Effects Of Site Factors On Soil Organic Carbon And Soil Total Nitrogen Contents Of Main Forest Types In The Southern Slope Of The Qinling Mountains

This study was performed to investigate contents and vertical distribution of soil organic carbon and soil total nitrogen in the main forest types in the southern slope of the Qinling Mountains by soil sampling and laboratory analysis.In addition,the relationships between soil organic carbon content,soil total nitrogen content and topographical factors were also studied.And the results were as follows.(1)The contents of soil organic carbon and soil total nitrogen of A soil layer in the main forest types were significantly higher than that B and C soil layers(P<0.05).(2)Soil organic carbon contents of the A,B and C soil layers in Pinus tabulaeformis and Betula albo-sinensi forests increased with the increase of elevation.In comparison,soil organic carbon content of the A,B and C soil layers in Quercus aliena var.acuteserrata forest firstly increased and then decreased with the increase of elevation.Soil total nitrogen contents of the A,B and C soil layers in Quercus aliena var.acuteserrata and Picea asperata forests firstly increased and then decreased with the increase of elevation.Soil total nitrogen contents of the A,B and C soil layers in Pinus tabulaeformis forest decreased with the increase of elevation.(3)Soil organic carbon contents of the A,B and C soil layers in the four forests decreased with the increase of slope position.Soil total nitrogen contents of the A,B and C soil layers in Quercus aliena var.acuteserrata,Pinus tabulaeformis and Betula albo-sinensi forests also decreased with the increase of slope position.(4)Soil organic carbon and total nitrogen contents of the A,B and C soil layers at north-facing slope(including north-facing slope,north-east facing slope and north-west facing slope)in Quercus aliena var.acuteserrata and Pinus tabulaeformis forests were higher that of south-facing slope(including south-facing slope,south-east facing slope and south-west facing slope).Soil total nitrogen contents of the A,B and C soil layers at north-facing slope in Picea asperata forest were higher than that of the other aspects.In comparison,soil organic carbon and total nitrogen contents at south-facing slope in Betula albo-sinensi forest were higher than that of the other aspects.(5)Soil total nitrogen contents in Pinus tabulaeformis,Betula albo-sinensi and Picea asperata forests were increased with the increase of slope.Generally,soil organic carbon contents in Quercus aliena var.acuteserrata and Betula albo-sinensi decreased with increase of slope.In comparison,soil organic carbon content in Picea asperata forest increased with the increase of slope.