Soil Greenhouse Gas Emission And Its Influencing Factors From Temperate Deciduous Broad-leaved Forest And Tropical Mountain Rain Forest

Increased concentrations of greenhouse gases,such as atmospheric CO₂,CH₄ and N₂O,are the direct cause of warming.The deciduous broad-leaved forest in the temperate zone of Baotianman in Henan province?BTM?and the tropical mountain rain forest in Jianfengling of Hainan province?JFL?are typical forest vegetation types,located in the climate transition region,and also the region most sensitive to climate change.In this study,the two typical forest types of soil were selected as research objects to explore the biotic and abiotic factors influencing the greenhouse gas emission or uptake of CO₂,CH₄and N2O of the two typical forest types of soil.In this study,the emission or absorption of CO₂,CH₄ and N₂O in the soils of BTM and JFL were measured for two consecutive years using the static boxer-meteorology chromatography in situ,and the dynamic changes and influencing factors of the three greenhouse gases in four seasons were analyzed.Through 16S rRNA Illumina Hiseq 2500 high-throughput sequencing method,the composition,diversity and function of the bacterial community in the soils of BTM and the JFL were studies.Major research progress has been made as follows:1.Clarified the dynamic change rules of greenhouse gas emissions of two typical forest soils.The results of analysis showed that both forest types were sources of CH₄ sink,CO₂ and N₂O.The annual mean values of CO₂ and N₂O emission from soils of BTM were respectively214.7±30.7 mg m^-2 h^-1 and 0.05±0.02 mg m^-2 h^-1,and the annual mean values of CH₄ uptake by soil were 0.15±0.02 mg m^-2 h^-1.The annual mean values of CO₂ and N₂O in the soil of JFL were 179.6±28.2 mg m^-2 h^-1 and 0.04±0.01 mg m^-2 h^-1,respectively,and the annual mean values of CH₄ absorbed by the soil were 0.06±0.02 mg m^-2 h^-1.2.Defined abiotic factors of greenhouse gas emissions from forest soil.At BTM,soil CO₂emission has a significant relationship with temperature extremely?P<0.01?,pH,NO₃^--N?P<0.05?.The CO₂ emission in the tropical rain forest of JFL is only extremely related to the soil water filled pore space?WFPS??P<0.01?.Among the 11 measured soil physical and chemical factors,water-filled pore space,total carbon and microbial biomass carbon were the main factors to control methane emission from the soil of BTM?P<0.05?.At JFL,there was no significant correlation between soil CH₄ flux and any soil physical and chemical factors?P>0.05?.In the two forest types of soil,there was no significant relationship between N₂O emission and the 11 measured physical and chemical factors measured?P>0.05?.3.Revealed the mechanism of soil microbiology driving greenhouse gas emissions of two typical forest soils.After high-throughput sequencing,we obtained 51,137 operational taxonomic units and classified them into 44 phyla and 556 known genera.The composition of bacteria in the two forest types of soil was similar at the phylm level,with the highest abundance of Proteobacteria and Acidobacteria.At the bacterial level,we detected the methane-related Candidatus Methylacidiphilum and Methylotenera,Methylobacterium and Methylovirgula.One genus related to nitrous oxide was detected?Planctomyces?.The relative abundance of methane-oxidizing bacteria and methylotrophic bacteria was not significantly different between the four seasons in the two forest types of soil?P>0.05?,and the relative abundance of methane-oxidizing bacteria and methylotrophic bacteria at BTM in all seasons was higher than that at JFL.There is no significant difference between Planctomyces in each season in both forest types of soil,and there is no significant difference between the seasons in the same sample?P>0.05?.There was no significant difference in the annual bacterial Shannon index between BTM and JFL?P>0.05?.Except autumn,the bacterial Shannon index at BTM was significantly higher than that JFL?P<0.05?.4.Predicted the functions related to carbon and nitrogen cycle in soil of the two typical forest types soils.After FAPROTAX function prediction,BTM and JFL soil bacterium function group,we found a total of 12 functions related to the nitrogen cycle,the denitrification including nitrate denitrification,nitrate denitrification,nitrite denitrification,nitrous oxide denitrification these three functions at BTM and JFL,there were significant differences?P<0.05?in the summer,autumn and winter.A total of eight functions related to the carbon cycle,photoautotrophy including anoxygenic photoautotrophy S oxidizing,anoxygenic photoautotrophy,the two functions at BTM and JFL had significant difference?P<0.05?in winter and summer.As predicted by PICRUSt,at Level 2,only energy metabolism in spring and summer of BTM had significant differences?P<0.05?,while amino acid metabolism,polysaccharide biosynthesis and metabolism and lipid metabolism had no significant differences between the two forest types of soil?P>0.05?.This study provides a reference basis for understanding the greenhouse gas flux of CO₂,CH₄ and N₂O at BTM temperate deciduous broad-leaved forest and the tropical forest of JFL in different climate zones and provided quantative information and references for the future study.Data support of biotic and abiotic factors was provided for studying the carbon and nitrogen cycle models and CO2,CH4 and N2O model research of the two typical forest types.This study provides a theoretical explanation of the difference of carbon and nitrogen cycle functions between the two typical forest types.