A survey of some environmental factors affecting on distribution of Agropyron cristatum (Case study: Polur Summer rangelands, mazandaran province)

The aim of this research was to investigate the effects of soil characteristics and topographic factors on distribution of (Agropyron cristatum). Study area which is about 4600 ha is located at Polur Summer Rangelands. After identification of the species sites in this region، data of vegetation، soil and topography were collected. Sampling was conducted in the key area of each site based on randomized-systematic pattern. Within each site was done along three 100 meter transect 10 plots (1m2) established along each transect in 10 meter distances. Three soil samples in each area collected in 0-30 cm and parameters such as N، P، organic material، pH، EC and texture were determined. After collecting data، Plant parameters of Ag. cristatum were analyzed using SPSS software. A matrix of plant stands and environmental factors was prepared and data were analyzed by the Principal Component Analysis (PCA) using PC-ORD software. Results showed that Ag. cristatum species have scattered more along second axis that plant stand were in western aspect and had more density and cover percentage. the most important effective environmental factors in vegetation distribution pattern were elevation، aspect، organic matter، soil texture، N، P and litter.