%, and 62.01% in vegetative growth, flowering and seeding stages, respectively. The highest and lowest CP content were recorded for Ha. strobilaceum at vegetative growth stage (25.24%) and Ni. schoberi at seeding stage (11.08%), respectively. The obtained results of the present study showed that the parameters effective on forage quality in the three species studied (Ha. strobilaceum, Ni. schoberi and Su. aegiptiaca) and in three phenological stages (vegetative growth, flowering and seeding) were significantly different. The highest and lowest crude protein content, dry matter digestibility, water-soluble carbohydrates, and metabololizable energy were observed in vegetative and seeding stages, respectively. However, the highest and lowest crude fiber, ADF, NDF, and ash were recorded in seeding and vegetative growth stages, respectively. In general, if the presence of plant species with crude protein less than 7% is high, livestock will face protein deficiency, reducing its yield and economic life in the rangeland. On the other hand, the amount of metabolizable energy to meet the maintenance requirements of a 45-kg ewe is reported to be 9.2-10.5 MJ. It is seen that the amount of crude protein in the three species studied and at all phenological stages was more than livestock maintenance requirements (CP>7%); however, metabolizable energy in all three species and at three phenological stages was less than the critical level to meet livestock maintenance requirements (ME<2/9). Halophytes were the main components of saline rangelands, containing high levels of crude protein and low levels of metabolizable energy; however, in order to be considered as an adequate diet, mixed supplement is also required. In this research, the values of desirable forage quality indices (parameters) including CP, DMD, WSC, and ME in Ha. strobilaceum was more than those of other two species, indicating the superiority of this species. In the same vein, Ni. schoberi and Su. aegyptiaca ranked second and third respectively. However, Ha. strobilaceum can be considered as a superior forage species in saline habitats to be used in haloculture programs.

Physical, chemical and ecological changes on dust deposition sites are one of the many problems caused by the occurrence of dust phenomena in arid areas. The entrance of additional salts to the ecosystem by dust, makes increased salinity and imbalanced of salts in the growth environment of plants. The purpose of this study is to determine the seasonal variations in the amount of salt sediment accumulation by dust in the arid region in north of Yazd-Ardakan plain. The study area is located in the geographical location of 53° 50' 30" to 54° 01' 35" eastern longitude and 32° 22' 45" to 32° 34' 50" northern latitudes with an average height of 990 meters above sea level and have Water and soil resources salinity problems. The average of reference evapotranspiration, temperature and annual rainfall in the studied area according to the Ardakan synoptic station in the 10-year period is 3483 mm, 18.5 °C and 75 mm, respectively. For research purpose, 128 samples of sediment deposited during the four seasons of 2017 were collected by MDCO sediment trap in an area of 20,000 ha. The soil salinity type is sodium chloride in the region. By using the OLYMPUS binoculars stereomicroscope SZ30 instrument was observed salt crystals formed at the bottom of the container from the oven. The data were analyzed using SPSS 16 software using Duncan's method (p˂0.05) to examine and compare the significant differences between the obtained seasonal data from laboratory stage. Also, to study the relationship between salinity of dust with climate parameters, three parameters include wind speed, precipitation and air temperature were obtained seasonally for the nearest synoptic stations located in the study area (Meybod and Agda). The maximum average wind speed is related to the spring with a speed of 9.3 m.s-1 and the smallest is autumn with 2.8 m.s-1. Most precipitation falls in winter, with an average of 9 mm and the summer is without precipitation. The average seasonal temperature of the region varies from 11 to 32 ˚C throughout the year and the summer is the warmest and winter is the coldest season. In order to mapping the spatial distribution of salt fallout in the area on the map, the Surfer 13 software was used by Kriging interpolation method. The result showed that the seasons of spring, winter, autumn and summer have 43.09, 29.92, 16.33 and 11.90 gr.m-2 dust fallout, respectively. Observation of the residue material in the bottom of the oven dish below the binocular stereomicroscope illustrated that were formed small crystals of salt and there was airborne salt with dust subsidence. The results of the comparison of the Average the Total Dissolved solids (TDS) of seasonal dust showed that summer with the significant difference has the highest salinity (20.28%). Autumn dust with 15.43% was in the next rank and spring and winter with 9.36% and 8.03% respectively there were no significant difference with each other. However, according to the amount of deposition of dust in the region, this amount will be equivalent to 4.03, 2.41, 2.51 and 2.40 gr.m-2 of salt at spring, summer, autumn and winter respectively.
