The Effects Of Biochar And Ectomycorrhizal Fungi On The Decomposition Of Forest Soil Organic Carbon

Forest soil organic carbon plays an important role in global climate change,which controls the balance of CO₂ concentration in the atmosphere.At present,the distribution and dynamic change of soil organic carbon pool is the most important effect factor on the uncertainty of global carbon cycle.As a solid carbon material,biochar can improve soil physicochemical properties,change the microbial community structure,and affect the process of the cycle of soil organic carbon.As an important component of the microbial community,ectomycorrhizal fungi?EMF?play the vital role in organic carbon cycling in forest soil.This study is based on the combination of laboratory and field experiments to research the changes of soil microbial biomass,organic carbon related enzyme activities in forest soil,the effect of biochar on the microbial activity,organic carbon related enzyme activities and structure and diversity of EMF communities,the role of EMF in organic carbon decomposition in forest soil.The results of this study will provide a scientific basis for the study and management of the cycle of the organic carbon in forest soil.Major results are listed as follows:?1?Biochar had no obvious effects on the MBC content in Quercus acutissima Carruth and Platycladus orientalis soil.However,biochar had no significant effect on the MBC content in the two forest soils from the third days to the end of the experiment.Biochar increased the microbial respiration rate significantly in Q.acutissima Carruth soil.The soil respiration rate after biochar addition was about 1.65 times as much as that of the original soil,but no significant effect was observed in P.orientalis soil.?2?There was no significant difference in MBC in summer and autumn samples in the early stage of experiment.The MBC content in summer soil was lower than that in autumn soil in third days and the content of MBC in seventh days was higher in autumn.There was no obvious difference in the content of microbial biomass carbon in two seasons in the later stage of experiment.The content of MBN in summer was significantly lower than that in autumn in the early stage of experiment.There was no clear difference in soil MBN from third to fourteenth days in the two seasons,the content of MBN in twenty-eighth days was higher in summer.?3?Biochar increased the observed number,Simpson index and chao1 index of EMF in different treatments greatly,which demonstrated that biochar strongly increased the diversity of EMF in Q.acutissima soil.PCoA analysis showed that biochar significantly changed the structure of EMF community in Q.acutissima soil.Biochar reduced the activity of acid phosphatase by 12.55% and increased the activity of ?-1,4-xylosidase by 29.8% in samples without sand barrier,increased the activities of polyphenoloxidase,cellobiohydrolase and ?-1,4-glucosidase by 45.86%,83.61% and 29.64%,and reduced the activity of ?-1,4-xylosidase by 43.66% in sand barrier samples in summer.Biochar reduced the activities of polyphenoloxidase and cellobiohydrolase by 27.82% and 17.27% and increased the activity of ?-1,4-xylosidase by 33.57% in samples without sand barrier,increased the activities of polyphenoloxidase and cellobiohydrolase by 25.16% and 76.11% and reduced the activity of ?-1,4-xylosidase by 31.46% in sand barrier samples in autumn.?4?The activities of enzymes related to organic carbon decomposition in spring were significantly different from those in other seasons.The activities of polyphenoloxidase,cellobiohydrolase and ?-1,4-xylosidase were higher in spring soil than in other seasons by 57%,63% and 34%,respectively.The activity of ?-1,4-xylosidase was 143% higher in spring root than that in other seasons.The activities of acid phosphatase,polyphenoloxidase,cellobiohydrolase,?-1,4-xylosidase and ?-1,4-glucosidase were higher in spring humus than in other seasons by 110%,67%,33%,116% and 199%,respectively.?5?After the ITS pyrosequencing of Q.acutissima soil,root and humus,six fugal phylums were observed.Ascomycota and Basidiomycota were the main component of the fungal communities,which accounted for more than 90%.In addition,other phylums such as Chytridiomycota and Glomeromycota was detected in individual samples.The abundance of fungi in soil and humus was comparability.In summer samples,the relative abundance of Ascomycota?Basidiomycota and Zygomycota was 71.3%,20.77% and 3.67% in soil,67.3%,20.47% and 9.07% in humus,however,6.55%?90.17% and 0% in root.In autumn samples,the relative abundance of Ascomycota?Basidiomycota and Zygomycota was 42.6%,50.3% and 2.7% in soil,40.83%?52.9% and 4.43% in humus,however,25.63%?73.87% and 0.43% in root.There were significant differences in EMF abundance in different seasons between soil,root and humus.The most abundant EMF were Russula in soil,Lactarius in humus and Lepista in root in summer samples.The most abundant EMF were Russula in soil,humus and root in autumn samples.?6?There was a close relationship between EMF community and the activities of acid phosphatase,?-1,4-xylosidase and ?-1,4-glucosidase.The Ganoderma,Russula and Phialocephala in the ectomycorrhizal fungi community were negatively correlated with the activities of acid phosphatase,?-1,4-xylosidase and ?-1,4-glucosidase in summer.However,The Ganoderma,Lycoperdon,Lactarius,Russula,Phialocephala and Cenococcum in the ectomycorrhizal fungi community were negatively correlated with the activities of acid phosphatase,?-1,4-xylosidase and ?-1,4-glucosidase in autumn.