Predicting the distribution of plant species using logistic regression (Case study: Garizat rangelandsof Yazd province)

The aim of this research was to study the relationships between presence of plant species and environmental factors in garizat rangelands of yazd province and providing their predictive habitat models. after delimitation of the study area, sampling was performed using randomized-systematic method. accordingly, vegetation data including presence and cover percentage were determined in each quadrate. the topographic conditions were recorded in plot locations. soil samples were taken at depths of 0-30 and 30-80 em in each plot. the measured soil variables included texture, lime, saturation moisture, gypsum, acidity (ph), ece and soluble inos (na+, k, mg2+, cr, co3 2-, hco3- and so42-). logistic regression technique was used to analyze the collected data. the results showed that the vegetation distribution is mainly related to soil characteristics such as texture, gravel, ec, gypsum, lime and om. the presence of artemisia sieberi- zygophyllum eurypterum has relation with gravel, lime, available water and ph. ephedra strobilaceae-zygophyllum eurypterum has positive relation with gypsum. rheum ribes-artemisia sieberi has relation with clay and om. cornulaca monacantha has also relation with elevation above sea, gravel and gypsum. the presence of seidlitzia rosmarinus has relation with lime. electrical conductivity is the most factors effect on presence of tamarix ramosissima.