Effects Of Dicranopteris Dichotoma On Dissolved Organic Matter And Microbes In Eroded Red Soil

It has great carbon sequestration potential in degraded soil.Dicranopteris dichotoma is a dominant understory plant at Pinus massoniana(PM)plantations in erosive degraded red soil in subtropical China,however,the influence of Dicranopteris dichotoma on soil carbon accumulation is still unclear.In this research,severely eroded land,Pinus massoniana plantations(13a and 30a)restored from severely eroded land,which parent materials were all developed from granite,selected as research objects in Hetian town,Changting,Fujian province.We analyzed the soil organic carbon(SOC)content and storage of Dicranopteris dichotoma covered soil(MQ)and bared soil(CK)under severely eroded land and Pinus massoniana plantation,and through the artificial leaching experiment combining with ultraviolet,fluorescence and PLFA technology,we also observed the quantity and structure of dissoluble organic carbon leached from Dicranopteris dichotoma,the microbial quantity and microbial functional groups,to clarify the effects of Dicranopteris dichotoma on carbon accumulation in degraded red soil.The results of the study has important scientific value to further understand the mechanism of degraded red soil carbon sequestration,and has important significance for ecological restoration and undergrowth management in the red soil erosion area of China.The main conclusions are as follows:(1)The coverage and biomass of Dicranopteris dichotoma in the 13-year-old PM and the 30-year-old PM was significant higher than that in the severely eroded land;SOC content of MQ was significantly higher than that of CK in the three forests(P<0.05);The SOC storage was increasing with the extension of revegetation time.This indicated that the recovery of Dicranopteris dichotoma will increase SOC storage.(2)Through artificial leaching experiments on the fresh leaves and litter of Dicranopteris dichotoma and PM,results show that:the dissolved organic carbon within leaching solution of fresh leaves of Dicranopteris dichotoma is highest,the aromaticity index(SUVA)and humification index(HIX)of dissolved organic matter within leaching solution of litter of Dicranopteris dichotoma are highest.The DOC and romaticity index(SUVA)as well as humification index(HIX)of MQ are significant higher than that of CK.Topsoil(0-10 cm)of soil column is used to study the influence of leaching solution of fresh leaves and litter of Dicranopteris dichotoma and PM on soil,results show that,the DOC content and aromaticity index(SUVA)as well as humification index(HIX)from soil leachate are lower than leaching solution,the DOC interception of CK was significant higher MQ.These results show that with the coverage of Dicranopteris dichotoma during the recovery of PM in erosive degraded red soil in subtropical China where rainfall produce massive DOM,when these DOM enter into soil,they were intercepted through absorption,the accumulation of organic carbon stock was increased consequently.At the same time,after the coverage of Dicranopteris dichotoma at MQ,the aromaticity index(SUVA)and humification index(HIX)of DOM were significant increased,the structure of DOM was more complex,more resistant to decomposed,and also benefit for the accumulation of SOC.(3)The microbial biomass carbon and enzyme activity of MQ were significant higher than those of CK,the total PLFA,bacteria,gram-positive bacteria,gram-negative bacteria,actinomycetes,arbuscular mycorrhizal fungi,fungi fatty acid were higher than those of CK,the ratio of fugal to bacteria of MQ was significant higher than that of CK.The growth and coverage of Dicranopteris dichotoma enhanced the growth and reproduction of microbial,the biomass and activity of microbial were enhanced,the microbial structure was also changed,the increased proportion of fungal in soil microbial would benefit for the accumulation and stability of soil organic carbon,and soil ecosystem could be more stable.