azadeh bazrmanesh; Mostafa Tarkesh; Hossein Bashari; Saeid Poormanafi
Abstract
In order to model the potential habitat of Bromus tomentellus Boiss and study the effect of climate change on the habitat of this species in Isfahan province method of modeling maximum entropy (MAXENT) were used. The species event data were determined by random categorization method using field visits ...
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In order to model the potential habitat of Bromus tomentellus Boiss and study the effect of climate change on the habitat of this species in Isfahan province method of modeling maximum entropy (MAXENT) were used. The species event data were determined by random categorization method using field visits and geographic information system including 60 rangeland locations as educational points. Also, 20 points of occurrence were surveyed using GPS in the western region of Isfahan as points of assessment. 22 environmental layers including 3 physiographic variables and 19 climate variables derived from temperature and rainfall were used in the modeling process. Using by Maxent, the relationship between species incidence and environmental factors was determined. Then, the effect of climate change using cluster variables of CCSM4 general circulation model was evaluated under two scenarios RCP2.6 (optimistic) and RCP8.5 (pessimistic) on geographic distribution of Br.tomentellus Boiss. Regarding the photo curves, the specie’s behavior relative to the environmental variables of Br.tomentellus Boiss in the range of 2500 to 3500 altitudes, slope 10 to 30 degrees, annual precipitation is 240 to 260 mm and the average temperature is 8 to 10 ° C are more likely to occur. The habitat of the species studied during the two periods of 2050 and 2070, it was observed that under the optimistic scenario, 46.1 square kilometers to the appropriate level of the habitat of the Br.tomentellus Boiss is increased and under a pessimistic scenario, about 35.74 km2 is reduced from the appropriate level of habitat of this species.
Mahsa Ghazimoradi; Mostafa Tarkesh; Hossein Bashari; Mohammad Reza Vahabi
Abstract
In this study, the ability of Generalized Additive Model (GAM) for mapping potential distribution of Ferula ovina Boiss, and the description of species response curves to environmental variables were examined in Fereidonshar region with area of 1000 square kilometers located in West of Isfahan province. ...
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In this study, the ability of Generalized Additive Model (GAM) for mapping potential distribution of Ferula ovina Boiss, and the description of species response curves to environmental variables were examined in Fereidonshar region with area of 1000 square kilometers located in West of Isfahan province. The presence and absence data of the species were collected from 278 sites (including 138 presence sites and 140 absence sites) by random systematic method, and 9 soil variables, 22 climate variables and 3 physiographic variables were mapped with pixel size of 72*72 square meters by using interpolation techniques (krigging, Inverse Distance Weighting) for the entire studied area. Then, the relationships between presence and absence of the species with the environmental variables were examined by GAM method. According to the results, the presence of Ferula ovina was inversely correlated with some environmental variables including soil silt and clay contents and also its distribution was directly correlated with slope, distance from sea level, organic matter content, soil saturation percentage and average annual temperature. The model evaluation conducted by the separate data gave Kappa coefficient equal to 0.64 and ROC area under curve equal to 0.86. According to the produced potential habitat map and the response curves of the species, the presence of Ferula ovina is more likely in the habitats with mean annual temperature: 9-11 degree centigrade, slop: 25-50%, elevation: 1950-3000 meter (Above sea level), CaCO3 content of soil: 10-30%, organic matter: 4-6%, silt: 10-30% and soil saturation percentage: 45-60%. The GAM enables managers to identify appropriate areas for rangelands rehabilitation and protection programs. The produced model has a suitable performance in identifying regions with high growth potential and rangelands rehabilitation and protection programs.
Nima Shakeri boroujeni; Hossein Bashari; Mostafa Tarkesh esfahani
Abstract
This study sought to develop a Decision Support System (DSS) for assisting range managers todetect range condition and make informed decisions about Feridan County rangelands. All plantspecies frequencies were measured in 31 range sites with various grazing histories using step pointmethod. Four hundred ...
