Ecology, Environment and Conservation Paper

CHANGES IN SOIL CHARACTERISTICS OF NATURAL FORESTS UPON REPLACEMENT WITH MONOCULTURE PLANTATIONS IN SRINGERI AREA OF THE WESTERN GHATS, SOUTH INDIA

B.C. Nagaraja and R.K. Somashekar

Abstract

Many studies have reported changes in the soil characteristics of tropical soils following deforestation, whereas similar studies concerning reforestation sites are scarce.This paper reports the impacts of reforestation with fast growing Acacia auriculiformis and other exotic species on soil properties of Western Ghats soils of South India.The results showed significant differences in some of the soil physical and chemical properties in the Wasteland compared to adjacent 8-year old plantation and the surrounding natural forest soils.The particle size indicated that natural forest soils are silty to clayey loam's, whereas the Wastland and Acacia soils are sandy clay to sandy clay loam's, which is suggestive of pulverization by weathering.There occurred a significant decrease in pH, organic, matter, nitrogen, available phosphorus and calcium in Acacia plantation soil, in comparison with the adjacent Wasteland and Natural forest soils. In general natural forest soils containing significantly higher nutrients suffered from nutrients loss under plantation. It is concluded that tropical rain forest soils in Sringeri area of Western Ghats are considerably degraded upon replacement with exotic fast growing species, including Areca orchards to an unrecoverable status through the induced changes in the water balance and disruption in nutrient cycling, dictating the need to prefer native species. Obviously native species must be considered on priority basis in reforestation and afforestation programs.