Abstract: By using the measurement technique of dynamic hydrological process and the estim ation method of landscape ecology, this paper studied the effects of 1986〖KG-*2 〗-〖KG-*7〗2004 land use/cover change (LUCC) on the runoff sediment discharge i n the Luoyugou watershed in Tianshui of Gansu Province in third sub-region of L oess Plateau. The results showed that the LUCC in Luoyugou watershed had signifi cant effects on the annual sediment yield. In 1995〖KG-*2〗-〖KG-*7〗2004, the s ediment discharge was reduced by approximately 630%, compared with that in 198 6〖KG-*2〗-〖KG-*7〗1994, and the reduction effect was more significant with inc reasing annual precipitation. The effects of LUCC on sediment discharge demonstr ated seasonal fluctuation characteristic. Relative to that in 1986〖KG-*2〗-〖KG -*7〗1994, the reduction effect of sediment discharge in 1995〖KG-*2〗-〖KG-*7〗 2004 was more concentrated in the period from May to October, and, the more the monthly precipitation, the more the reduction of monthly average sediment discha rge in 1995〖KG-*2〗-〖KG-*7〗2004 than in 1986〖KG-*2〗-〖KG-*7〗1994. The anal ysis on precipitation and flood peak discharge frequency indicated that under th e same frequency distribution of precipitation intensity, the average sediment c oncentration in any recurrence period in Luoyugou watershed was smaller in 1995 〖KG-*2〗-〖KG-*7〗2004 than in 1986〖KG-*2〗-〖KG-*7〗1994.

Key words: young bearing stage, utilization., Huangguan pear tree, uptake, distribution, ¹⁵N-urea