Abstract: Based on the investigation data of 27 sampling plots,the plant species diversity in the hilly regions of Fangshan Mountain was analyzed from the aspects of component similarity,and species richness in various layers.The results showed that the species richness was lower in tree layer,but higher in shrub and grass layers.The species diversity was decreased with increasing altitude,but was higher on northern than on southern slope at the same altitude.Human activity had a significant effect on the plant species diversity.

Key words: black soil, soil and water conservation plantation, phosphorus fractionations, phosphorus availability.