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This study sought to develop a Decision Support System (DSS) for assisting range managers todetect range condition and make informed decisions about Feridan County rangelands. All plantspecies frequencies were measured in 31 range sites with various grazing histories using step pointmethod. Four hundred points along four perpendiculars 30 meters transects were measured in eachsite and grazing indicator species were identified using grazing gradient analysis. The rangeconditions of the sites were determined by evaluating the frequencies of indicator species alonggrazing gradient using Resource Environment Data Information System (REDIS). The bestmanagement practices and ecological interpretation for each range condition classes were theninserted into the REDIS model. The end users can import the indicator species frequencies of aselected site into the REDIS model and obtain the required information about range condition class,ecological information and management options. According to the results, the frequencies of sixrange species in the study area can appropriately determine range condition classes quantitatively.The model performance was then evaluated by comparing the range condition classes of 12independent sites by REDIS model and ‘Four Factors’ method. The REDIS model had an accuracyof 91 percent. The mangers can save the condition position of a selected site along a conditiongradient in REDIS model; hence they could simply monitor the range condition changes of thestudied site.
Hossein Bashari; Mostafa Tarkesh; Tayebeh Shahabadi; Mohammad Reza Mosadeghi
Abstract
Abstract
This study aimed to investigate the effects of urban wastewater on some soil physical and chemical properties in Segzi, East Isfahan. Six sites were selected considering the planted species (Haloxylon persicum and Nitraria schoberi) and irrigation types (control or no irrigation, water logged ...
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Abstract
This study aimed to investigate the effects of urban wastewater on some soil physical and chemical properties in Segzi, East Isfahan. Six sites were selected considering the planted species (Haloxylon persicum and Nitraria schoberi) and irrigation types (control or no irrigation, water logged and furrow irrigation methods). The 4 to 12 replications were chosen in each site depending on its' size. Soil samples were collected in all replications from the 0‒10 and 10‒30 cm layers. Soil properties such as texture, organic matter, acidity, electrical conductivity, total soluble sodium, calcium and magnesium concentrations, and structural stability (dispersible clay) were measured for 94 collected soil samples. One-way ANOVA, Duncan's mean test and Principal Component Analysis were used to analyze and interpret the data. The results showed that wastewater affected some soil properties by leaching soluble salts into deeper soil horizons and also adding organic matter and some minerals into the soil. Electrical conductivities of the 0‒10 cm layer in control sites (no irrigation) and the 10‒30 cm layer in sites with furrow irrigation method were significantly greater than water-logged irrigated sites (α= 0.05). Applying wastewater increased soil organic matter content and aggregate stability significantly (α= 0.05). Irrigating the sites with wastewater decreased soluble sodium contents and dispersible clay of the soil surfaces; hence the soil structural stability was increased. Overall, applying wastewater to irrigate the planted seedlings in rangeland restoration projects has benefits as its use in these areas has lower environmental risk when compared with agricultural fields.
E Ghehsareh Ardestani; M Bassiri; M Tarkesh; M Borhani
Volume 63, Issue 3 , December 2010, , Pages 387-397
Abstract
Our planet is threatened by nuclear wars, climate change and degradation of biodiversity. The first two dangers are relatively focused on, but biodiversity degradation is not properly considered yet. Species diversity is mostly composed of biodiversity and is considered an index of changes in ecosystems. ...
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Our planet is threatened by nuclear wars, climate change and degradation of biodiversity. The first two dangers are relatively focused on, but biodiversity degradation is not properly considered yet. Species diversity is mostly composed of biodiversity and is considered an index of changes in ecosystems. Many of researchers think of higher species diversity as an index of bio-system’s stability. This research aimed to study parametric models of species diversity on range vegetations of study sites and relationship of ecological factors such as climate, soil and topography with diversity index. Four range sites were selected on different geographic areas in Isfahan province and randomly- systematic sampling was conducted to collect density data on plant species by quadrates along transects of each site during six years (2002-2007). Broken stick, log normal, logarithmic series and geometric series models were fitted for each site, and log normal showed to be the most proper model of distribution with P>0.05. LSD’s test indicated a significant different at ?=1% level between species diversity of steppe1 and semi-steppe2 sites. Log normal model seemed to be the most proper model in all sites. Generally, when this model is fitted successfully communities are considered stable. On the basis of some related studies with this research, Hill ( ) showed to be most proper index for species diversity in study sites, therefore effects of ecological factors such as soil, climate and topography on this index were studied by CCA method. Results of CCA revealed a high positive correlation between species diversity and percent organic matters of soil as well as precipitation levels and negative correlation with temperature.
