Negar Shamsaei; Rasoul Mahdavi; Asadolah khoorani; Hamid Gholami
Volume 32, Issue 3 , September 2025, Pages 211-231
Abstract
AbstractBackground and ObjectivesClimate change, especially changes in temperature and precipitation, is one of the most essential topics in environmental sciences. Due to its scientific and practical dimensions, including environmental and economic-social effects, climate change is increasingly important ...
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AbstractBackground and ObjectivesClimate change, especially changes in temperature and precipitation, is one of the most essential topics in environmental sciences. Due to its scientific and practical dimensions, including environmental and economic-social effects, climate change is increasingly important because human systems dependent on climatic elements such as water resources, agriculture, and industries are designed and operated based on climate stability. On the other hand, the impact of climate change on water resources is significant and requires further investigation. This impact is particularly concerning in arid and semi-arid regions like the southern parts of the country, especially Hormozgan Province. Therefore, when we can analyze the current climatic conditions in the region and predict the availability of water in the coming years, we can make more effective long-term decisions to sustainably utilize the province’s natural resources and prevent its ecological decline.MethodologyDue to its location on a dry belt and desert strip, Hormozgan province is faced with a fragile natural environmental ecosystem and climate conditions and long drought periods (Figure 1). Since the available potential water includes several parameters, it is considered a suitable indicator for the long-term study of climate change and desertification. Therefore, in this study, while evaluating various CMIP6 models, changes in temperature, precipitation, potential evapotranspiration, and available potential water index in two periods of the near future (2031-2060) and the far future (2071-2100) compared to the observation period (1993-2023) was investigated under shared socio-economic pathways o SSP2-4.5 and SSP5-8.5. In order to conduct this research, first, the daily temperature and precipitation data for the six study meteorological stations in the observation were obtained from http://data.irimo.ir. Also, the precipitation and average temperature output based on 14 CMIP6 models for the base period (1993-2014), the near future, and the far future were extracted from the ESGF database (Table 1). In the following, two shared socio-economic pathway scenarios were used: the SSP2-4.5, which considers the world with socio-economic development under normal conditions, with medium vulnerability and radiative forcing level, and also the SSP5-8.5, which considers the upper limit of fossil fuel consumption. The climate models were fine-scaled using the linear scaling bias correction (LSBC) for the temperature and the delta change factor (DCF) method for precipitation. To evaluate the performance of the models, RMSE, MSE, MAE, R, and R2 criteria were considered. Also, the IWM method was used to ensemble the selected models for better understanding and reducing uncertainty. Then, the changes in temperature, precipitation, potential evapotranspiration, and available potential water were predicted in the two future periods and compared with those in the observation period. The trend of changes in the available potential water index in these periods was also investigated using the non-parametric Mann-Kendall test and Sen’s slope estimator (table 4).ResultThe results showed that the ensemble of models exerted a suitable accuracy for simulating temperature and precipitation. The forecast results showed that the precipitation in the near future will decrease by 10 and 14.5% based on the SSP2-4.5 and SSP5-8.5 scenarios, respectively (Figure 3). In the far future, the precipitation will decrease by 5.5 and 32.6%, respectively, compared to the base period using such scenarios. In total, it is expected that the average precipitation will decrease by 12.2% in the near future period and 20.7% in the far future period in Hormozgan province. Meanwhile, the temperature will increase, and this increase in the near and far future periods will be 1.7 and 3.3 °C, respectively, compared to the observation period (Figure 4).ConclusionBased on this, the amount of potential evapotranspiration increases, while the amount of available potential water decreases. In the near future period, the rate of potential evapotranspiration and the shortage of available water will increase by an average of 5.02 and 8.9%, respectively. In the far future period, they will increase by 12.5 and 17.3%, respectively (Figure 6). Examining the time series of these variables also confirms the results. The findings of this research can be used as a strategic tool for policymakers and managers of water resources in Hormozgan province.
Hasan Ghelichnia; Alireza Eftekhari
Volume 32, Issue 3 , September 2025, Pages 232-254
Abstract
ABSTRACTBackground and objective The monitoring and evaluation of rangelands provides the necessary information for the basic planning of rangeland management and as a result prevents the destruction of rangelands and water and soil conservation. The goals of this research are to prepare a continuous ...
