The objectives of this research were to identify the ecological species groups and study the relationship between topographic and edaphic factors with plant species to determine the main factors affecting the separation of vegetation types in Khanikan lowland forests of Mazandaran province - North of Iran. Vegetation was sampled with randomized - systematic method. Vegetation data including density and cover percentage were estimated quantitatively within each quadrate, and using the two - way indicator species analysis (TWINSPAN). Vegetation was classified into different groups. The topographic conditions were recorded in quadrate locations. Soil samples were taken from organic horizon (litter layer), and mineral layers (0-10, 10-20, and 20-30 cm). Soil acidity, bulk density, saturation moisture, electrical conductivity, organic carbon, total nitrogen, cation exchangeable capacity, available phosphorous, soil texture, lime, biomass of earthworms, litter carbon, and litter nitrogen were measured. Multivariate techniques were used to analyze the collected data. The results indicated that the vegetation distribution pattern was mainly related to soil characteristics such as pH, bulk density, texture, phosphorous, organic carbon, nitrogen and CEC. Totally, considering the habitat conditions and ecological needs, each plant species has a significant relation with soil properties.
