ECOLOGICAL EFFICIENCY OF THE SEMI-DECIDUOUS MONSOONFOREST AT JIANFENGLING, HAINAN ISLAND Ⅳ.SOIL FERTILITY ANALYSIS ON SHIFTING CULTIVATION

Four aspects of soil deterioration in the tropical forest had been demonstrated according to experiment of the shifting cultivation on ecological efficiency of the semi-deciduous monsoonforest at Jianfengling,Hainan Island.With losing of the litterfall the supplemental source of the soil fertility and the hydrologic function are declined; soil and water erosion severe; the ability of water transportation and the storage capacity are decreased; soil fertility degraded owing to deterioration of the soil physico-chemical properties.It is suggested that the shifting cultivation system must be rid of practice establishing an agro-forest system based mainly on the woody plants,drawing up resonable overall and management for the tropical forest,preventing from slash-and-burn cultivation,carrying out of planting technique of ecology,so as to maintain the soil fertility and the protection of soil resource of the tropical forest.