Study On The Nutrient Limitation And Linkages Between Above-Belowground Communities By Fertilization

Above-belowground linkages not only influenced ecosystem function but also correlated with global climate change and ecosystem balance.In the past,researches were usually concentrated on the plant community.With advances in technology,more and more studies concentrated on the linkages of above-belowground which bases on plant-soil-microorganism interactions.Special environment,i.e.,low temperature,high altitude and intense radiation,make Qing-hai Tibet plateau in an oligotrophic state for a long time,which is sensitive the climate change.Fertilization,an usual way to manage grassland,could promote primary production.Meanwhile,this method also influences community and ecological functions.In conclusion,the research of above-belowground communities’ s nutrient limitation and their linkages could provide help for the understanding of future ecosystem changes.Our study built a concept model about above-belowground communities’ s nutrient limitation types.coupled plant and microbial communties by SEM(Structural equation model)and adopted high-through pyrosequencing and q PCR binding method,The purpose of this study was to explore the nutrient restriction of archaeal,bacterial and plant community and their linkages in different fertilizer gradients of nitrogen(N),phosphorus(P)and nitrogen plus phosphorus(NP)of alpine meadow in Qing-hai Tibet plateau.Results are shown below:1.Fertilization influence on the diversity of soil microbial communityPyrosequencing results showed that there were 182143 archaeal sequences ranked to 355 OTUs and 276350 bacterial sequences ranked to 6246 OTUs were detected.Community diversity of bacteria was significantly higher than archaea.Thaumarchaeota acted as dominate phylume and Proteobacteria,Acidobacteria and Actinabacteria were the predominantly phyla in bacterial community.High gradient NP and P addition increased archaeal and bacterial α diversity,respectively.2.Nutrient limitation types and linkages between above-belowground communities Based on the model of nutrient limitation,archaeal taxa(21 OTUs),bacterial taxa(89 order/sub-orders)and plant species(21 species)were classified to thirteen nutrient limitition types(categorized to five big nutrient limitation types).Relatively,the types in archaeal community which mainly limited by P were equality than bacteria which mainly limited by other resources.The results showed that plant community was limited by N,archaeal community was limited by P and bacterial community couldn’t categorized to any type.Thus,our results againly verified the necessary to research nutrient limitation in taxa level.No matter aboveground or beloground community,P and N limited taxa were negatively and positively correlated with AN:AP,respectively.Correlation analysis results showed that the competitiveness of plant were stronger than microorganism.There were significantly positive relationships when the taxa nutrient limitation of archaea and bacteria were in accordance with plant species.It’s means that fertilization could remit the competition between plant and microorganism.Nutrient response of archaeal and bacterial taxa had no notablely phylogenetic signal.However,archaeal and bacterial taxa responses to phosphorus and nitrogen appeared functional convergency,which explained by that nutrient response have no phylogenetic convergency.3.Plant-soil-microorganism linkagesArchaeal community was indirectly effected by plant community when nitrogen added(λ= 0.900),but bacterial community was effected by fertilization directly(λ=-0.841).When phosphorus added,archaeal community directly response to fertilization(λ=-0.612).Archaeal(λ= 0.621)and bacterial(λ= 0.462)community were directly responsed to nitrogen plus phosphorus addition.Thus,different fertilizer treatments influenced above-belowground communties significantly.P addition mainly effected arcraeal community.Instead of indirectly plant impact,NP addition directly influenced archaeal and bacterial communities.