Document Type : Research Paper
Authors
1 Professor, Department of Reclamation of Arid and Mountainous Regions, Natural Resources Faculty, University of Tehran, Tehran, Iran
2 Former M.Sc. in Range Management, Department of Reclamation of Arid and Mountainous Regions, Natural Resources Faculty, University of Tehran, Iran
3 Professor, Department of Reclamation of Arid and Mountainous Regions, Natural Resources Faculty, University of Tehran, Iran
Abstract
The study was performed with the aim of modeling the distribution habitats of Eshtehard rangelands using Maximum Entropy Method and determining the factors affecting each habitat. Vegetation and environmental data including soil characteristics and topography were collected. The initial map was prepared based on slope, elevation and direction maps and satellite images. At each site, three transects with a length of 750 m were established, two transects along the most important environmental gradients and one transect perpendicular to them. A number of 45 plots along each transect was placed at a distance of 50 meters. The size of plot sampling was determined to be two square meters according to the type and distribution of plant species with minimal area method. Soil profiles were dug at the beginning and end of each transect. Sampling was done from the depths of 0-20 cm and 20-80 cm. The list of species and the percentage of vegetation in each plot were determined. For each sampling unit, the latitude and longitude data, slope, direction, and elevation were also determined. Then the desired characteristics were measured in the laboratory. GIS and Geostatistics methods were used to map the environmental variables. The species distribution models were produced using the species presence data and Maximum Entropy Method (Maxent). The Kappa coefficient index and the area under the curve (AUC) were used to evaluate the accuracy of the distribution maps. The agreements of actual and predicted maps for Pteropyrum olivieri was well (K=0/7) and it was acceptable for Halocnemum strobilaceum, Salsola richteri-Artemisia sieberi, Artemisia sieberi, Artemisia sieberi–Stipa barbata (K=0/66, 0/64, 0/57, 0/66).
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