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.