Study of Physical and Chemical Soil Properties Variations Using Principal Component Analysis Method in the Forest, North of Iran

The field study was conducted in one district of Educational-Experimental forest at Tehran University (Kheirood-Kenar forest) in the North of Iran. Eighty-five soil profiles were dug in the site of study and several chemical and physical soil properties were considered. These factors included: soil pH, soil texture, bulk density, organic carbon, total nitrogen, extractable phosphorus and depth of soil. Principal Component Analysis (PCA), was used to identify the variations of soil properties. Results showed that there are significant relationships between some soil factors and two PCA axes. Content of clay in A1 and A2 horizons, bulk density, organic carbon and total nitrogen in A1 horizon, and content of silt in A2 horizon, correlated to the first PCA axis. Content of clay, pH, carbon percentage and silt content of B1 Horizon, and soil depth, were the most important factors correlated to the second PCA axis. Soil profiles that consist high content of clay, with heavy soil texture, and soil profiles with high content of silt, occupied different areas in the forest. The content of total nitrogen and organic carbon also varied noticeably amongst the soil profiles. The variations of soil properties showed correlation with the distribution of trees and variations of altitude.