Response Traits Of Soil Microbial Communities To Multi-Factor Environmental Disturbances In The Typical Grassland And Forest Of China

Anthropegenic activities owing with population growth and economic development have caused many environmental issues for natural ecosystems.The comprehensive assessment of environmental disturbances consequences is limited by the lacking of understanding for microbial composition and functions.It is thus necessary to study the microbial response traits to multi-factor environmental disturbances to improve the prediction for future ecosystem changes and implement effective managements.This study focused on the main environmental issues of typical grassland,forest and mangrove ecosystems in China.Wind erosion,grazing,nitrogen deposition and seawater eutrophication were simulated in fields or greenhouse,and samples were collected to analyze the changes of functional community structure and microbial taxanomic composition by GeoChip and high-throughput sequencing targeting 16 S rRNA genes,respectively.A number of edaphic physicochemical parameters and vegetation attributes were also collected.This study aims to elucidate the response traits of soil microorganisms to typical environmental disturbances in different ecosystems.Five main conclusions are obatained in this study:(1)Wind erosion and soil deposition in semi-arid grassland significantly changed the soil microbial communities.Most of microbial functional genes associated with nutrient cycling were decreased or unaltered by both erosion and deposition,probably arising from acceleration of organic matter mineralization.Furthermore,significant correlations between soil nutrients and functional structure and functional genes demonstrated close relevance of microbial functional traits to nutrient cycling.(2)Microbial functional traits,including both functional genes and functional taxa,can be used as sensitive biomarkers for detecting subtle disturbances of light grazing rather than overall taxonomic traits.(3)In different ecosystems,fungal and bacterial communities showed different sensitivities to nitrogen addition.In the broad-leaved forest,the fungal community showed higher sensitivity to nitrogen addition than bacterial community,however,in mangroves,opposite results were observed.(4)Genes associated with chemically recalcitrant carbon degradation remained unaltered or decreased,which suggested that nitrogen addition could promote soil carbon accumulation potential.(5)Significant antagonistic interactions were observed for 41% percent of nitrogen cycling genes by nitrogen and earthworm addition in broad-leaved forests,while nitrogen addition and temperature increase were synergistic with respect to 16% percent of the microbial taxa in mangrove sediments.These results illustrated the complexity of microbial responses to environmental disturbances in more realistic scenarios and suggested that single-factor studies could not predict all relevant changes in soil microbial communities.This study demonstrats the response traits of microbial taxonomic composition and functional genes to local environmental disturbances in typical grassland and forest soils in China.This study underscores the difficulty in fully anticipating complex responses of microbial communities and highlights the importance of microbial functional response in monitoring environmental disturbance.These findings are important for elucidating microbe-mediated nutrient cycling as well as incorporating microbial community information in assessing the ecological impacts of global change events.