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| 1 | Potential habitat modeling for reintroduction of three native plant species in central Iran显示文摘Potential habitat modeling of endemic species is an appropriate method to maintain biodiversity,ecosystem function and rehabilitation of rangeland ecosystems.Astragalus caragana,A.cyclophyllon and A.podolobus are endemic in Iran's rangelands and some neighboring countries.The three native species could endure environmental stresses due to their distinctive ecophysiological characteristics.They play important roles in sustainable pastures production,recreation and improvement.They suffer severe threat from many factors including;grazing,agriculture and invasive exotic species.We analyzed the potential habitat of three native plant species in central Iran basing on the grid map with the resolution of 1-km.We used inventory records from field surveys,herbarium collections and 22 environmental factors to explore the environmental influences on given species distribution by Maximum entropy(Maxent) model.Maxent is a species distribution model that uses species occurrence and environmental data for predicting potential species.The results of our study indicated species occurrence has strong correlation with environmental factors such as mean temperature of wettest season,elevation and precipitation of coldest season.We evaluated the model accuracy by AUC(area under the receiver operating characteristic curve) based on an independent test data set.AUC values indicated the high power of Maxent to create potential habitat map(AUCA.caragana=0.988,AUCA.cyclophyllon=0.927,AUCA.podolobus=0.923).It is important to consider that AUC values tend to be lower for species that have broad distribution scope,such as A.podolobus distribution.Most suitable potential habitat distributions of the three species were predicted in the western and southwestern parts of rangelands in Isfahan province.Visual comparisons of the actual distribution map of the three species with produced Maxent maps represent a good agreement.In general,the model demonstrated that the occurrence of the given species is highly probable when the elevation is between 2,200 and 3,000 m and mean temperature of wettest season less than 3°C.This model,therefore,can be applied to recognize potential sites for rangeland reclamation projects. | Elham G ARDESTANI Mostafa TARKESH Mehdi BASSIRI Mohammad R VAHABI | 2015 | Journal of Arid Land2015，7，3： | 5 |
| 2 | Investigation of rangeland indicator species using parametric and non-parametric methods in hilly landscapes of central Iran显示文摘This study aimed to identify indicator species and explore the most important environmental and management variables contributing to vegetation distribution in a hilly upper dam landscape in Zagros Mountain chain, Iran. A stratified random sampling method was used to collect topographic, edaphic, management and vegetation data. The density and cover percentage of perennial species were measured quantitatively. Indicator species were identified using the two-way indicator species analysis. Besides calculating physiognomic factors in sample sites, 24 soil samples were collected from 0 to 30 cm of soil depth and analyzed in terms of gravel percentage, texture, saturation moisture, organic matter, pH and electrical conductivity in saturation extract, lime percentage, soluble calcium and magnesium, available phosphorus, Cation Exchange Capacity(CEC) and soluble sodium and potassium. Multivariate techniques including Canonical Correspondence Analysis and Multi-Dimensional Scaling were used to explore the relationships of species with environmental and management variables. Seven plants were identified as indicator species due to being significantly correlated with management(grazing or non-grazing) and edaphic variables such as CEC, soil texture, pH, CaCO3 percentage and physiographic variable including slope, elevation, and convex and concave formations(p < 0.05). Overall, overgrazing and its subsequent effects on soil characteristics, loss of vegetation cover and trampling were found as the major causes of deterioration. Sustainable and integrated management practices such as the implementation of appropriate grazing systems were suggested to enhance soil quality and reduce the accelerated erosion in upper dam zones. | Asiyeh SHEIKHZADEH Hossein BASHARI Mostafa TARKESH ESFAHANI SayedHamid MATINKHAH Mohsen SOLEIMANI | 2019 | Journal of Mountain Science2019，16，6： | 1 |
| 3 | Evaluation of the efficiency of irrigation methods on the growth and survival of tree seedlings in an arid climate显示文摘Scarce and scattered precipitation in arid regions is detrimental for newly planted seedlings.It is essential to provide required water storage for seedlings in restoration projects in the first year of their establishment.The subsurface irrigation can be much more effective than the surface irrigation because of the regulation of water availability and reduction in water evaporation.We studied the effect of surface and subsurface irrigation methods on the growth and survival of four common tree species including heaven tree(Ailanthus altissima(Mill.)Swingle),China berry(Melia azedarach L.),white mulberry(Morus alba L.),and black locust(Robinia pseudoacacia L.)by installing underground clay reservoirs with different permeabilities in Isfahan City,Iran.Different amounts of animal manure and wheat straw were mixed with clay fraction and cooked in a pottery kiln at 900°C to produce reservoirs with different permeabilities.The experimental treatments consisting of irrigation and tree species were considered with a factorial arrangement in a completely randomized design with three replications in 2016 and 2017.Leaf water potential of seedlings,which is indirectly related to drought resistance,was measured by a portable pressure chamber.The results showed that saplings height,basal diameter,number of leaves,chlorophyll content and stomatal conductance were significantly(P<0.05)higher in the subsurface irrigation with low permeability than in the surface irrigation,but the number of branches of the studied species were not significantly(P>0.05)affected by the irrigation methods and different permeabilities of clay reservoirs.The clay reservoirs with low and medium permeabilities constantly provide better conditions for plant growth,and water with lower pressure and longer time intervals to the plant roots as compared with the reservoirs with high permeability.Analysis of variance of the data showed that year and interaction between year and permeability of reservoir had significant effects(P<0.05)on all growth parameters,except for the chlorophyll content.In addition,the highest percentage of survival was 100%associated with the subsurface irrigation and the control treatment had the lowest survival percentages of 60%,70%,80%and 100%for M.alba,M.azedarach,A.altissima and R.pseudoacacia,respectively.Finally,the values of leaf water potential showed that R.pseudoacacia was the most drought resistant species. | Zahra JAFARI SayedHamid MATINKHAH Mohammad R MOSADDEGHI Mostafa TARKESH | 2020 | Journal of Arid Land2020，12，3： | 1 |
