Microbiological Mechanisms Of Litter Inputs On Soil CO₂ And N₂O Emission

Forest litter is the product of plant tissue senescence,death or regeneration,and it is also an important factor affecting soil organic matter.The decomposition of litter will affect the changes of soil nutrients and microbial characteristics,and further affect soil CO₂and N₂O emission.The study relied on Sanming Forest Ecosystem and Global Change Station in Fujian Province.Six treatments were set up in the incubation experiment,including Pinus massoniana lamb litter+Pinus massoniana lamb soil(PM+PM)?Lindera communis hemsl litter+Pinus massoniana lamb soil(LH+PM)?Liriodendron chinensis litter+Pinus massoniana lamb soil(LC+PM)?Pinus massoniana lamb litter+Pinus massoniana lamb soil(PM+LC)?Lindera communis hemsl litter+Pinus massoniana lamb soil(LH+LC)and Liriodendron chinensis litter+Pinus massoniana lamb soil(LC+LC).The following main results were obtained:(1)Time and treatment could lead to significant changes in soil ammonium nitrogen.The ammonium nitrogen contents in different treatments all showed a trend of decreasing first and then increasing.The change trend of ammonium nitrogen content was basically consistent with the change trend of mineral nitrogen content.Soil nitrate nitrogen content accounted for a small part of mineral nitrogen content.(2)Time,treatment and their interaction could significantly affect soil CO₂emission rate,N₂O emission rate and cumulative emission CO₂.The CO₂emission rate of the six treatments stabilized after 3 days.The changes of soil N₂O emission rate in different treatments with time decreased first,then increased and then decreased.(3)Time,treatment and their interaction could significantly affect soil microbial biomass carbon content.There was no significant difference in soil bacterial community alpha diversity in different treatments.The soil bacterial community alpha diversity in different treatments was mainly reflected in diversity,but the richness was not significantly affected.(4)The differences in microbial community composition in different treatments might be mainly attributed to Acidobacteria,Proteobacteria,Chloroflexi,Actinobacteria,Ascomycota and Basidiomycota,as evidenced by biomarkers that had significant differences among different treatments using LEf Se analysis.In addition,there were significant differences in soil microbial community groups among different treatments,which might be related to differences in soil nutrients and nutrient strategies of microorganisms.(5)The abiotic driving factors affected the changes of soil CO₂and N₂O emission including ammonium nitrogen(NH₄⁺-N),nitrate nitrogen(NO₃^--N),mineral N,net ammonification rate(R_a),net nitrification rate(R_n)and net mineralization rate(R_m).CO₂emission rate was significantly negatively correlated with R_a,R_nand R_m.Cumulative emission CO₂was significantly negatively correlated with NH₄⁺-N,NO₃^--N and Mineral N;Cumulative emission CO₂was significantly positively correlated with R_a,R_nand R_m.N₂O emission rate was significantly positively correlated with NH₄⁺-N and Mineral N;N₂O emission rate was significantly negatively correlated with NO₃^--N,R_aand R_m.Cumulative emission N₂O was significantly negatively correlated with NH₄⁺-N.The biological driving factors affected the changes of soil CO₂and N₂O emission including Proteobacteria,Chloroflexi,Actinobacteria,Acidobacteria,Ascomycota and Basidiomycota.