Effect of Position and Slope Aspect on Organic Carbon, Total Nitrogen and Available Phosphorus in Forest Soils (Case Study: The Forest of Ilam Province, Dalab)

摘要

Soil is one of the most important components in forests and distinguishing soil types and soil capability are first steps in forest management. The main aim of this study was to determine relationship between slope aspect and position, and chemical properties of the soil. Soil sampling was done in Tang-e-Dalab in Ilam province which is a part of southern Zagros. Samples were collected in both northern and southern slopes of oak stand (Quercus brantii). In each slope, three transects 50m apart were sampled. Overall number of samples was 60. After data normalization, the means were compared by Duncan test. Slope aspects influenced organic carbon and total nitrogen of soil. These parameters were higher in northern slope than southern one. Slope position showed a significant effect on C, N and P. Also, concentration of C, N and P were increased by moving down the position. Most amounts of C, N and P were 5.84%, 0.58% and 108.19 mg/kg in bottom, middle and bottom of northern aspect, respectively. The least amounts of C, N and P were 3.31%, 0.24% and 37.83 mg/kg in bottom, middle of southern aspect and top of northern aspect, respectively. The results of this study confirmed that nutrient concentration in northern slope was more than southern slope and nutrient concentration in soil was increased by moving downward.