| 4 | Interactions between vegetation dynamic and edaphic factors in the Great Salt Desert of central Iran显示文摘Investigating the relationships between vegetation dynamic and edaphic factors provide management insights into factors affecting the growth and establishment of plant species and vegetation communities in saline areas.The aim of this study was to assess the spatial variability of various vegetation communities in relation to edaphic factors in the Great Salt Desert,central Iran.Fifteen vegetation communities were identified using the physiognomy-floristic method.Coverage and density of vegetation communities were determined using the transect plot method.Forty soil samples were collected from major horizons of fifteen profiles in vegetation communities,and analyzed in terms of following soil physical and chemical characteristics:soil texture,soluble Na+concentration,sodium adsorption ratio(SAR),electrical conductivity(EC),pH,organic matter content,soluble Mg2+and Ca2+concentrations,carbonate and gypsum contents,and spontaneously-and mechanically-dispersible clay contents.Redundancy analysis was used to investigate the relationships between vegetation dynamic and edaphic factors.The generalized linear method(GLM)was used to find the plant species response curves against edaphic factors.Results showed that plant species responded differently to edaphic factors,in which soluble sodium concentration,EC,SAR,gypsum content and soil texture were identified as the most discriminative edaphic factors.The studied plant species were also found to have different ecological requirements and tolerance to edaphic factors,in which Tamarix aphylla and Halocnemum strobilaceum were identified as the most salt-resistant species in the region.Furthermore,the presence of Artemisia sieberi was highly related to soil sand and gypsum contents.The results implied that exploring the plant species response curves against edaphic factors can assist managers to lay out more appropriate restoration plans in similar arid areas. | Hossein BASHARI Seyed Mehrdad KAZEMI Soghra POODINEH Mohammad R MOSADDEGHI Mostafa TARKESH Seyed Mehdi ADNANI | 2021 | Journal of Arid Land2021，13，2： | 0 |
| 5 | Spatial downscaling of climate variables using three statistical methods in Central Iran显示文摘Spatial downscaling methods are widely used for the production of bioclimatic variables(e.g. temperature and precipitation) in studies related to species ecological niche and drainage basin management and planning. This study applied three different statistical methods, i.e. the moving window regression(MWR), nonparametric multiplicative regression(NPMR), and generalized linear model(GLM), to downscale the annual mean temperature(Bio1) and annual precipitation(Bio12) in central Iran from coarse scale(1 km × 1 km) to fine scale(250 m ×250 m). Elevation, aspect, distance from sea and normalized difference vegetation index(NDVI) were used as covariates to create downscaled bioclimatic variables. Model assessment was performed by comparing model outcomes with observational data from weather stations. Coefficients of determination(R2), bias, and root-mean-square error(RMSE) were used to evaluate models and covariates. The elevation could effectively justify the changes in bioclimatic factors related to temperature and precipitation. Allthree models could downscale the mean annual temperature data with similar R2, RMSE, and bias values. The MWR had the best performance and highest accuracy in downscaling annual precipitation(R2=0.70; RMSE=123.44). In general, the two nonparametric models, i.e. MWR and NPMR, can be reliably used for the downscaling of bioclimatic variables which have wide applications in species distribution modeling. | Zahra JABERALANSAR Mostafa TARKESH Mehdi BASSIRI | 2018 | Journal of Mountain Science2018，15，3： | 0 |
| 6 | Modelling the impact of climate change on rangeland forage production using a generalized regression neural network:a case study in Isfahan Province,Central Iran显示文摘Monitoring of rangeland forage production at specified spatial and temporal scales is necessary for grazing management and also for implementation of rehabilitation projects in rangelands. This study focused on the capability of a generalized regression neural network(GRNN) model combined with GIS techniques to explore the impact of climate change on rangeland forage production. Specifically, a dataset of 115 monitored records of forage production were collected from 16 rangeland sites during the period 1998–2007 in Isfahan Province, Central Iran. Neural network models were designed using the monitored forage production values and available environmental data(including climate and topography data), and the performance of each network model was assessed using the mean estimation error(MEE), model efficiency factor(MEF), and correlation coefficient(r). The best neural network model was then selected and further applied to predict the forage production of rangelands in the future(in 2030 and 2080) under A1 B climate change scenario using Hadley Centre coupled model. The present and future forage production maps were also produced. Rangeland forage production exhibited strong correlations with environmental factors, such as slope, elevation, aspect and annual temperature. The present forage production in the study area varied from 25.6 to 574.1 kg/hm^2. Under climate change scenario, the annual temperature was predicted to increase and the annual precipitation was predicted to decrease. The prediction maps of forage production in the future indicated that the area with low level of forage production(0–100 kg/hm^2) will increase while the areas with moderate, moderately high and high levels of forage production(≥100 kg/hm^2) will decrease both in 2030 and in 2080, which may be attributable to the increasing annual temperature and decreasing annual precipitation. It was predicted that forage production of rangelands will decrease in the next couple of decades, especially in the western and southern parts of Isfahan Province. These changes are more pronounced in elevations between 2200 and 2900 m. Therefore, rangeland managers have to cope with these changes by holistic management approaches through mitigation and human adaptations. | Zahra JABERALANSAR Mostafa TARKESH Mehdi BASSIRI Saeid POURMANAFI | 2017 | Journal of Arid Land2017，9，4： | 0 |
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