Paper

Spatial Variability of Soil organic matter under Different Mixed Beech Forest Type, Iran Hashem Habashi The organic matter content in forest soil depends on the soil conditions, the forest cover (type and composition), topography, hydrological conditions, elevation and management practices. The aim of this contribution was to describe spatial variability of soil organic matter in mixed Hyranican beech (Fagus orientalis Lipsky) forest, Iran by means of geostatistics and to assess the effects of forest types. We selected 172 plots on mixed Hyrcanian beech forests by random grid. Data of forest stand include species name, DBH, crown area, forest type and topographic situation were collected. Soil sampling was conducted by auger sampler in 0-20 Cm depth. Soil organic matter (%) determined by Walkly-Black method, Soil texture determined by Hydrometer method, pH determined by electrical method and SP (%) determined by weighted method. Soil organic matter showed a moderate spatial dependence due to variogram range. Spatial dependency of soil organic matter was decreased by decreasing beech trees GBH in forest types. Anisotropic variogram was used to spherical model and kriged map of spatial variability of Soil organic matter was created. Logistic regression showed soil organic matter was influenced by forest types. These results emphasised the moderate spatial variability of soil organic matter. Spatial correlation indicated that the soil organic matter is strongly affected by forest types. Significant differences in soil organic matter between pure beech forest and mixed beech forest were tested using ANOVA. Correlation analysis indicates that Soil organic matter concentration is in general negatively correlated with sand percent and positively correlated with clay percent and trees crown area.

Keywords: Soil organic matter; Spatial variability; Mixed beech; Iran