Distribution characteristics of soil nutrient and pH in rhizosphere versus non-rhizosphere from dominant shrub along different slope position in a karst region

To test the effects of plant type and slope position on the distribution characteristics of nutrients and pH in plant rhizosphere and non-rhizosphere soil,two dominant shrubs (Syzygium championii and Pyracantha fortuneana) were selected in a karst region of Guangxi,Southwest China.Rhizosphere soil showed nutrients enrichment.An enrichment of soil organic carbon and available phosphorus was more pronounced in pyracanthafortuneana rhizosphere,and an enrichment of soil organic carbon and total nitrogen was also found in syzygium championii rhizosphere.Significant difference in soil nutrients among slope positions was found in shrub rhizosphere and non-rhizosphere (p<0.05).In rhizosphere soil,soil organic carbon content had significantly positive correlation with total nitrogen content and significantly negative correlation with available phosphorus content (p<0.05).In non-rhizosphere soil,soil organic carbon content had significantly positive correlations with the content of total nitrogen and available phosphorus (p<0.05).A two-factor variance analysis showed that slope position had greater effect on physico-chemical properties than plant type.The above results suggested that the dominant plants in karst shrub are beneficial to improve the utilization of soil nutrients.In addition,slope position should be considered,when shrub species were used to improve soil quality in karst regions.