The satellite remote sensing technology, the method of the surface runoff collection of
erosion plot and the evaluation method
of agricultural eco economy are used to investigate the soil erosion, the situation of land use, the
storage volume of soil and water conservation woods, the coverage of
forest and grass, the increasing output of grain, the storage volume of closure preserved forest and young growth in restored Longchuan small watershed, Muding county, Yunnan province, which has been harnessed for 8 years. It indicates that after five year harness and preservation, the soil erosion amount decreases from 594.00
t of 1989 to 177.00 t of 1997, as occupies 29.7% of the 1989s erosion amount. Among the types of land use, the square of dry land decreases 499.40 hm\+2; the one of terrace increases 517 hm\+2; the square of man made woods increases 9 484 hm\+2. The storage amount of soil and water conservation woods is 223 460 m\+3 per year and that of closure preserved forest and young growth is 53 171 m\+3. The coverage of forest and grass goes up to 74.6% of 1997 from 38.95% of 1989; the total amount of grain is 2.89×10 7 kg, increased by 34.3%; the amount of agricultural product is 4 935 kg/hm\+2; the pure income of a farmer is 511 yuan.