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ABSTRACTBackground and objective The monitoring and evaluation of rangelands provides the necessary information for the basic planning of rangeland management and as a result prevents the destruction of rangelands and water and soil conservation. The goals of this research are to prepare a continuous database of vegetation and soil indicators in rangelands and monitor their changes, determine the relationship between vegetation indicators and climatic factors, determine the trend and intensity of changes in different managements, and provide information for calculating long-term capacity of rangelands.Methodology For this study, the Polour site was selected in the rangelands of Baladeh region in Mazandaran province and was evaluated and monitored for 5 years. In order to evaluate the indicators of vegetation cover, 3 transects of 100 meters were placed at a distance of 50 meters from each other. Vegetation and soil factors were measured.Vegetation factors included canopy cover, density and production of plant species, litter, rangeland condition and trend. Soil factors include pH, EC, nitrogen, phosphorus, potassium, organic matter, soil bulk density and soil texture. 10 plots 1m2 were placed along each transect and a total of 30 plots in exclosure and grazed areas. The canopy cover of any plant species with the method of measuring the canopy surface, the density by counting the number of species, the production by cutting and weighing, and the percentage of stone and gravel cover, litter,the and the bare soil were also measured in the plots. Statistical analyses were done in Minitab16 software.Results The results of analysis of variance have shown that there is a significant difference between most of the vegetation factors in different years. There is a significant difference between all the investigated vegetation variables in exclosure and grazed areas. There is no significant difference between most of the investigated soil factors in different years, except for the organic matter under the plant. There is a significant difference between the percentage of nitrogen, phosphorus, potassium, organic carbon and organic matter in exclosure and grazed areas. The comparison of the averages of vegetation cover in different years shows that the highest average percentage of the total cover was related to exclosure area. The highest average value was related to the years 2020, 2021, 2018 and 2019, respectively, and the lowest was related to the year 2017. The correlation between the coverage percentage of the exclosure area with the total production, the percentage of nitrogen and organic matter under and outside the plant, electrical conductivity under the plant and the amount of rainfall in the growing season is significant. In the grazed area, there is a significant correlation between the coverage percentage of the exclosure area with total production, organic matter under and outside the plant, and rainfall during the growing season. Correlation between the total production in the grazed area with the percentage of total coverage, the percentage of nitrogen and organic matter under and outside the plant, electrical conductivity under the plant and the amount of rainfall in the growing season is significant.Conclusion There is a significant difference between the fexclosure and grazed areas in terms of some soil factors. There is a significant difference between the indicators of vegetation cover during the studied years. The highest amount of coverage and production in both exclosure and grazed areas was in 2021 and the lowest in 2017. The results of the correlation test showed that total rainfall, autumn and winter rainfall, and growing season rainfall had the highest correlation in the canopy cover and plant production.
Seyedeh Fatemeh Arab; Javad Bazrafshan
Volume 32, Issue 3 , September 2025, Pages 255-276
Abstract
AbstractBackground and ObjectivesDrought is typically characterized as a temporary deficit in water resources relative to normal regional conditions. This slow-onset phenomenon occurs across all climate zones but exhibits complex structures and region-specific impacts. Extreme droughts are distinguished ...
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AbstractBackground and ObjectivesDrought is typically characterized as a temporary deficit in water resources relative to normal regional conditions. This slow-onset phenomenon occurs across all climate zones but exhibits complex structures and region-specific impacts. Extreme droughts are distinguished by their intensity in severe or very severe classes. In drought research employing conventional indices, the identification of extreme droughts depends on analysis across different time scales. The concept of super-drought extends this framework by considering drought occurrences across multiple timescales, providing a broader perspective beyond extreme droughts. Identifying superdroughts involves statistical integration of drought signals at various time scales. International studies on superd-roughts—initiated nearly a decade ago—have significantly advanced our understanding of drought dynamics. This phenomenon is crucial as it reflects the prolonged impact of droughts on regional water and ecological systems. Consequently, this study seeks to explore the potential occurrence of super-droughts, analyze their characteristics, and assess their effects on vegetation, with Khuzestan Province serving as the study region.Materials and MethodsThis research utilizes daily meteorological data—including precipitation, temperature, relative humidity, wind speed, and sunshine hours—from five synoptic stations in Khuzestan Province: Ahvaz, Bandar Mahshahr, Masjed Soleyman, Safiabad Dezful, and Bostan, covering the period 1990–2019. Additionally, NDVI data obtained from the MODIS satellite (Terra sensor, product MOD13A3, spatial resolution of 1 km²) spanning 2000–2019 was analyzed. For each station, an 81-pixel region (9×9 grid) was selected, and the median NDVI value was calculated monthly to serve as the vegetation index. Following quality control and gap filling, the Standardized Precipitation-Evapotranspiration Index (SPEI) was computed across five time scales: 3, 6, 12, 24, and 48 months. Subsequently, the Composite Drought Index (CDI) was derived by applying the Vine copulas technique to these SPEI scales, a method capable of capturing the complex dependence structure among the indices. The relationship between CDI and NDVI was then statistically modeled at each station.ResultsFindings indicated that the Vine copulas method effectively analyzed the dependence across the five SPEI time scales. The resulting CDI enabled the identification of superdrought events within the study area. While some stations experienced similar drought periods, no singular dry spell was common across all five stations. For example, the most intense drought episodes were observed at Masjed Soleyman in December 2001, and at Ahvaz, Bandar Mahshahr, and Safiabad Dezful in various other years.The correlation between CDI and NDVI was predominantly positive and statistically significant throughout most months, with the highest correlations at Safiabad Dezful between February and April (r > 0.7). At Bostan, this positive relationship persisted nearly year-round. Notably, during the hotter months at Safiabad Dezful, a significant negative correlation emerged, indicating that heightened thermal stress can weaken vegetation even amidst drought conditions.ConclusionThe study demonstrates that the Vine ccopulas method, by integrating multi-scale SPEI data and accounting for their complex interdependencies, effectively identified superdrought events over a 30-year period at the selected stations. In contrast, a straightforward comparison of SPEI values across scales, without the Vine approach, revealed only a limited number of superdroughts, with Bostan’s station showing none. The CDI showed a strong correlation with NDVI, confirming its utility in detecting drought-related vegetation stress. Generally, increased drought intensity corresponded with decreased vegetation greenness, attributable to water deficits, although during certain hot months, vegetation greenness increased due to thermal stress effects. Future research should consider the sensitivity of CDI to the specific thresholds of drought occurrence, as well as its dependence on the underlying SPEI scales, to refine drought monitoring and ecological impact assessments.
Foruzan Fazelinejad Delfan; Reza Erfanzadeh; Samad Jamali
Volume 32, Issue 3 , September 2025, Pages 277-291
Abstract
AbstractBackground and Objectives Interactions between arbuscular mycorrhizal fungi (AMF) and plants are critical for ecosystem function; however, these interactions remain poorly characterized in mountainous and cold environments. This research aimed to ...
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AbstractBackground and Objectives Interactions between arbuscular mycorrhizal fungi (AMF) and plants are critical for ecosystem function; however, these interactions remain poorly characterized in mountainous and cold environments. This research aimed to investigate the effect of three shrub species (Berberis integerrima, Onobrychis cornuta, and Juniperus sabina.) on root colonization, spore population, and fungal species diversity in the rhizosphere of these plants.Materials and Methods This research was conducted in the Belde highlands, Helooposhteh village, in the southern part of Nur County, Mazandaran Province, Iran. A field survey was initially performed to select 13 plots as replicates. Each plot contained three adjacent shrub species. Soil sampling was carried out in the spring of 2023. A total of 52 rhizosphere soil samples (4 samples under each shrub and 1 sample from outside the shrub canopy in each plot) and 39 root samples were collected. Soil samples were taken from a depth of 0-30 cm in each of the 13 plots. Root samples were stained using the Hayman & Phillips (1970) method to visualize fungal structures (vesicles, arbuscules, and hyphae). Also, 200 grams of each soil sample were taken, and spores were isolated and counted using a washing, wet sieving, and centrifugation method in a sucrose solution. Then, identification was performed.ResultsThe results indicated that the diversity of arbuscular mycorrhizal fungi (AMF) was significantly influenced by the canopy of different shrub species. In the control (areas outside the shrub canopies), Diversispora aurantia was identified. Under the canopy of Onobrychis cornuta, Glomus flavisporum and Acaulospora sp. were found. Additionally, under the Berberis integerrima canopy, Gigaspora gigantea, Acaulospora colombiana, and Acaulospora jejuensis were identified, and under the Juniperus sabina canopy, Cetraspora pellucida and Glomus flavisporum were observed. The results also showed that Acaulospora had the highest abundance among these fungi, while Gigaspora and Diversispora aurantia had the lowest. Furthermore, root colonization rate and spore counts showed significant differences among the shrub species. The root colonization percentage for O. cornuta was 79.46% with a spore count of 4038 per 200g of soil The relative abundance of J. sabina was 53.46% (3952 spores), while B. integerrima constituted 41.30% (3593 spores) of the total spore count.ConclusionThe results of this study emphasize the significance of species diversity in shrub communities within mountainous and cold habitats, highlighting their pivotal role in shaping fungal communities and enhancing ecosystem functions. Shrubs are recognized as key drivers in ecological interactions and in maintaining the sustainability of ecosystem processes.
