Relationship between some rangeland species distribution and environmental factors in Chahar-Bagh region of Golestan province

The present study examines the relationship between vegetation and soil characteristics in addition to topographic factors to determine the most effective factors on the formation and establishment of vegetation in rangeland of Chaharbagh. After identifying the study area and determining the vegetation types, in each type along four 100 m transects, ten 2×2 m plots were put based on randomsystematic method. The size of sampling plots and their number was determined according to minimal area and statistical methods. Along each transect, two soil samples were taken from 0-20 cm and more than 20 cm depths. In addition, elevation, aspect and slope were recorded, too. Soil samples were transported to soil laboratory and properties of texture, acidity, electrical conductivity, potassium, nitrogen, phosphorus, organic matter and lime were measured. After data collection, TWINSPAN was applied to classify the vegetation. Four ecological groups (the same four vegetative types) were obtained. In order to analyze the relationship of soil and topographic properties with vegetation changes, PCA and CCA methods were used. The results of both methods were almost the same. Results showed that the occurrence and distribution of understudy vegetation is hugely affected by some soil factors including texture, nitrogen, potassium, organic matter and lime compared to other properties of soil and topographic factors.