Investigations on orodobility indices and vegetation structure of soils developed from different parentmaterials at Giresun-Yağlıdere watershed

SUMMARY Investigations on Erodobility Indices and Vegetation Structure of Soils Developed from Different Parentmaterials at Giresun- Yağlıdere Watershed This study was conducted in Giresun- Yağlıdere watershed in which, soil erodobility and some physical, chemical and hydrologic soil properties of different parentmaterials, land use types, aspects and attitude levels were studied. For this purpose, soil samples were taken from five different parentmaterials (andesite, basalt, granite, dasite and granodiorite), three different land use types (agriculture land, rangeland and forestland), two different aspect groups (south and north) and two different altitude levels (0-1350 m and 1350-2700 m). A total of 60 soil profiles from 12 different parent material groups were dug and from each soil profile, the samples from two different soil depth level were taken. As indicated below, 17 soil properties such as texture (sand, clay and silt), erodobility indexes (dispersion ratio, colloid/moisture equivalent ratio, erosion ratio and clay ratio), moisture equivalent, permeability, bulk density, soil particle density, porosity, pH, loss on ignition, and available moisture were measured on the soil sample. Soil properties were analyzed statistically using Analysis of Variance, Duncan's Multiple Range Test and Correlation. Differences and relations between the soil properties were examined. Furthermore, maps of the research area were digitized and evaluated with Geographic Information System. The results of laboratory test and statistical analysis can be summarized as follows: 1- According to the variance and correlation analysis, soil properties changed to positive or negative way depending on parent material groups. 2- In terms of dispersion ratio, only the soils developed from basalt were found succestible to ersion. 3- All the watershed soils were found to succeptible erosion according to the colloid/moisture equivalent ratio, erosion ratio and clay ratio. Key Words: Parentrock, Soil Erosion, Land Use Type, Geographic Information System. vm