hamid Hosseinimarandi; Hamidreza Abbasi
Volume 32, Issue 3 , September 2025, Pages 292-312
Abstract
AbstractBackground and objectiveThe phenomenon of dust storms results from a combination of natural and human-induced factors and has serious impacts on health, agriculture, transportation, and water resources. Strong winds can detach fine particles from dry soils, leading to the formation of dust storms ...
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AbstractBackground and objectiveThe phenomenon of dust storms results from a combination of natural and human-induced factors and has serious impacts on health, agriculture, transportation, and water resources. Strong winds can detach fine particles from dry soils, leading to the formation of dust storms that transport these particles over long distances. Consequently, dust storms have become a local, regional, and global challenge. In southwestern Iran, the average number of dusty days over the past 50 years has ranged between 27 and 75 days per year. Due to its geographical and climatic conditions, Fars Province is affected by both internal and external dust sources. Land-use changes, consecutive droughts, and geological characteristics are among the key factors contributing to the expansion of this phenomenon. Considering the geological conditions of Fars Province, the presence of abandoned agricultural lands, the drying of wetlands, and land-use changes, the dust phenomenon holds particular significance. The objective of this study is to examine the distribution and introduce the physicochemical properties of surface soils in dust-producing areas through the analysis of land-use documents, meteorological and geological data, remote sensing, field visits, and laboratory investigations. Additionally, this research aims to provide a foundation for further studies and desertification control projects.Materials and methodsIn this study, dust source areas were identified and classified using maps of desert regions, geology, land use, and vegetation cover within a GIS environment. Sampling points were then determined using a 2×2 km grid method over these source areas. Two soil samples were collected from each point: a 2-kg sample from the 0 to 30 cm depth for physicochemical tests and a 20-kg sample for wind erosion testing. The physicochemical tests included measuring pH, electrical conductivity (ECe), ionic compositions, cation exchange capacity (CEC), saturated moisture percentage (SP), gypsum content, and soil texture. Additionally, a wind tunnel test was conducted to evaluate wind erosion. Finally, to examine the relationship between soil properties of the source areas and wind erosion, the data obtained were analyzed using charts and tables.ResultsFive major dust source areas have been identified in Fars Province, including Bakhtegan-Neyriz, Maharloo-Sarvestan, Shahrpir-Zarindasht, Dezhgah-Farashband, and Khonj-Larestan. These dust hotspots are located in the central, eastern, and southern parts of the province and are primarily affected by rangeland degradation, drought, and wetland desiccation. Land-use analysis in these areas indicates that 65% of the land consists of degraded rangelands, 19% comprises dried wetlands, and 16% includes abandoned agricultural lands and rainfed farms. The threshold wind erosion speed in these hotspots ranges between 8 and 10 meters per second. Moreover, the correlation between erosion intensity and increasing wind speed in most of these areas is between 80% and 99%, highlighting their high sensitivity to atmospheric changes and rising wind speeds.Wind tunnel experiments indicate that the highest wind erosion occurred in Dezhgah-Farashband, where at a wind speed of 25 meters per second, the erosion rate reached 15.76 kg per square meter per minute. The soil texture in these dust source areas mainly consists of loam, sandy loam, and loamy sand. The soil pH varies between 7.5 and 8.5, while electrical conductivity ranges from 0.41 to 157.7 dS/m. A correlation study between soil wind erosion and parameters such as salinity, acidity, sodium content, organic matter, and soil texture (sand, silt, clay) indicates a weak correlation between wind erosion and salinity, particularly in saline soils. However, in non-saline soils, a positive and significant correlation (66.7%) exists. Conversely, a positive and significant correlation is observed between wind erosion and sand content, while a negative correlation is found with silt and clay content.DiscussionThe study reveals that the wind erosion threshold velocity varies across different locations, primarily depending on the physical and chemical properties of the soil. In areas with coarser soil textures, and relatively higher silt proportions (e.g., the Dezhgah-Farashband dust resources), a lower wind speed is required to initiate wind erosion and transport soil particles; thus, the threshold wind erosion