Spatial modeling of the suitability of Astragalus podolobus habitat using Frequency Ratio

Abstract

Astragalus podolobus is a thorn less half-shrub plant that is considered as one of the most valuable species in the Iran rangelands. Land-use changes and rangelands degradation represent a real threat to it. To determine how to manage it better, the potential spatial distribution of this species was mapped using a bivariate statistical model (FR: frequency ratio) for the Maraveh Tapeh rangelands of Golestan province, north-east Iran. A total of 115 occurrences of A. podolobus were recorded using GPS during field surveys from April to September in 2018 and 2019, then 80 data points (70%) were modeled, and 35 data points (30%) were used to evaluate the model. In the form of digital layers, 8 variables potentially affecting the habitat suitability of the plant were selected as independent variables, including; distance from road and river, elevation, plan curvature, precipitation, slope percentage slope aspect and temperature. The results of the relationship between the effective variables and the presence of the plant species showed that the variables of temperature, precipitation, and distance from the road have a greater effect on the presence of the A. podolobus. . The newly derived habitat suitability map produced using the FR model is a powerful tool harnessed for the development of conservation projects of the degraded habitat of A. podolobus. The analytical framework used in this study could be applied to other arid and semi-arid environments to determine suitability habitat of A. podolobus and stabilize this species, also to introduce new adaptive rules for rangeland management.

Keywords

• conservation
• presence of the plant species
• variables
• validation