nassim shabani; Mostafa Tarkesh Esfahani; Alireza Rajabi Mazhar; Nafiseh Salahi Moghadam; Peyman Akbarzadeh; Hasan Shadman; Mehdi Khoshbakht
Volume 32, Issue 2 , July 2025, , Pages 185-200
Abstract
Background and ObjectiveClimate change is recognized as one of the serious threats to biodiversity in natural ecosystems, having major impacts on the survival, performance, and distribution of plant and animal species. These changes can lead to alterations in population rates, species extinction, and ...
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Background and ObjectiveClimate change is recognized as one of the serious threats to biodiversity in natural ecosystems, having major impacts on the survival, performance, and distribution of plant and animal species. These changes can lead to alterations in population rates, species extinction, and shifts in the distribution of plant habitats. Therefore, a precise understanding of the climatic niche of species and the prediction of their responses to climate change are essential for natural resource management. Species distribution models (SDMs) are useful tools for predicting habitat changes and assessing the future impacts of climate change. In this study, the performance of three species distribution models, including the Maximum Entropy Model (Maxent), Ecological Niche Factor Analysis (ENFA), and Non-Parametric Multiplicative Regression (NPMR), is compared. The effect of climate change on the distribution of the habitat of Astragalus adscendens is analyzed for the years 2050 and 2100 under the HadGEM-RCP 4.5 scenario using the best-performing model. Materials and MethodsIsfahan Province, covering an area of over 107,000 square kilometers, has a wide range of elevations (707 meters to about 4000 meters) and diverse climatic zones (semi-arid, steppe, semi-steppe, dry forests, and high mountains). The plant species Astragalus adscendens is recognized as a native and significant species of the Iranian rangelands. To model the distribution of this species, 70 presence sites and 70 absence sites were randomly extracted from the vegetation type map of Isfahan Province using a stratified sampling method (Feizi et al., 2017). Additionally, 70 new sites were sampled through field visits in the towns of Semirom and Fereydunshahr using a GPS device for model evaluation data. A total of 22 environmental layers were prepared, including three physiographic variables (slope, aspect, and elevation) and nineteen bioclimatic variables for the present, 2050, and 2100 under the RCP 4.5 climate scenario using the HadGEM2 general circulation model. These variables are derived from three main parameters: monthly precipitation, minimum monthly temperature, and maximum monthly temperature. All environmental layers were prepared with a pixel size of one square kilometer. Finally, three modeling methods Maxent, ENFA and NPMR—were used to predict the distribution of Astragalus adscendens. ResultsAll three models showed good performance for predicting the habitat of Astragalus adscendens (AUC > 0.85). A reduction in habitat area under the HadGEM-RCP 4.5 climate change scenario is evident in all three models. Annual precipitation was identified as the most significant environmental factor influencing the distribution of Astragalus adscendens. Species response curves for the environmental variables, extracted from the Maxent and NPMR models, suggest that Astragalus adscendens is more prevalent in areas with precipitation over 350 mm and elevations above 2500 meters. The response curve of the species to slope indicates a positive relationship, showing that the likelihood of species presence increases with slope. Based on model evaluation, the Maxent model outperforms the others, showing a higher AUC index. ConclusionClimate change, particularly reduced precipitation and increased temperatures, will have significant negative effects on the distribution of Astragalus adscendens, such that by 2100, the presence of this species in Isfahan Province, especially in the Fereydunshahr region (western part of the province), will severely decrease. It will only be found in patches in the high elevations of Padanah in the Semirom region. It should be noted that the species distribution models used in this study considered only climatic and topographic conditions, without accounting for other influencing factors such as soil properties, management practices, and biological interactions. Therefore, the results presented can provide a general estimate of the potential distribution of the species under the HadGEM-RCP 4.5 climate scenario, but for more accurate habitat management, further studies incorporating other environmental and biological factors are essential.
Abbas kianipour; Amrali Shahmoradi
Volume 11, Issue 1 , September 2019, , Pages 1-18
Mohammad hosein parsamehr; zahra khoravani
Volume 24, Issue 1 , May 2017, , Pages 16-29
Abstract
This research was aimed to classify the drought in arid and semi arid regions of Isfahan province using TOPSIS technique. Four climatic elements including temperature, number of rainy days, annual rainfall and relative humidity were used for five meteorological stations during the 20-year period (1994-2013). ...
