Base on testing results of top-soils and deep-soils

distribution characteristics of organic carbon(abbrev org.C) in soils were discussed by types of soils

elevations

degrees of slope

and vegetation covering.It can be concluded that soils in the Three Gorge Reservoir District belong to mineral soils

because of lower soil org.C.Under the same natural condition of pedogenesis

Parent rocks play an important role in distribution of org.C in soils.In the limestone area the soils are abundant in org.C.on the other hand

in the sandstone and mudstone districts the contents of org.C in the soils are lower.In terms of the degree of slope

the contents of org.C in the purple soils increase with the decline of the degree of slope.When the elevation decreases

the contents of org.C in the purple soils decline

too.When the parents rocks

climate and topography are similar

the contents of org.C in purple soils are determined partially by the type of vegetational cover.Soils in the tussock and broadleaf hurst areas contain more org.C relatively

than soils in the mixing forest

shrubbery and conifer forest areas.