Synecology of Semi-Steppe Vegetation in Relation to Some Ecological Factors in Polour Rangelands of Mazandaran Province, Iran

This research investigates the vegetation of 4600 ha of Polour semi-steppe rangelands in relation to edaphic and physiographical parameters in Mazandaran province. For this purpose, 23 land units were selected from overlaying slope, aspect and elevation maps using geographic information system (GIS). Within each unit, 3 parallel transects with 100 m length, each containing 10 quadrates (according to vegetation variation) were established. Sampling method was Random systematic. Measured soil properties included texture, organic matter, pH, electrical conductivity, nitrogen, phosphor, and litter. Soil and plant data were analyzed with redundancy analysis and SHAZAM 10 package. RDA analysis suggesting that there is a relatively high correspondence between vegetation and environmental factors that explain 93% of the total variance in data set. RDA results showed that soil slope, aspect, soil texture, acidity, phosphor, and litter were the major environmental factors responsible for variations in vegetation patterns. Furthermore, results also showed that for F. ovina and P. bulbosa, acidity and nitrogen, for A. gossypinus, organic matter and salinity and for D. glomerata, nitrogen have the most important role in plant presence and absence probability.