Effects of natural and artificial vegetation types onsoil properties in Loess Hilly region

The effects on improving soil quality between different vegetation types on the Loess Plateau are quite different. Studies on the effects of natural and artificial vegetation type on soil characteristics are help to understand the relationships of vegetation restoration and soil quality, and also beneficial to accurate assessment of environmental benefits of different vegetation restoration models on the Loess Plateau. In this study, the Yangou watershed located in the center Loess Hilly region was taken as a case. By comparing the soil physical and chemical properties of 11 typical vegetation types, the effects on soil properties between natural and artificial vegetation types were analyzed. The results showed that the natural and artificial vegetation types have significantly different effects on the soil properties. The order of soil water content in 200 cm layer in different vegetation types was farmland>natural grassland>artificial woodland> orchard>artificial shrub land>natural shrub land. Compared with farmland, soil bulk density of natural shrub land and natural grassland reduced the most obviously, while soil bulk density of artificial woodland, artificial shrub land and orchard had fewer differences in decline. Soil organic matter and total nitrogen had markedly improved in natural shrub land, natural grass and artificial shrub land, while they didn't improve much in artificial woodlands and orchard. Soil organic matter and total nitrogen of different vegetation declined with soil depth. The vertical changes in soil organic matter and total nitrogen of farmland, orchard and artificial woodland were less, while that of natural shrub land, natural grassland and artificial shrub land changed greatly. Soil total phosphorus changed little among different vegetation types and in soil profile. Overall, the natural vegetation types were better than artificial vegetation types in improving soil properties, and the artificial shrubs were better than artificial forest in improving soil properties in Loess Hilly region.