The major goal of this study is to develop reasonable operation and management practices of Robinia pswudoacacia plantation and improve its stability.Different interfering measures

including Robinia with Caragana

Robinia with pine and Robinia with Forsythia

and Robiniapure forest were investigated through field survey and labortory analysis to analysis and compare the physical and chemical properties

the growth status

and understory species diversity of artificial pure and mixed Robinia.The result showed that different management methods have low influence on population density for the both mixed and pure Robinia;the density of Robinaremained 1 000~1 500plant/hm2 through self-propagation and repair.However

the volume of the pure forest was significant higher than the mixed forests.The stem diameter of pure forest ranged from 8cm to 16cm

accounting for 79.31%of Robiniain sample plot

while stem diameter of the mixed varied from 2cm to 12cm for 82.58%of the Robinia.The coefficient of correlation between diameter and the projection area of Robinia was 0.385in pure forest

and 0.735in the mixed forests.The structure and tree shape of mixed forests was better than that of the pure forest.The pure forest showed less effectiveness inimproving soil bulk density and organic matter than the mixed forests;specifically

the Robinia and Caragana mixed forest exhibited the highest effectiveness.Soil organic matter contents of the pure and mixed forests in 0to 5cm soil layer were 15.50g/kg and 15.19g/kg

respectively.The average organic matter in 5cm to 60 cm soil layer under the mixed forest was 70.6% higher than that under the pure forest.Diversity index of understory herb layer in pure forest was higher than the mixed

however

the richness and evenness index were lower