Study of Soil Diversity and Evolution in Different Elevation Surfaces of Western Hillsides of Talesh Mountain

Spatial variability of the soil properties is related to the environmental factors such as climate, topography, parent material and vegetation. Topography causes significant differences in soil properties through the three factors of elevation, natural drainage and slope. This research was carried out to investigate the effect of elevation on some physical and chemical characteristics, type and content of the clay minerals, and finally on the evolution of soils of an elevation profile in Talesh Mountain in Ardabil province. Following excavation and description of five profiles on non-eroded surfaces, physical, chemical and clay mineralogy experiments were performed on the samples. The results showed that weathering intensity and type of pedological processes were different and hada significant effect on some soil characteristics such as clay content, different forms of iron, minerals and soil classification at the different surfaces of elevation. With decreasing the altitude, the amount of illite minerals was reduced but the amount of smectite minerals has increased, which is a reason for the improved weathering and evolution of the soils. The results show that toeslope lands have evolved soils of Vertisols and Mollisols, but highlands have Inceptisols with low degree of evolution. Addition, in the studied elevation profile, as the altitude decreases, the climate becomes warmer and consequently the intensity of pedogenic processes increases.The increase in the amount of crystalline iron (Fed-Feo), as an indicator of soil evolution, from 2303.9 mg kg-1 at the topslope to 7558 mg kg-1 at the toeslope of the mountain illustrates this evolutionary trend.