The study between seasonal values of salinity of dust with three meteorological parameters has also shown that increasing its salinity corresponding to low rainfall and high temperature, due to lack of leaching of salts and their accumulation in soil surface, in if the wind speed shows the least correlation with the percentage of salt in the dust. Maps of dispersion of subsidence changes soluble elements with dust in different seasons showed that the areas located in the center and north of the study area have been more soluble subsidence, which is consistent with field studies. The areas in the center include the wind erosion sensitive lands with zibar and ripple mark facies and areas in the north are covered with a surface layer of salt crust. Discussion and Conclusion: Soil salinization and disruption of plant growth are the effects of saline dust on the ecosystem. One of the main sources of salt lift off by wind is accumulation of water soluble elements on the soil surface and the presence of saline soil and puffy areas. With regard to the geographical location of the northern Yazd-Ardakan plain (Figure 1), its location in the center of Iran, low rainfall (Figure 2) and the impossibility of leaching salts, salts remain at the surface and create a source of salt harvesting by the wind Which is consistent with the results of Mahmoudi and Khademi (2014) in Isfahan, which determine the cause of salt with dust is saline soils origin. The results obtained (Table 2) also showed that the range of soluble salts in the dust of the north of Yazd-Ardakan plain varied between 8.3 to 28.2% in different seasons, Which is close to 10-25% in the studied region (Lake Ebinur, China) by Erdinger et al. (2004) and Abuduwailli et al. (2008). According to the results of Saremi Naeini (2017), the probability of occurrence of erosive winds (above 6 m.s-1) in Yazd province is more than in other seasons in spring, and this probability is lower in the autumn than in other seasons, thus the higher amount of dust in these season (Table 1 and 2) can be attributed to changes in wind speed in the region and the occurrence of erosional winds, which is According to the results of Nowruzi and Khademi (2015) in justification of the time distribution of the rate of subsidence of dust in Isfahan and its relation with climate parameters. Investigation of correlation between seasonal variations of saline dust with meteorological parameters showed that increasing the salinity of the origin soil that occurs due to low precipitation and high temperature close to the loading of salt from the soil surface by wind. Indeed, Precipitation has contributed to a portion of soil moisture and increased adhesion between particles in reducing the removal of solutes with dust.

Hydrologic drought in the sense of deficient river flow is defined as the periods that river flow does not meet the needs of planned programs for system management. Drought is generally considered as periods with insignificant precipitation, soil moisture and water resources for sustaining and supplying the socioeconomic activities of a region. Thus, it is difficult to give a universal definition of drought. The most well-known classification of droughts is based on the nature of the water deficit: (a) the meteorological drought, (b) the hydrological drought, (c) the agricultural drought, (d) the socio-economic drought. Perhaps the most widely used model is the ARIMA model for predicting drought. The two general forms of ARIMA models are non-seasonal ARIMA (p, d, q) and multiplicative seasonal ARIMA (p, d, q) × (P, D, Q) in which p and q are non-seasonal autoregressive and moving average, P and Q are seasonal autoregressive and moving average parameters, respectively. The other two parameters, d and D, are required differencing used to make the series stationary. The differencing operator that is usually used in the case of non-stationary time series.
The aim of the study is to predict hydrological drought using time series analysis in the small forest watershed.

MATERIAL AND METHODS: Monthly discharge of Nahrkhoran hydrometric station (53 58 02E, 36 43 02N) during 1980-1981 to 2010-2011 located in Gharasoo watershed, Iran were collected from Company of Water Resources Management of Iran.
The present study was carried out using Box and Jenkins (1976) modeling approach. This approach involves the following three steps:Step 1-Model identification
In this step, the model that seems to represent the behavior of the series is searched, by the means of autocorrelation function (ACF) and partial autocorrelation function (PACF), for further investigation and parameter estimation. The behavior of ACF and PACF, is to see whether the series is stationary or not, seasonal or non-seasonal. Differencing is done to make non-stationary time series to stationary time series.
Step 2-Parameter estimation
After identifying models, we need to obtain efficient estimates of the parameters. These parameters should satisfy two conditions namely stationary and invertibility for autoregressive and moving average models, respectively. The parameters should also be tested whether they are statistically significant or not. Associated with parameters value are standard errors of estimate and related t-values.
Step 3-Goodness-of-fit test
Goodness-of-fit tests verify the validity of the model by some tools. The residuals of the model are usually considered to be time-independent and normally distributed over time. The most common tests applied to test time-independence and normality are the Mann-Kendall of test, the non-parametric Kolmogorov–Smirnov test.
Model calibration
In order to evaluate the accuracy of the streamflow forecasts obtained by applying the fitted model, Nash-Sutcliff (NS) coefficient of efficiency, root mean square error (RMSE), P-value of Wilcox and determination coefficient (R2) were used.