velocity is lower. Conversely, in areas with higher clay content and lower silt content (e.g., parts of the Khonj - Larestan and the Shahrpir-Zarindasht dust resources), a higher wind speed is necessary to initiate wind erosion. The wind erosion threshold velocity across all study ranged from 7 to 10 meters per second. The Dejgah-Farashband dust resource exhibits the highest dust production due to its soil composition. Conversely, the Shahrpir-Zarindasht dust resource is more resistant to wind erosion due to its heavier soil texture. Furthermore, increased soil salinity reduces particle cohesion, potentially lowering the wind erosion threshold velocity. This study indicates that soil salinity, pH, and organic matter content can influence both the wind erosion threshold velocity and dust production.ConclusionThe dust hotspots in Fars Province, including Neyriz-Bakhtegan, Maharloo-Sarvestan, Shahrpir-Zarindasht, Dezhgah-Farashband, and Khonj-Larestan, are influenced by a combination of environmental factors. The most significant of these include the drying of wetlands (particularly Bakhtegan, Abadeh Tashk, and Maharloo), extensive rangeland degradation, and unfavorable soil characteristics such as loamy texture, high salinity, and low organic carbon content. Although high wind speeds (with an erosion threshold of 8 to 10 m/s) play a crucial role in erosion within these areas, the extent of windborne sediment transport and dust production is significantly influenced by soil texture and the percentage of clay and silt. For instance, the Shahrpir-Zarindasht hotspot exhibits lower erosion due to its fine-grained soil texture. Therefore, a comprehensive and targeted management approach, focusing on wetland restoration, vegetation improvement, and soil rehabilitation, is essential to mitigate the adverse impacts of dust storms.
Hamed Joneidi; Shirko Ebrahimi Mohammadi; Roya Shadi
Volume 32, Issue 3 , September 2025, Pages 313-327
Abstract
The effect of oak biochar on some functional characteristics, soil fertility and essential oil yield of the medicinal plant Achillea millefolium L.Background: Several studies have shown the significant effect of biochar on improving the biological and functional characteristics of plants. In the present ...
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The effect of oak biochar on some functional characteristics, soil fertility and essential oil yield of the medicinal plant Achillea millefolium L.Background: Several studies have shown the significant effect of biochar on improving the biological and functional characteristics of plants. In the present study, the effects of oak biochar on some functional characteristics and efficiency of A.millefolium essential oil and physicochemical properties of soil was investigated. Materials and Methods: To conduct the study Oak biochar made during pyrolysis at temperatures of 300 and 500 (B300 and B500, respectively) degrees Celsius was also used in the treatment groups. Soil was divided into 45 pots, including 15 control pots, 15 pots with 300 degrees Celsius (B300) oak biochar, and 15 pots with 500 degrees Celsius (B500) biochar. The ratio of biochar to soil in this experiment was the same for both treatments and was considered equal to 5%. After the plant grew and reached the flowering stage, the values of total chlorophyll, chlorophyll a, chlorophyll b, dry weight of aboveground biomass, dry weight of root biomass and percentage of essential oil were measured in different control and treatment groups. Also, the properties of soil pH, soil EC, organic carbon and total soil nitrogen were measured in the treatments. In order to compare different soil and plant parameters among the treatments, one-way analysis of variance test was used. Results: The results showed that the addition of biochar significantly increased chlorophyll a (by 19%), total chlorophyll (by 17%), essential oil yield (by 36%), dry weight of aboveground biomass (by 25%), and dry weight of underground parts (by 87%) in the treatment groups compared to the control. Also, the addition of biochar significantly increased organic carbon (by 88%) and soil nitrogen (by 27%) in the biochar treatment groups compared to the control. No significant differences were observed between the B300 and B500 treatments in any of the plant and soil parameters. Conclusion: According to the results obtained from this study, the use of biochar is recommended as a suitable method for increasing the yield and production of essential oil, as well as improving the chemical quality and yield of soil. The results of the present study show that the process of producing oak biochar at a temperature of 300 degrees Celsius is effective in improving the yield of A. millefolium and increasing the efficiency of essential oil, and there is no need to increase the temperature to more than 300 degrees Celsius to produce biochar.