Document Type : Research Paper

Authors

• Mostafa Tarkesh ¹
• Nafiseh Monsef ²
• Mohammad Reza Vahabi ³
• Saeid Pourmanafi ⁴
• Mohaddeseh Amiri ^{5, 6}

¹ Associated Professor, Department of Range and Watershed Management, Faculty of Natural Resources, Isfahan University of Technology, Isfahan, Iran

² Department of Range and Watershed Management, Faculty of Natural Resources, Isfahan University of Technology, Isfahan, Iran

³ Associated Professor,, Department of Range and Watershed Management, Faculty of Natural Resources, Isfahan University of Technology, Isfahan, Iran

⁴ Assistant Professor, Environmental Sciences, Faculty of Natural Resources, Isfahan University of Technology, Isfahan, Iran

⁵ Researcher, Department of Range and Watershed Management, Faculty of Natural Resources, Isfahan University of Technology, Isfahan, Iran

⁶ Dept. of Agricultural Science, Technical and Vocational University, Tehran, I.R. of Iran.

Abstract

The distribution of plant species in ecosystems is not random but is influenced by environmental factors. The present study was conducted with the aim of investigating the effect of environmental factors on the distribution of Astragalus verus and its response to environmental gradients in western rangelands of Isfahan province. After recording the species presence/absence points, the NPMR model was used for the species’ habitat suitability modeling. For the soil variables that were normalized according to the type of skewness by data transformation, Kriging methods were used and for the variables with non-normal distribution, the IDW method was used to produce the map. The spatial continuity of these variables was checked by selecting the best fitted variogram model. The response curve to the important variables specified by LogB index indicated that the maximum presence of the species occurred in the precipitation of 110mm in the coldest season, the annual mean temperature of 11°C, and soils with neutral pH to slightly alkaline pH. Also, when the mean temperature of coldest season is -2°C, maximum temperature of warmest month is 33°C and the temperature seasonality is 9.2, the maximum presence of the species was observed. The performance of the model was reported to be excellent based on replacement method and the use of independent data method. By selecting the optimal threshold (52%) in the replacement method and creating a fuzzy suitability map, the species covers 30.72% of the area. Results can be used to improve and rehabilitate Astragalus habitats with similar ecological conditions.

Keywords

• ecology
• response curve
• interpolation
• environmental gradient
• NPMR model

Main Subjects

• Ecology