Drought definitions and thresholds
A drought is defined as an uninterrupted sequence of streamflow below an arbitrary level. Thus the mean and median value of streamflow time series is selected as the first truncation level. In the present study, as the monthly streamflow time series is applied for drought forecasting, the monthly mean and median values are also applied as the truncation level for each month. The two above truncation levels, we apply two other drought indices called standardized streamflow index (SSFI) and a probabilistic index which is based on hydrologic drought return periods. The SSFI for a given period is defined as the difference of streamflow from mean divided to standard deviation. A multiplicative seasonal autoregressive integrated moving average (SARIMA) model was applied to the monthly streamflow forecasting of the Naharkhoran River. In the first step of model identification, the ACF and PACF of the actual data and nonparametric Mann-Kendall test indicate the need of differencing. The Q–Q plot of the main series does not show normality. Thus, the logarithmic transformation was applied. The transformed Q–Q plot shows that the new series is normal. Based on Autocorrelation (ACF) and Partial Autocorrelation Functions (PACF) and results of Mann-Kendall test, SARIMA (1, 1, 1) * (0, 1, 1) 12 was selected. For testing the validity of SARIMA (1, 1, 1) * (0, 1, 1) 12 model for forecasting, the model is used for forecasting 10-, 9-, 5-, 3-, 2- and 1-year monthly streamflow. The present study result demonstrates the performance of time series models for 5-year period forecasting during October 2005 to September 2010.
The selected SARIMA model was then used to forecast streamflow from October, 1980 to September, 2011. The forecasted and observed flow rates are compared first with three truncation levels, which are SSFI, time series mean and median. The results showed that when SSFI is as truncation level, the selected model has not the ability to forecast drought. But when time series mean and median are as truncation level, the ability of the selected model is clear to forecast drought. Hydrologic drought frequency analysis was applied as an alternative truncation level for drought forecasting. Different frequency distributions were fitted to monthly streamflow and the flow rate for hydrologic drought in different 2-, 5-, 10- and 20-year return periods were estimated using maximum likelihood method of quantile estimation. The SARIMA model predict drought and humid periods as well. Due to the important role of drought forecasting in water resources management, a multiplicative seasonal autoregressive integrated moving average (SARIMA) model was applied to the monthly streamflow forecasting of the Naharkhoran River located in Gharasoo watershed, Iran. After normality examination of streamflow data, nonparametric Mann-Kendall test was used to detect trend analysis of data at confidence level of 95%. Based on ACF and PACF and results of Mann-Kendall test, SARIMA (1, 1, 1) * (0, 1, 1) 12 was selected. Mean and median streamflow as constant threshold and SSFI and drought frequency analysis in different return periods as variable threshold were used for determining drought periods. The present study result demonstrates the performance of time series models for 5-year period forecasting during October 2005 to September 2010. These models can be applied in water resources management.

The increase in population and need for food has resulted in the development of agricultural lands and pressure on aquifers, which has led to a sharp decline in the quantity and quality of groundwater resources. In many countries, especially in arid and semi-arid regions, in which the average annual precipitation is not adequate to support water requirements, groundwater is commonly used for agriculture, drinking and industry causing water crisis as a major dilemma. Groundwater quality is one of the most important factors in maintaining stability of aquifers and sustainability of groundwater resources means their exploitation and use in such a way that they do not seek quantitative and qualitative vulnerabilities and surrounding ecosystems. The qualitative and quantitative analysis of water resources is one of the most important evaluation approaches needed in this case. Azna- Aligudarz basin with an area of 2116.8 square kilometers is located in the western part of Iran and in the east of Lorestan province. The purpose of this research is to assess the quantitative and qualitative characteristics of groundwater in this area. First, the spatial and temporal fluctuations in groundwater level during the study period were assessed. Then for the seasons of recharge and discharge of aquifer during the study period (2004-2014), changes in physicochemical characteristics, the most important aquifer parameters for agricultural use based on Wilcox and California classification, the governing mechanism of water quality, type and hydrochemical facies of groundwater was analyzed. The findings showed that the water table of aquifer reduction was 10.45 cm. Average annual loss in the recharge season is equivalent to 83.7 cm during the statistical period, and 12.27 cm the annual drop in the discharge season or 98.16 cm during the study period. In general, groundwater level decreased by 1.33 meters over water years (2004-2014), affecting most of the south-west side of the basin. According to the results of physicochemical properties of water, concentration of most parameters changes has been incremental. Even, the parameter changes for TDS, CO3, Ca and Mg was more evident. The results of the California classification also showed that more than 55% of the area in terms of EC, TDS and SAR is in the unchanged range. According to the Wilcox diagram, the water quality is mostly in the S1C2 class (low salinity and alkalinity). Based on hydrochemical diagrams, it was determined that the main type and hydrochemical facies of water are Bicarbonate type and Calcic facies. The Gibbs graph also expresses the interactions between rock and water and weathering of minerals as the main determinant of water quality mechanism in the region. Discussion and conclusion: The results indicate that uncontrolled water withdrawal over the last ten years has led to the greatest decline in the quantity and quality of groundwater in the south-western part of the basin and is moving forward to the surrounding lands. Also, one of the factors reducing the water level during the study period is the excessive withdrawal of water during the discharge season. The highest increase in water quality levels has also occurred in the south-western part of the basin, which is more evident in the discharge season than in the aquifer recharge period. The results indicate that HCO3, Ca and Mg have the highest frequency in groundwater than other factors. Moreover, the main type of groundwater is bicarbonate with Calcic facies which is considered as heavy water and creates an almost corrosive state in industry.

