Study of habitat suitability for Dorema ammoniacum establishment in Sabz Dasht rangelands of Bafgh, Yazd province

The aim of this study was to evaluate the efficiency of logistic regression method in determining of the environmental factors effecting on the presence of Dorema ammoniacum D. DON, and to identify the habitat conditions of this species. Vegetation sampling was conducted random-systematically with establishment of plots along 9 transects in the presence region and 9 transects in the absence region. The size of plots was determined according to the type of existing species and using minimum area method and the number of plots (10 plots along each transect) was determined using statistical method. Data related to the presence and absence of the selected species (180 plot samples of each) was collected and environmental factors of the sampling sites including: topography, climate and soil were investigated. For soil sampling, profiles were drilled at the beginning, middle and end of each transect from two depths of 0-30 and 30-60 cm, then samples of each depth were mixed together and prepared as a composite sample, and the physical and chemical properties of the soil were measured at the laboratory according to the usual methods. Habitat prediction modeling was performed using logistic regression method and D. ammoniacum habitat predicted map was derived using the prediction model. According to the prediction model, slope of habitat, lime and clay of the second soil depth have the highest effect on the species distribution. After determining the threshold of optimal presence, the accuracy of the predicted map with the actual map was measured using the kappa coefficient. According to the optimal presence threshold (0.5), and the amount of kappa coefficient (0.5), the result of model evaluation was concluded as a good agreement. Results show that the logistic regression method is able to predict the habitat of D. ammoniacum, thus the distribution of this important and valuable species, and derived information from this study can be used in the locating of the areas prone to restoration of this species at the study area and the areas with the same ecological conditions.