Dynamics Of Soil Respiration And Its Components At Different Successional Stages In The Greater Khingan Mountains

Climate warming has become serious in recent years,which is not only related to human activities,but also related to forest carbon flux.Soil respiration is one of the components in the CO₂ exchange between terrestrial and atmosphere.Therefore,studying the forest succession has certain significance for the carbon cycle model and its underground carbon stock in this study.We selected four different succession stages of grassland(GL),Betula platyphylla forest(BF),Betula platyphylla and Larix gmelinii mixed forest(MF),Larix gmelinii forest(LF)in boreal zone in the Greater Khingan Mountains of northeast China in 2019,and we used trenching method(NR)to distinguish the components of soil respiration,and the influence of litter on soil respiration(NL)was determined by the method of exclusion litter.And analyzed the relationship between soil temperature and moisture with soil respiration at 5 cm of the soil.(1)Succession stages had a significant effect on Rs in the GL,BF,MF,and LF(P<0.05),and there are differences in soil respiration and its components between different successions.The mean soil respiration(Rs)of GL,BF,MF,and LF were 3.11,5.68,5.54,and 4.69?mol.m^-2.s^-1,respectively,Rh were 2.37,4.56,4.31,and 3.50?mol.m^-2.s^-1,respectively,Ra were 0.74,1.12,1.23,and 1.19?mol.m^-2.s^-1,respectively,and the values of Rl in exclusion litter(NL)of GL,BF,MF and LF were 0.20,0.29,0.37,and 0.51?mol.m^-2.s^-1,respectively.(2)The contribution of Ra to Rs about GL,BF,MF,and LF were 23.79%?19.72%?22.20%,and 25.37%,respectively.The contribution of Rh to Rs about GL,BF,MF,and LF were 76.21%?80.28%?77.80%,and 74.63%,respectively.The contribution of Rl to Rs about GL,BF,MF,and LF were 6.43%?5.11%?6.68%,and 10.67%,respectively.The contribution rate of each respiration components of GL,BF,MF,and LF is different(P<0.05).(3)Through the comparison of trench method(NR)and exclusion litter(NL)with the background(CK),it is found that the temperature and moisture under different treatments have changed,but they have a significant impact on soil respiration under different treatments.The soil temperature at 5cm can explain 18.4%?81.9%of soil respiration,and the soil moisture at 5cm can explain 10.3%?63.6%of soil respiration.Indicating that soil temperature has a greater impact on soil respiration than soil moisture.Regarding the Q₁₀ studies,LFQ₁₀>GLQ₁₀>MFQ₁₀>BFQ₁₀in the CK,LFQ₁₀>BFQ₁₀>GLQ₁₀>MFQ₁₀in the NR,and BFQ₁₀>LFQ₁₀>MFQ₁₀>GLQ₁₀in the NL,In addition,we found the Rs Q₁₀>Rh Q₁₀>Rl Q₁₀ in the same succession stage.(4)It was found that Ra was significantly correlated with fine root biomass(P<0.01),and Rs was significantly correlated with fine root biomass forest litter biomass(P<0.05).The abiotic and biotic factors effect soil respiration were differences in the four succession stages due to the vegetation types.And respiratory metabolic quotient was increased with succession.Our results highlight the importance of succession stages for soil respiration and its components,and its significance to the estimating forest carbon sink.