アフリカニジェールにおける過度土地利用による土壌養分減少とシロアリ塚による養分保持

概要

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According to the UNCCD, over 250 million people are directly affected by desertification, and a third of the earth's land surface is at risk. Though desertification is a world-wide problem, tropical and semi-tropical regions, especially Africa, are affected most. The tropical soils are generally less fertile and the decomposition rate of soil organic matter is more rapid than that of temperate soils. Therefore nutrient loss from soils due to intensive land use is a serious problem in tropical regions, and leads to a loss of crop productivity and water pollution. To prevent nutrient loss from tropical soils, we evaluated termite mounds as reservoirs of soil nutrients in natural ecosystems. The carbon and nitrogen contents of termite mounds and surrounding soils were investigated in areas of different land use such as forest, bush, pasture, cropland and bare land in Niger, West Africa. The results indicated that intensive land use decreases soil carbon and nitrogen dramatically and that termite mounds immobilize a certain amount of soil carbon (0-1.3%) and nitrogen (0-0.15 %). These findings suggest that termite mounds retain soil nutrients from a long-term viewpoint, and that this function of termite mounds must be important in areas of infertile tropical soil. The evaluation of termite mounds as soil nutrient reservoirs may be a new field for studies of soil conservation and desertification.
日本生態学会の論文
2004-08-25