Study of Species Density in Semi Arid Rangelands by Using Multiple-Linear Regression Analysis

Sarabe narm is a semiarid and cold area in Lorestan province. It is a protected rangelands of Iran in which less modification for its vegetation cover, physical and chemical properties of soil were observed. Initially, the type of vegetation and their sites were determined to evaluate soil from two depths basically for soil texture, organic matter, nitrogen, potassium, phosphorus, lime, pH and electric conductivity. The vegetation cover of the area was categorized into four types: A. Agropyron libanoticum-Acantholimon bromifolium B. Hordeum glaucum–Taeniatherum crinitum C. Astragalus adscendens–Agropyron trichophorum and D. Astragalus adscendens– Daphne mucronata. For data analysis, stepwise multiple-linear regression method was computed which indicated that density of each type was mainly controlled by soil factor especially nitrogen, potassium, soil texture and lime.