Study On The Relationship Between Plant And Microbial Diversity In Peatland And Its Impact On Carbon Emissions Under Climate Warming

Northern peatlands serve as a crucial carbon storage reservoir and are highly responsive to global changes and human activities.Recent years have seen shrub vascular plants in this system expand rapidly as a community response to climate warming.Unfortunately,this expansion has been accompanied by losses in the number,coverage,and diversity of cryptophytes like peat moss and lichens.These changes have the potential to significantly impact the composition,abundance,and diversity of soil microbial communities,which can ultimately affect the ecosystem services and functions of peatlands.However,most current research has focused on the direct effects of warming,with less consideration given to the processes of plant community adaptation to the environment,and a lack of empirical data to assess the role of plant diversity and functional types.To further understand this phenomenon,a research study was conducted using a typical continuous permafrost peatland located in the Greater Xing’an Mountains.By conducting in-situ plant removal field observations,as well as microcosm plant and 3.4℃warming control experiments,we were able to investigate and reveal the effects and mechanisms of plant functional groups,species diversity,and temperature on soil microbial functional diversity and carbon greenhouse gas emission flux.The main conclusions of this study are as follows:（1）Different functional plant groups have significant differences in their effects on soil microbial community functional diversity.The rhizosphere microorganisms in pure herbaceous plant treatments exhibit higher levels of carbon metabolism and diversity indices,with a preference for amino acids and carboxylic acids as carbon sources.In contrast,the dominant communities of shrubs and mosses show lower levels of carbon metabolism,mainly utilizing polymers and phenolic compounds as carbon sources.The positive correlations between nutrient environmental parameters（soil DOC,NH₄⁺-N,and NO₃^--N concentrations）and enzyme activities（β-xylosidase,β-glucosidase,and cellulase）with microbial functional diversity indices indicate that the functional characteristics of dominant plant communities play a crucial role in modulating microbial functional diversity and carbon metabolic activity.（2）The response of microbial activity,substrate utilization,and diversity to plant diversity changes far outweighs the effect of warming.High species diversity treatments often exhibit stronger carbon metabolic activity,with amino acids,carboxylic acids,and carbohydrates being the dominant carbon sources,accounting for over 60%.SEM analysis reveals that plant species diversity can indirectly enhance soil microbial activity by increasing aboveground and belowground biomass.Additionally,plants from the Cyperaceae family,such as Carex globularis,have a positive impact on microbial carbon metabolic activity and functional diversity,while mosses have an inhibitory effect.This suggests that the role of species diversity can also be explained through the presence of specific plant functions.（3）The range of CO₂ emission rates from peatlands under non-warming and warming environments are 1.38±0.18～44.12±6.29 and 3.77±0.63～46.25±6.62mg C m^-2 h^-1,respectively,with significant temporal dynamics.Climate warming significantly promoted the average CO₂ emissions during the observation period,increasing from 14.10±0.82 to 19.57±1.23 mg C m^-2 h^-1.Furthermore,plant species diversity also has a positive effect on CO₂ emissions,with mixtures of 3 and 4 species increasing emissions by 35.60%,62.12%,and 41.18%,48.71%,respectively,under non-warming and warming environments,compared to monoculture treatments.However,there was no significant synergistic effect between warming and plant diversity on CO₂ emissions.Analysis showed that plant biomass,plant physiological processes,soil DOC,phenolic compound concentration,microbial carbon source utilization efficiency,and functional diversity are important environmental factors affecting CO₂ changes.（4）The CH₄ emission flux from peatlands also exhibits temporal dynamics,with a range of 2.72±2.36 to 319.55±96.22 and 6.07±3.09 to 289.51±37.36μg C m^-2 h^-1under non-warming and warming conditions,respectively.Although the temperature increases effectively increased CH₄ emissions in 2020,the warming in the following year significantly reduced the average CH₄ emissions from 104.98±8.60 to 61.69±8.46μg C m^-2 h^-1.Compared to single species,the mixed treatments of 3 and 4 species showed significant increases of 35.18%and 88.67%at normal temperature,and increased by 80.50%and 129.01%under warming conditions,respectively.More importantly,warming significantly reduced the CH₄ emission flux of single and double species treatments by 43.19%and 50.78%respectively in 2021,but had a weaker effect on 3 and 4 species treatments.Analysis shows that soil moisture,DOC concentration,and microbial carbon metabolism activity are important environmental factors affecting CH₄ changes.Additionally,species diversity and biomass can also indirectly affect CH₄emissions through key species such as the aeration tissue characteristics of Carex globularis.These research findings indicate that the increase in species diversity under the context of climate warming,especially the expansion of vascular plants,can strongly affect the microbial diversity and carbon emissions flux of peatlands,and generate potential feedback on the future climate environment.When predicting and assessing carbon greenhouse gas emission fluxes from northern peatlands,more consideration should be given to the diversity changes caused by the expansion of vascular plants and their effects on microbial communities,particularly in the context of future climate warming.