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This research was aimed to classify the drought in arid and semi arid regions of Isfahan province using TOPSIS technique. Four climatic elements including temperature, number of rainy days, annual rainfall and relative humidity were used for five meteorological stations during the 20-year period (1994-2013). For validation of the proposed method, the output of TOPSIS method was compared with the output of DPI, PNPI, RAI and SPI. For this purpose, Spearman's rank correlation coefficient was used between the quantified values of drought severity index and annual rainfall. The results showed that there was a strong correlation between the drought severity index and annual rainfall in the TOPSIS algorithm in all studied stations. Therefore, the validity of the model was approved. Generally, moisture fluctuations are high in the study area. In other words, drought is completely independent from station to station and from year to year, so that Nain and Isfahan had the highest (13 years) and lowest (7 years) number of drought years, respectively. In the TOPSIS algorithm, drought is closer to its real value since more parameters are used compared with previous simple methods. In this method, there is a systematic relationship between climatic elements in a year and other years, through which evaluation and ranking of drought is carried out. Finally, it could be concluded that the TOPSIS algorithm is a method capable of determining and ranking drought.
Mohammadreza Ekhtesasi; Asghar Zare chahouki
Volume 23, Issue 2 , September 2016, , Pages 264-255
Abstract
Estimating the amount of wind erosion in the plains of Iran is the most important requirement for planning and selecting appropriate methods of erosion control. Two approaches including IRIFR1 Model and wind erosion meter were used to measure and estimate the erosion and deposition potential in the Segzi ...
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Estimating the amount of wind erosion in the plains of Iran is the most important requirement for planning and selecting appropriate methods of erosion control. Two approaches including IRIFR1 Model and wind erosion meter were used to measure and estimate the erosion and deposition potential in the Segzi plain of Esfahan. Initially, different landforms of the Segzi plain including coarse grain plain, medium grain plain, and fine grain plain were detected. In order to measure the deposition potential, initially in each of the landforms per different wind speeds, the amount of soil erosion was measured within an hour using the wind erosion meter. The continuity of wind blowing for each wind speed class was estimated by analyzing the wind roses of East Isfahan station during the year. Finally, the erodibility rate of each landform was determined by integrating the multiplication of the continuity of each wind speed class and erodibility. In order to use the IRIFR1model, while visiting the desert, the scores of each index were given to the landforms and the deposition potential was estimated. The results showed that the amount of wind erosion of each studied landforms from coarse reg, average reg, fine reg and very fine reg were 2, 13.2, 21.3 and 74.1 ton/ha/yr, respectively. On the other hand, the values obtained from both models show differences of 5% to 30% in different landforms. The average amount of deposition obtained from IRIFR1 is about 11% less than the values obtained from wind erosion meter.
Mostafa saeedfar; Mohammad taghi Feyzi; Amr ali Shahmoradi
Volume 13, Issue 2 , February 2006, , Pages 116-126
Abstract
To manage renewable natural resources is impossible, without attention to its ecological characteristic. Therefore study of rangeland species autecology is very importance. In this research, the autecology of Salsola orientalis S.G.Gamelin was studied from 1997 to 1999 in Isfahan province (Mouthe). Thus ...
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To manage renewable natural resources is impossible, without attention to its ecological characteristic. Therefore study of rangeland species autecology is very importance. In this research, the autecology of Salsola orientalis S.G.Gamelin was studied from 1997 to 1999 in Isfahan province (Mouthe). Thus several factors as, geographical distribution, botanical characteristics, phenology, reproduction, seed rate, root system, chemical composition, nutrient value, forage production, disease, climate and its effects on this species were surveyed. This species has wide geographic distribution in the arid land of the world and appear in different vegetation types, also it is dominant in some of the sites in steppe region. This specimen has wide range of altitude from 1000 – 2000 m in Iran and 800 – 2000 m. in Esfahan province. This species is a shrub with 30 – 100 cm. high and in certain regions maybe reach to 1.5 m. Its phenological phenomens occur during long time and is different in different years. Chemical composition showed high protein (% 12), total digestible nutrient (TDN) 62%. Forage production is different according in ecological condition. Salsola orientalis was found in different soils (with different structure and texture) and geologic formation. It is resistant to pests and disease and heavy grazing. This species appears in regions up to 150 mm precipitation and with absolute maximum and minimum temperature, respectively +40 and -20 degree centigrade. For escaping from unsuitable condition it removes it's foliage and modifying growth period length and by this method resistant to aridity