Study On Rhizosphere Soil Properties And Mycorrhizal Infection Rate Of Pinus Tabulaefolius Forest At Different Elevation Gradient In Huoditang,qinling Mountains

The elevation gradient can affect the soil physichemical properties,soil enzyme activities and the colonization rate of mycorrhizal fungi by changing the surface vegetation,soil and climate factors.In this study,three Pinus tabulaeformis forests under different elevation gradients(1500,1900 and 2300 m)in Huoditang forest area of Qinling Mountains,China,were selected as the study places.After collection of the rhizosphericsoil samples and roots of P.tabulaeformis,the rhizospheric soil physichemical properties,enzyme activities and the root colonization rate of P.tabulaeformis by ectomycorrhizal fungi(ECMF)and dark septate endophytes(DSE)were studied to analyze the variation of soil propertiesalong with elevation gradient,as well as the responses of soil enzyme activities and mycorrhizal fungal colonization rates to the soil physichemical properties under different elevation gradients.The main results were listed as follows:1.In Huoditang forest area of Qinling Mountains,the rhizospheric soil physichemical properties of P.tabulaeformis forests such as total K,total P,nitrate N,ammonia N,C/N,soil moisture content,ground temperature and pH,were significantly different at different altitudes.With the increase of altitude,the change trends of different soil physichemical properties were different,showing as a decrease in soil temperature and pH value,but a increase in soil moisture content,available K,available P,nitrate and ammonium nitrogen.In addition,the contents of total K,organic carbon and C/N were higher in the middle elevation(1900 m)forest,but the lowest in the middle altitude forest.2.The rhizospheric soil enzyme activities of P.tabulaeformis forests at different altitude were also significant different.At middle altitude,sucrase activity was higher,but urease activity was lower.Phosphatase activity increased with the increase of altitude,while dehydrogenase activity decreased.There was no significant difference in catalase activities among different altitude gradients.In addition,soil enzyme activities at different altitudes were strongly correlated with the soil physichemical properties.3.At the highest altitude,the mycelial density in rhizospheric soil ofP.tabulaeformis forests was the lowest,and the root colonization rates of ECMF and DSE were significantly affected.The roots colonization rate of ECMF was the highest in P.tabulaeformisforest at the lowest altitude,but lower at middle altitude.There was no significant difference between the colonization rates of DSE at the highest and lowest altitudes,but the colonization rate reached the maximum at 1900 m above sea level.In addition,the change of altitude gradient had no significant effect on the total infection rate of mycorrhizal fungi and the number of DSE microsclerotia.The results of correlation analysis showed that there was no significant correlation between the colonization rate of mycorrhizal fungi in roots of P.tabulaeformis and soil physichemical properties,as well as the soil enzyme activities.