Revista Sociedade & Natureza (May 2005)
VARIATIONS IN SOIL PROPERTIES AS AFFECTED BY DEFORESTATION ON LOESS-DERIVED HILLSLOPES OF GOLESTAN PROVINCE, NORTHERN IRAN
Abstract
Deforestation and shift of land use to agriculture, is of great concern in Golestan Province andhas brought hazardous problems of flooding, landslide and soil loss. Soil organic carbon, totalnitrogen content, available phosphorous and potassium, calcium carbonate content, thicknessof A horizons and some important soil properties were studied on forested soils and comparedwith the adjacent deforested and cultivated soils. The studied soils were formed on a hillslopewith parent material consisted mainly of loess deposits. Forested and deforested soils wereclassified as Calcic Hapludolls and Typic Hapludolls, respectively. The studied soils were allcalcareous with the pH value of 7-7.9. The soil texture was silty clay loam with the siltcontent of 54-60%. The results revealed that the soil organic carbon, total nitrogen contentand available potassium, were significantly lower in the deforestated soils. The thickness ofmollic horizons was also reduced after deforestation in all studied pedons. While calciumcarbonate contents of the subsurface horizon of the forested soils are significantly highercompared to the surface horizon due to the leaching processes, it is considerably high in thesurface horizons of the deforested soils and does not change significantly with depth. Thispoints to the effect of deforestation and cultivation practices which has led to soil erosion andthe subsequent exposure of the highly calcareous subsurface horizon. Available soilphosphorous did not show any significant change by deforestation.
