Effects of environmental factors on the establishment and distribution of plant habitats in the southern part of Alborz

Knowledge on the effects of environmental factors affecting the distribution of plant communities provides information about ecological characteristics of species as well as the conditions of vegetation habitat. The current study was performed in Halejerd, west of Tehran to investigate the effects of environmental factors on the distribution of plant sites. This research was aimed to identify the most effective factors on the establishment of plant sites. After identifying the region, vegetation types were selected and sampling was done by random-systematic method. Minimal area method was used to determine the plot size. Five vegetation types were identified. Three soil profiles were dug in each vegetation type and two soil samples were taken from two soil depths. Soil characteristics including soil texture, pH, electrical conductivity, potassium, nitrogen, phosphorus, organic matter, organic carbon and TNV were measured. Result showed that the studied plant sites differed in terms of soil characteristics and the factors of each component were characterized. According to the obtained graph and considering variable coefficients, the content of silt and potassium increased in the first component while in the second component the content of sand and nitrogen increased. Also, soil chemical and physical characteristics are involved in the separation of vegetation types. Important and effective physical and chemical characteristics were sand, silt, potassium and nitrogen, respectively. In order to analyze the environmental factors (soil characteristics) associated with the distribution of plant sites principal component analysis (PCA) was used. Results showed that there was a special relationship between the distribution of different vegetation types and soil characteristics. Also it was found that edaphic factors including soil texture, potassium and nitrogen were more effective in species distribution.