Variability And Influencing Factors Of Soil Organic Carbon Stability Of Coniferous Forest In Taiyue Mountain,Shanxi Province

The content and stability of soil organic carbon in forest ecosystem are affected by forest age,forest type,forest renewal modes and other factors.In this study,the stability of soil organic carbon and its influencing factors of coniferous forest in Taiyue Mountain,Shanxi Province were studied.The response law of soil organic carbon and its stability to different forest types were discussed to improve the understanding of soil nutrients in Taiyue Mountain in Shanxi Province,and provide scientific basis and reasonable suggestions for actual management and production.The main conclusions of this study are as follows:(1)Soil organic carbon content,soil moisture content,soil nutrient content,soil enzyme activity and standing stock of surface litter in 40,80 and 110-year-old Pinus tabuliformis forest increased with the increase of forest age,which led to the continuous improvement of soil physical and chemical properties.Soil carbon pool management index showed an overall increasing trend.The fractal dimension of soil particles showed a decreasing trend,indicating that the soil texture in this area tended to become thicker with the increase of forest age.Stable organic carbon played a leading role in organic carbon components.After maturation of Pinus tabuliformis forest,more organic carbon was stored in the soil in a stable form,and the stability of soil organic carbon pool was gradually enhanced.(2)There were many differences in soil physical and chemical properties of Pinus tabuliformis forest under different forest renewal modes.Proper thinning after artificial regeneration could increase soil moisture content,organic matter content,total nitrogen content,cation exchange capacity,complex iron and aluminum oxide content and fine root biomass,while reduced the fractal dimension of soil particles.Compared with artificial renewal,natural renewal could significantly improve soil organic carbon stability coefficient and reduce carbon pool management index,indicating that natural regeneration can reduce soil carbon pool activity and soil organic carbon quality in Pinus tabuliformis forest.(3)In the pure forest of Pinus tabuliformis,Larix gmelinii var.principis-rupprechtii and mixed forest of Pinus tabuliformis and Larix gmelinii var.principis-rupprechtii of the same forest age in Taiyue Mountain,the surface soil moisture content,organic carbon content,soil nutrient content,?-1,4-glucosidase and cellulose disaccharidase activity and soil carbon pool management index increased in turn.The organic carbon stability coefficient decreased,indicating that the mixed forest increased the activity of soil carbon pool and the content of soil nutrients.The soil organic carbon pool of the three forest types was dominated by low oxidizing organic carbon.(4)Soil organic carbon stability was closely related to soil texture,nutrient content,soil enzyme activity,surface litter and plant roots.The clay content of soil physical properties had the largest contribution rate to the stability of organic carbon,reaching 32.24%,and had a strong negative correlation with its stability.The organic matter and complex iron oxide content of soil chemical properties had a higher contribution rate to the stability of organic carbon,which were 42.78% and25.48%,respectively.The organic matter content had a positive correlation with it,and the complex iron oxide content had a positive correlation with it.Among the characteristic indexes of soil enzyme,litter and root biomass,the activities of ?-1,4-glucosidase and cellulose hydrolase contributed 24.04%and 23.95% to the changes,respectively,and they had a strong positive correlation with their stability.(5)In the process of forest management,different forest ages,renewal methods and forest types have different effects on the stability of forest soil organic carbon and carbon pool management index.From the point of view of forest age,the soil organic carbon stability of 40 year old Pinus tabuliformis forest is low and the carbon storage management index is high.This forest age could be used as the reference standard for the management of the forest age of Pinus tabuliformis in this area.From the point of view of renewal mode,the artificial regeneration management of clear-cutting Pinus tabuliformis forest was carried out first,and then a certain degress(40%)of thinning in the later management was beneficial to carbon pool regeneration and stand development.From the point of view of forest types,the selection of suitable tree species for stand mixed allocation was beneficial to reduce the stability of soil organic carbon and promote the growth and development of trees.