Study On The Change Regularity Of Soil Organic Carbon In Different Stand Types And Its Relationship With Microorganism And Enzyme Activity

Soil organic carbon pool is an important part of carbon cycle,which affects the global atmospheric carbon dioxide concentration.Soil microorganisms and enzymes are important active components in the decomposition and transformation of organic carbon.The stand type directly affect the content of organic carbon,the number of microorganisms,and enzymes activity.The analysis of stand type effect on soil organic carbon distribution variation and its relationship with microorganisms and enzymes activity is of great significance to study the distribution regularity of organic carbon in forest soil and analyze its more critical Influencing factors.In this study,five typical forest lands were selected,such as Chinese arborvitae(Platycladus orienlalis),Chinese pine(Pinus tabulaeformis),Chinese white poplar(Populus tomentosa),Black poplar(Populus nigra)and sparse woodland in the Qingxiling tombs region of Hebei Province.The measurement of organic carbon,microbial biomass carbon,microbial quantity(including bacteria,fungi and actinomycetes)and enzyme activity(including sucrase,?-glucosidase,amylase and catalase)in soil profiles of 0?10 cm,10?20 cm and 20?30 cm were carried out.We analyzed the relationship between soil organic carbon,microbes and enzyme activity by using statistical analysis and regression models etc.,revealed the distribution regularity of soil organic carbon and microbial biomass carbon,inquired soil enzyme activity and microbial number distribution characteristics,explore the correlation between soil enzymes and microorganisms and organic carbon,The main research results are as follows:(1)The different stand types had a significant impact on organic carbon and microbial biomass carbon.The highest average organic carbon content in the soil profile is 49.68 g/kg in Chinese arborvitae while the lowest is only 20.37 g/kg in sparse woodland.The highest microbial biomass carbon content is 245.66 mg/L in Chinese arborvitae,and the sparse woodland is only 73.35 mg/L as the lowest.On the soil profile of 0?30 cm,thesoil organic carbon and microbial biomass carbon of the five stand types all decreased significantly with the increase of soil depth,and had obvious vertical distribution characteristics.(2)The different stand types had a momentous impact on the number of microorganisms.The average number of microorganisms on the soil profile is the highest in Chinese arborvitae,The average number of bacteria and fungi was the highest in Chi-nese arborvitae forest land.And the five stand types of soil microbial quantity decreased with the increase of soil layer depth.Except for the number of actinomycetes is no significant downward trend in Chinese pine,the number of microorganisms in any other four stand types decreased significantly.The number of microorganisms in five stand types soil were significantly different in the 0?10 cm soil layer,but there was no significant difference in the 20?30 cm soil layer,which means that the microorganisms was more sensitive in the 0?10 cm soil layer.(3)The different stand types had a powerful effect on enzyme activity.The average activity of the four enzymes we tested on the soil profile was the highest in Chinese arborvitae.Four enzymes activities in five stand types decreased with the increase of the depth of the soil layer,and the activities of invertase,?-glucosidase and amylase decreased significantly.The activity of catalase in black poplar had shown a very significant decline while the other four stand types of had not shown significant significance.The activities four enzymes were the highest in the 0-10 cm Chinese arborvitae soil layer and the lowest in the 20?30 cm sparse woodland soil layer except the amylase activity was highest in the 20?30 cm Chinese pine soil layer.(4)Correlation analysis of the organic carbon content in the five stand types with microbial biomass carbon,microbial quantity and four enzyme activities,the results showed that the microbial biomass carbon,microbial quantity and four enzyme activities were all related to the soil organic carbon content as a very significant positive correlation.Further regression analysis showed that there was a more significant linear relationship between the number of fungi,amylase activity and the soil organic carbon content.The above research results showed that the stand types had a significant influence on the organic carbon,the number of microorganisms and enzyme activity.The influence of microorganisms number and enzyme activity affected by the content of organic carbon in different stand types had obvious regularity.The forest soil organic carbon content decreased significantly with the increase of soil depth.The forest soil microbial biomass carbon content,bacteria and fungi number,amylase activity,invertase activity and?-glucosidase activity decreased significantly or very significantly with the increase of soil depth.The number of fungi and amylase were the key factors affected the soil organic carbon content of the forest land.Catalase,Invertase,?-glucosidase and amylase.as well as the number of bacteria,actinomycetes and fungi were all important factors affected soil organic carbon.