The Ecological Effects Of Elevated Carbon Dioxide Concentrations On Communities Of Meso-Micro Soil Fauna And Soil Microbial In Honghe Nature Reserve

In recent 100 years,the rapid development of the industrial revolution and the intensification of human activities,the atmospheric carbon dioxide concentrations increased rapidly.At current growth rates,carbon dioxide concentrations are expected to reach 550μmol·mol-1 by mid-century and over 700 μmol·mol-1 by the end of the century.The elevated atmospheric carbon dioxide concentrations drived the photosynthesis of plants and changed the photo-assimilated carbon input into the ground.The increase of photosynthate leads to the change of community structure and ecological function of soil animals and soil microorganisms.Recently climate change had brought a series of negative effects on the regional ecological environment and biodiversity,threaten the land and wetland ecological system at the same time.In this study,we collected soil samples from field situ monitoring station of wetland under global change in Honghe Nature Reserve.A combination method of Tullgren funnel,qPCR and Illumina Miseq sequencing.We chosed meso-micro soil animals and soil microorganisms as research objects and had taken soil samples and in April,June and September of 2018,and carried on the experiment to analyze the community characteristics of meso-micro soil animals and soil microbial under elevated carbon dioxide concentrations.To explain the ecological impact on communities soil organisms belowground under elevated carbon dioxide concentrations.The main results are as follows:(1)We got 86 class 9848 individuals for meso-micro soil animals in different seasons,the dominant groups were Sminthuridae and Chironomidae larvae.We studied the effects of community composition and diversity patterns of meso-micro soil animals under elevated carbon dioxide concentrations in different seasons.The results indicated that the individuals and groups of meso-micro soil animals increased with the elevated of carbon dioxide concentrations in different seasons.The alpha diversity index of meso-micro soil animals increased with the elevated of carbon dioxide concentrations,while the Beta diversity index decreased.RDA analysis showed that CO2 concentrations,soil organic matter and total phosphorus had great influence on the composition and distribution of meso-micro soil animal communities.In general,different carbon dioxide concentrations,different seasons and the interaction of different carbon dioxide concentrations and different seasons all had significant effects on alpha diversity index and beta diversity index of meso-micro soil animals communities.(2)The elevated carbon dioxide concentrations changed the structure and composition of soil microbial community in different seasons,but had no significant influence on the diversity pattern of soil microbials.At the phylum classification level,the common dominant group of soil bacterial communities were Proteobacteria,Acidobacteria,Chlorobacteria,Actinomycetes,Nitrobacteria and Blastomonas,while the common dominant group of soil fungal communities were Ascomycota and Basidiomycota in different seasons.The response of soil microbials had differeces under elevated carbon dioxide concentrations in different seasons,alpha diversity of soil microbial community had no significant response to elevated carbon dioxide concentrations,and the seasonal differences of beta diversity index included βJAC and βSOR was spring>autumn>summer at the same time.But the soil microbial community had different responses with the increasing of carbon dioxide concentrations in different seasons,we also found turnover components are over 60%under elevated carbon dioxide concentrations in different season.That showed that variation of community composition of soil microbials center on species replacement under elevated carbon dioxide concentrations in different seasons.Carbon dioxide concentrations,soil pH,soil organic matter,total nitrogen and mostiure affected the distribution of soil bacterial community as the main environmental factors,while soil pH and mostiure affected the distribution of soil fungi community as the main environmental factors.(3)The seasonal variations and different carbon dioxide concentrations led to the change of interaction of meso-micro soil animals and the dominant microorganisms group.The interaction of between meso-micro soil animals communities and soil bacterial communities was high correlation with Shannon-Wiener index and Simpson index under different of seasonal variations and carbon dioxide concentrations.Meso-micro soil animals and soil fungal had a negative correlation with diversity index in the treatment of AC and EC2 in spring and summer,but had positive correlation in EC1 treatment.The Simpson index of them had a positive correlation under different carbon dioxide concentrations in spring and summer,but had some differences in autumn and other seasons.The interaction between meso-micro soil animal communities and soil microbials were negative correlations with the beta diversity included PJAC and βSOR under different carbon dioxide concentrations.(4)According to the different response of meso-micro soil animals and soil microorganisms to the elevated carbon dioxide concentrations in different seasons and selected key indicator species.Trombidiidae and Thetocepheidae can be used as indicator species in meso-micro soil animals community,Rhizoscyphus and Solirubrobacterales can be used as indicator species in spring,Ardenticatenia and Stephanonectria can be used as indicator species in summer,Anaerolineae and Sugiyamella can be used as indicator species in autumn in soil microorganism community.In the management of nature reserves,long-term monitoring of the indicator species that can give early warning of the impact of elevated carbon dioxide concentrations and other kinds of climate change,put forward that reducing human interference,improving the construction of nature reserves network and strengthening regional connection at the same time.The above results showed that the community composition and distribution pattern of meso-micro soil animals and soil microbes had obvious differences due to seasonal variations,elevated carbon dioxide concentrations and different soil environment,especially that the community of meso-micro soil animals are more significant response to elevated carbon dioxide concentrations.Soil organic matter affected the community of meso-micro soil animals rank only second to carbon dioxide concentrations,soil pH is the main factor drived the community distribution pattern of soil microbials.Strengthening indicator species monitoring in nature reserves and building a nature reserve network can enhance the protection against climate change.