Distribution Characteristics Of Soil Organic Carbon Density And Available Soil Nutrients Of Main Forest Types In The Southern Slope Of The Qinling Mountains

The present study was performed to investigate contents and distribution characteristics of soil organic carbon density?SOCD?and soil nutrient in the main forest types in the southern slope of the Qinling Mountains by soil sampling and laboratory analysis.In addition,the relationships between SOCD,soil nutrients and environmental factors were also investigated.And the main results showed as follows.?1?The variable coefficient of SOCD in the main forest types was 0.49,and indicted that there were large spatial variation of SOCD in our study region.SOCD of the A,B and C soil layers were 5.13 kg.m^-2?3.53 kg.m^-22 and 2.21 kg.m^-2,and accounted for 47.2%?32.5%and 20.3%of the total SOCD,respectively.This suggested that there were large spatial variation of SOCD at different soil layers.?2?The average value of available N in the main forest types was124.8 mg.kg^-1,and suggested that there were higher soil available N in this region.There were relatively low spatial variation of soil available N.In comparison,the spatial variation of soil available P was large.The soil available N,available P and available K were mainly distributed in the soil layer A.?3?SOCD was increased with the increasing of elevation.SOCD in the four forest types were positively correlated with soil available N and capacity of exchangeable base?P<0.05,P<0.01?.?4?Soil available nutrient contents were increased with the increasing of elevation.The soil in broad-leaved tree species has higher soil available nutrient contents than that of coniferous species at the same elevation interval.?5?Soil available N contents in the two forest types?Quercus aliena var.acuteserrata and Pinus tabulaeformis?at the lower elevation were positively correlated with SOCD and capacity of exchangeable base?P<0.05,P<0.01?.In comparison,soil available N contents in the two forest types?Betula albo-sinensi and Picea asperata?at the higher elevation were positively correlated with SOCD and soil pH?P<0.05,P<0.01?.Soil available K in the two broad-leaved tree species?Quercus aliena var.acuteserrata and Betula albo-sinensi?were positively correlated with elevation and soil available P?P<0.05,P<0.01?.Soil available K in the two coniferous tree species?Pinus tabulaeformis and Picea asperata?were positively correlated with soil available P and pH?P<0.05,P<0.01?.