Land use evaluation using the universal soil loss equation in a small drainage basin in Sichuan Province, China

概要

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Soil loss from forest and cropland is one of the most severe ecological problems facing the world. Soil loss is irreversible, so it directly affects agricultural production and ecosystems. We need to determine the quantity of soil loss and develop a conservation plan. This study evaluates land use and soil loss in China by using the Universal Soil Loss Equation (USLE). The study area (34.7 ha) is a small drainage basin in Sichuan Province in China. Here, massive deforestation was carried out for getting fuelwood around 1958, and reforestation was carried out from 1966 to 1976. We calculated the annual soil loss from this site for 1965 (before reforestation) and 1995 (after reforestation) as 5.9 ×103 t (169.2 t/ha) and 1.8 × 103 t (50.9 t/ha), respectively. These values reveal that reforestation is very effective in soil loss reduction. Soil loss from July to September was accounted for 82% of the annual loss. Attention should be paid to land use and management during these months. The current total soil loss exceeds the annual soil loss allowances in Japan (11.0-16.5 t/ha). It has been shown that it is possible to reduce the soil loss below 16.8 t/ha by increasing the forest area by 5% in the catchment and shifting the forests to the sloping terrain and on highly erodible soils with high KLS values.
日本緑化工学会の論文