This study was carried out to investigate the relationships between soil, topography and geology factors
and range plant types on Ghazvin - Kohin region. On the basis of fieldwork, four vegetation types were
identified and their relationships with topography, soil characteristics and geology factors were investigated.
Samples were taken based on random systematic procedure. The number of samples were calculated
using statistical technique while the area of plot varied between 1.5 to 2 times of the biggest available plant
species in terms of canopy cover. For each plant type, five soil profiles were duged .The soil samples were
taken form different layers of soil and the soil parameters were determined including: texture, EC, pH, N,
K, P, OM, SAR and Lime. To do this, the USDA standard method was used. Topography factors such as
elevation, aspect, slope as well as geology were considered. A multivariate analysis was carried out to
determine the rate of relationship between vegetation types and studied factors. A matrix of vegetation
types and factors were then prepared. The ordination of vegetation and studied factors was done by the
Principal Component Analysis (PCA) using PC-ORD software. The results showed that the environmental
factors affect both the vegetation establishment and flora distribution. Among others the most important
factors are geology, lime, texture, OM and K.