Carbon stored in soils particularly in arid rangelands soils is the most significant carbon sink in terrestrial ecosystems. In arid rangelands, Soils have special places in both carbon sequestration and mitigate global warming. Therefore, any small change in the soil organic carbon (SOC) leads to a significant impact on the CO2 concentration in the atmosphere. Studies have shown that the climate change alters soil temperature and moisture conditions and subsequently affects soil respiration and carbon dioxide emitted from it into the atmosphere. Arid rangelands of Iran have taken a large part of the country. Modeling the effect of climate change on CO2 emissions from soil in arid rangelands is an essential management solution that potentially leads to the reduction of the CO2 emissions and the mitigation of its impacts on the climate change and global warming. Since evaluating the impacts of climate change on soil CO2 emission in long-term is difficult without the use of a modeling tool. Moreover, studying of soil CO2 emission under present or projected future scenarios of climate change through the use of simulation models is useful as decision support system. The primary purposes of this study were: 1) evaluating the performance of the RothC model simulations with the measured SOC stocks which is the most widely used model in the soil carbon studies and soil CO2 emissions and 2) determining the impacts of three different climate change scenarios on soil CO2 emissions in the arid rangelands of Ghir-o-Karzin’s BandBast in south of Iran. In this study, 80 soil samples were collected by randomized sampling method during four successive months (April to July of 2014) from a depth of 0-20 cm of soil. Also, two cylinders were collected beside each soil puddle (160 samples) for determining the soil bulk density in the arid rangelands of BandBast. After that, soil texture, soil bulk density, and soil organic carbon were measured by the Hydrometry method, the Core method and Walkley and Black method, respectively. Then, soil organic carbon (SOC) stock at depth of 0-20 cm was calculated. Initialization, calibrating and validating of the RothC model were performed by the use of weather data for 32 years as well as site-specific data (soil and plant data) of arid rangelands of BandBast. Finally, the effect of three climate scenarios on soil cumulative CO2 emissions and soil real CO2 emissions was simulated in the case study. Climate scenarios were including P scenario (refers to the ‘no climate change’ conditions or present climate condition consisted of the average monthly precipitation and mean monthly temperature during the period of 1983 to 2014), CCH1 scenario (refers to the climate change conditions with projected annual precipitation and the mean annual temperature decreased by 6.69% and increased by 9.96%, respectively) and CCH2 scenario (refers to the climate change conditions but with further decreases in rainfall and increase in temperature compared to the scenario CCH1 and also with projected annual precipitation and the mean annual temperature decreased by 10.93% and increased by 12.53%, respectively). Statistical comparisons between the simulated and measured data such as determination factor (R2= 0.76) and performance efficiency (PE= 0.69), shows that RothC model accurately simulated the SOC stocks and therefore can be employed to simulate CO2 emissions from soils in the arid rangelands of BandBast. The simulation results of RothC model during 36 showed that the cumulative and real values of CO2 emissions from soil to atmosphere would increase by 3.62 and 4.53%; and 3.15 and 3.78% under CCH1 and CCH2 scenarios, respectively compared to P scenario. In the CCH2 scenario, With the highest increase in temperature and the highest decrease of precipitation in soil CO2 emissions (cumulative and real) was higher in comparison with a CCH1 scenario. Result also showed that the trends of the soil real CO2 emissions in arid rangelands of BandBast would decrease under the climate change scenarios (CCH1 and CCH2) during 36 years (2014–2050 period). Discussion and Conclusion: Generally, the simulation results of the model showed an increasing trend for the CO2 emissions for future climate change scenarios (CCH1 and CCH2) in comparison with P scenario in the arid rangelands of Ghir VA Karzin’s BandBast. Climate change with decreasing annual precipitation and increasing temperatures have a significant effect on SOC and its decomposition and might enhance the release of CO2 from soil to the atmosphere. The trends of the real CO2 emissions from soil decreased in both climate change scenarios (CCH1 and CCH2) during 36 years. Based on recent researches soil carbon pools will be resistant against further decomposition over time and it could be due to existing dehumification effect. Therefore, investigate of organic mineral complex and humus complex compounds in the soils of BandBast rangelands is recommended for future researches.