Spatial Modeling of The Suitability of Astragalus Podolobus Habitat Using Frequency Ratio

Astragalus podolobus is a thorn less half-shrub plant that is considered as one of the most valuablespecies in the Iran rangelands. It is a kind of nurse plant with an important role in soil and water conservationalong with biodiversity conservation. However, land-use changes and rangelands degradation represent a realthreat to this species. To determine how to manage it better, the potential spatial distribution of this specieswas mapped using a bivariate statistical model (FR: frequency ratio) for the Maraveh Tapeh rangelands ofGolestan province, north-east Iran. A total of ۱۱۵ occurrences of A. podolobus were recorded using GPS duringfield surveys from April to September in ۲۰۱۸ and ۲۰۱۹, then ۸۰ data points (۷۰%) were modeled, and ۳۵ datapoints (۳۰%) were used to evaluate the model. In the form of digital layers, ۸ variables potentially affectingthe habitat suitability of the plant were selected as independent variables, including; distance from road andriver, elevation, plan curvature, precipitation, slope percentage slope aspect and temperature. The results ofthe relationship between the effective variables and the presence of the plant species showed that the variablesof 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 toolharnessed for the development of conservation projects of the degraded habitat of A. podolobus. The analyticalframework used in this study could be applied to other arid and semi-arid environments to determine suitabilityhabitat of A. podolobus and stabilize this species, also to introduce new adaptive rules for rangelandmanagement. Introduction.

Keywords:

Conservation , Presence of the plant species , Variables , Validation