Effects Of Thinning On Soil Active Organic Carbon And Enzyme Activities In Betula Albosinensis Forest On The Southern Slope Of Qinling Mountain

In this study,we selected the Betula albosinensis forest on the southern slope of the Qinling Mountains as a research object,and set up five research plots with cultivating thinning intensity(5%,10%,15%,20%,and 25%),and uncutted Control plot(CK).By studying the differences in SOC,active organic carbon content,enzyme activity and dynamic changes under different thinning intensity.We can provide reference for the scientific tending management of Betula albosinensis forest on the southern slope of Qinling Mountain.The main results are as follows:1.The thinning intensity has a significant effect on the SOC content.Compared with CK,10%,15% and 20% of the thinning intensity can significantly increase the SOC content(P<0.05),and 25% of the thinning intensity can significantly reduce the SOC content.The order of soil organic carbon content under different thinning intensity is15%>10%>20%>CK>5%>25%.2.The thinning intensity can increase the ROC content.When the thinning intensity is15%,the ROC content is most obvious.With the increase of the thinning intensity,the ROC content first increases and then decreases.The order of ROC content under each cutting intensity is 15%>10%>20%>25%>CK>5%;ROC accounts for 17.61%-23.31% of organic carbon,only when the thinning intensity is 15%.ROC accounted for a significant decrease in the proportion of organic carbon(P<0.05).3.Different thinning intensity can reduce the content of LFOC.As the intensity of the thinning increases,the content of LFOC decreases more obviously.The LFOC content under each cutting intensity is CK>5%>10%>15%>20%>25%;the ratio of LFOC to organic carbon is between 16.17%-28.37%.Each cutting intensity can reduce the ratio of LFOC to total organic carbon,and the reduction is most obvious when the thinning intensity is 15%,20% and 5%.4.Each cutting intensity can increase the DOC content.As the intensity of the thinning increases,the DOC content first increases and then decreases.When the thinning intensity exceeded 10%,the increase of DOC content was not significant(P<0.05).The order of DOC content under each cutting intensity is 20%>15%>25%>10%>5%>CK.DOC accounts for between 0.57% and 0.82% of organic carbon,and 10% and 15% of the thinning intensity can significantly reduce the DOC ratio.5.SOC and active organic carbon have obvious temporal dynamics.The dynamic changes of SOC and ROC were the highest in October and the lowest in July.The LFOC content was the highest in July and the lowest in January.The DOC content was the highest in January and the lowest in July.The 20% and 25% of the thinning intensity have a great influence on the dynamic changes of SOC and active organic carbon.6.The thinning intensity can significantly increase soil catalase and alkaline phosphatase activity,significantly reduce soil urease activity,and has no significant effect on soil polyphenol oxidase activity.And when the thinning intensity is 15%,the four soil enzyme activities are the largest;7.There were significant temporal dynamic changes in the four soil enzyme activities.Different enzymes showed significant differences with time.Polyphenol oxidase and alkaline phosphatase had the highest activity in July;catalase had the highest activity in April;urease had higher activity in July and October.The thinning intensity of 25% has a great influence on the dynamic changes of soil enzyme activity.