The Effect of Canopy Composition on Soil Properties in Pure and Mixed Stands of Beech (Case Study: Aland Forest -Sari)

This paper investigates the influence of closed canopy and canopy gap on soil properties in a pure and mixed beech forest in Alandan forest - Sari. Soil samples were taken from four positions listed in two depths of 0- 10cm and 10-20 cm. Totally 32 soil samples and 16 organic layer samples were taken and transported to the laboratory. Soil texture, pH, EC, bulk density, soil moisture content, organic carbon, total nitrogen, phosphorus and potassium of mineral soil as well as pH, moisture content, nitrogen, phosphorus and potassium of organic layer were measured in laboratory. Results showed that the electrical conductivity of the soil at a depth of 10-20 cm in gaps of pure stand was significantly lower than that of gaps and closed canopy of mixed stand. The gap in pure stand showed significantly lowest percentage of organic carbon. Total N was significantly lower in the gap position comparing with the closed canopy within the pure stand. Difference was significant in the case of Carbon to nitrogen ratio in the second soil depth between gaps and closed canopy in both stands. Soil available K was significantly greater in mixed stand compared to pure one. None of soil properties showed significant differences in depth of 0-10 cm between the various positions in both stands. Relative humidity showed significantly higher percentages in both organic and mineral soil layers in pure compared to mixed stands. The findings suggested that canopy compositions are significantly able to influence some properties of soil n organic and mineral layers.