The characteristics

spatial variability and evolution of soil nutrients in artificial forest lands (Caragana korshinskii) with different ages in the loess hilly and gully region are systematically studied through the approach of substituting the temporal serial for the spatial serial. Results show that soil nutrient contents on artificial forest lands are in a low level. Spatial variability of soil available phosphorus(AP) and spatial variability of available potassium(AK) are greater than those of other nutrients in top soils. The environment of factors affects soil nutrients to some extent. Correlation of soil nutrients with elevation

gradient and aspect is negative

while correlation of soil nutrients with position of slope and relief is positive. The soil nutrient contents increase with the increase in landuse year. Significant correlation is found between soil nutrient contents and landuse year. No significant increases in organic matter(OM)

total nitrogen(TN)

available nitrogen(AN) and available phosphorus(AP) are found with the increase in landuse year. Total phosphorus(TP)keeps a relatively stable content in different landuse years. However

AK increases significantly after the community of many years. From the formula of soil nutrient index(SNI)

we can know that OM

TN

AN can reach the middle nutrient level after 35 years

and AK can reach the middle nutrient level after 27 years on artificial forest land in the loess hilly and gully region.