若尔盖高原泥炭沼泽土壤微生物空间分布

Spatial distribution of soil microorganisms in the Zoige Plateau peatland,Southwest China

研究高原泥炭沼泽土壤微生物群落组成特征及空间分布格局对于维护高原湿地生态系统结构及功能稳定性具有重要意义。本研究采集若尔盖核心保护区内沿土壤水平与垂直方向分布的50个土壤样本,利用高通量测序技术,并结合Mantel检验和多元回归模型(MRM)多元回归统计方法,对土壤细菌和真菌群落多样性、局域尺度上的群落结构相似性空间分布特征及驱动因子进行分析。结果表明:若尔盖高原泥炭沼泽土壤中的优势细菌和真菌类群分别为绿弯菌门(在水平和垂直方向上分别占总细菌群落的33.2%和25.1%)和子囊菌门(54.7%和76.4%);水平和垂直方向的微生物群落结构相似性均随采样点空间距离增加而逐渐降低,垂直方向上细菌和真菌群落的周转速率分别为水平方向的8.8和8.6倍。依据群落相对丰度将微生物划分为6个分类群,随着群落中稀有种数量的增加,群落距离衰减斜率降低,且条件性稀有或优势物种(CRAT)与总微生物群落的空间分布特征最相似。Mantel分析表明,土壤有机碳、总氮和活性磷是影响水平方向上细菌和真菌群落分布的关键驱动因子,而土壤有机碳、活性碳、pH值和土壤容重则是决定微生物垂直方向分布的主要因子。MRM分析进一步表明,土壤理化指标和空间距离均对微生物群落构建具有极显著影响,其中土壤因子对微生物群落垂直方向分布的解释度高于水平方向,且土壤因子对微生物群落分布的影响远大于空间因子通过扩散限制产生的影响。综上,高原泥炭沼泽土壤微生物群落具有更明显的垂直方向分布差异及环境响应特征。

Understanding the composition and spatial distribution patterns of microbial communities in plateau peatland soils is crucial for preserving the structural and functional stability of highland wetlands.We collected 50 soil samples from the core conservation area of Zoige peatland along horizontal and vertical distributions to analyze the soil bacterial and fungal diversity by using high-throughput sequencing technology,combined with Mantel tests and multiple regression on matrices(MRM)statistical methods,as well as the spatial distribution characteristics of community structure similarity at a local scale.The results showed that the dominant soil bacterial and fungal groups were Chloroflexi(accounting for 33.2% and 25.1%of the total bacterial community in horizontal and vertical directions,respectively)and Ascomycota(54.7% and 76.4%).The similarity of microbial community structure in both horizontal and vertical directions decreased with increasing spatial distance of the sampling points.The turnover rates of bacterial and fungal communities in the vertical direction were 8.8 and 8.6 times as those in the horizontal direction,respectively.Based on the relative abundance of the communities,we classified microbes into six groups.As the number of rare species in the community increased,the slope of community distance decay decreased.The conditionally rare or abundant taxa(CRAT)category group showed the most similar spatial distribution characteristics to the total microbial community.Mantel analysis indicated that soil organic carbon,total nitrogen,and available phosphorus were key factors driving the distribution of bacterial and fungal communities in the horizontal direction,while soil organic carbon,available carbon,pH,and soil bulk density were the main factors determining the vertical distribution.MRM analysis further showed that both soil physicochemical indicators and spatial distance significantly affected the assembly of microbial communities,where soil factors explained more about the vertical distribution of microbial communities than the horizontal distribution.The impact of soil factors on microbial community distribution was much greater than that of spatial factors through diffusion limitation.In summary,the microbial communities in the plateau peatland soils exhibited more pronounced vertical distribution differences and environmental response characteristics.