Effect of vegetation restoration on soil and water erosion and nutrient losses of a severely eroded clayey Plinthudult in southeastern China

The clayey Ultisols in low hilly area in southeastern China were called for agricultural reclamation to meet the increasing food demand. However, little attention was given to soil erosion during land use planning due to lack of information on the amount of soil erosion and how to restore the severely eroded bare soils. The objectives were to estimate the long-term influences of reforestation on soil and water erosion and nutrient losses on a severely eroded bare land derived from Quaternary red clay. The results indicated that reforestation using integrative measures decreased surface runoff and soil erosion on the severely eroded land. On the severely eroded bare land. annual runoff varied from 303 to 1056 mm and annual total soil loss from 53 to 256 tons ha(-1). After reforestation, soil erosion dramatically reduced to 2-43 tons ha(-1) year(-1) from 1988 to 1990 and became negligible since then. The high level of soil erosion was attributed to high rainfall erosivity, readily transportable particles due to the presence of pseudo sand on the bared soil surface formed in the dry season and due to clay dispersion occurring in the long rainy season, and the gully landform. Depositional soil loss accounted for the high proportion of soil loss, while enrichment ratios (ER) of soil nutrients in the suspensional sediment were greater than 1. The results suggest that soil erosion has to be taken into account when planning to convert the clayey soils in the low hilly area for agricultural use, and integrative treasures to reforest are key to prevent soil erosion on the severely eroded bared land. (C) 2003 Elsevier B.V. All rights reserved.