Distribution of vegetation type according to edaphic properties and topography in Iran

The current research was carried out to find the most effective environmental factors in plant species distribution. For this purpose, a study was conducted in the Taleghan rangelands of Tehran province. Based on a vegetation map and field surveys, indicator vegetation types were identified. Within each type, 3 parallel transects with 150 m length, each containing 15 quadrates (according to vegetation variations) were established. The sampling method was randomized systematic. Quadrat size was determined for each vegetation type using the minimal area method. The floristic list and canopy cover percentage were determined in each quadrat. The topographic conditions (elevation from sea, aspect, and slope) were recorded in quadrat locations. Soil samples were taken from 0-30 cm in starting and ending points of each transect. Measured soil properties included depth, texture, organic matter, lime, pH, electrical conductivity, nitrogen, and potassium. To determine the most environmentally effective factors on plant distribution, multivariate techniques, including the principal component analysis (PCA) and canonical correspondence analysis (CCA) methods were applied. The results indicated that edaphically factors such as texture, potassium, and organic matter play a main role in the distribution of plant species.