Investigating the role of topographic factors on spatial distribution of plant species using logistic regression (Case study: Baghe-Shadi forest, Harat, Yazd)

To investigate relation of slope, aspect and elevation in predicting spatial distribution of tree and shrub species in arid forests of south Yazd, 125 sampling plots were selected in randomized block pattern in five sub-district of study area. In addition to topographic factors, presence of plant species and their frequency were measured and recorded. Logistic regression was conducted and in the case of significance, suitable model was provided. Distribution map of species was drawn according to probabilities derived from logistic regression analysis. To determine accuracy of maps we used 20 percent of primary data. According to these data the rate of accuracy was in range of 90-75 percent. Finally relations between topographic factors and presence of species were interpreted. Results found that elevation is the most important factor for predicting spatial distribution of plant species in study area and predicts from 16 to 46 percents of variations in presence. But slope and aspect were not suitable to be included in the models. According to thresholds determined in the results it can be said that Acer cinerascens and Amygdalus eleagnifolia can be regarded for planting in higher elevations but Amygdalus lycioides is suitable for planting in lower elevations.