On the base of field suvey in standard plots

the overall diversity

plant community diversity and species diversity index were analyzed for Robinia p seudoacacia L.plantations in Chunhua County of Shaanxi Province on the Loess Plateau.The relationship between path rank

average tree height and density were also explored.Results show that after several years of natural recovery in Robinia p seudoacacia L.plantations

12 shrub species belonging to 10 genera of 7 families

and 46 species in 37 genera of 17 families in herbaceous layers were found.The plant species richness and the diversity index increased significantly.The stratification between shrub and herbaceous layers under trees was more obvious.In contrast

the plant diversity and the important values in the herbaceous layer were higher than those of the shrub layer.Understory plants grew significantly better on the sunny and downhill slopes with angles less than 35 degree and medium density of 1 000~ 1 500 tree/ hm2.The tree diameters decreased accordingly with the increase of forest density.When density was less than 1 500 tree/ hm2

the average height was significantly increased with the average density.