开垦对阿拉尔绿洲盐渍化荒漠土壤微生物群落的影响

Impacts of reclamation on salinization desert soil microbial community:a case study of Alar oasis

近年来,以对天然荒漠进行开垦和耕作为标志的人类活动加速了中国西北干旱荒漠区的绿洲化进程,但这种土地利用方式的改变对干旱荒漠土壤微生物群落特征的影响及其机理尚不清楚。本研究利用qPCR和Illumina Miseq高通量扩增子测序技术对新疆阿拉尔绿洲开垦5年的棉花田(FS)和毗邻的天然荒漠(ND)的土壤细菌、古菌和真菌群落的生物量、多样性和群落结构进行了对比研究,揭示了驱动荒漠土壤微生物群落结构演变的主要因子。结果表明:(1)荒漠开垦为农田后,土壤细菌和真菌群落的生物量显著增加,而古菌群落生物量显著降低;细菌群落多样性明显提高,古菌群落的Shannon多样性指数显著降低,而真菌群落多样性没有显著变化。(2)盐渍化荒漠具有不同于其他干旱荒漠的土壤微生物群落结构,开垦显著改变了其土壤细菌、古菌和真菌的群落结构。其中,放线菌门、绿弯菌门、酸杆菌门、螺旋体菌门和浮霉菌门细菌、乌斯古菌门和芽枝霉门真菌的相对丰度显著增加,而盐纳古菌门的相对丰度则显著降低。(3)土壤电导率(EC)、总有机碳(TOC)、全氮(TN)、全磷(TP)是影响细菌群落结构的关键因子;古菌群落结构的主要影响因子为植被盖度、地上生物量和丰富度、TP和AP;EC是影响真菌群落结构的关键因子。综上所述,盐渍化荒漠开垦后由于其原生植被群落、化学肥料的使用和土壤属性(EC、TP和AP)的改变不同程度地改变了荒漠土壤微生物群落特征。相对而言,细菌群落对土地利用方式的改变响应最为敏感,而古菌和真菌群落的多样性和结构则保持相对稳定。

Recently,human activities characterized by reclamation and cultivation accelerated oasisization of drylands in the northwest China.However,it is still unclear about how such land use changes impact characteristics of soil microbial communities in saline-alkaline desert.By using qPCR and Illumina Miseq high-throughput amplicon sequencing technologies,we conducted a comparative study on soil fungal,bacterial and archaeal community biomasses,diversities and structures in a 5-year-old cotton farmland soil(FS)and an adjacent natural desert soil(ND)in Alar oasis of Xinjiang province.The results showed that:(1)reclamation significantly increased bacterial and fungal biomasses,and decreased archaeal biomass based on qPCR estimation.While most bacterial diversity indices significantly increased and archaeal Shannon index decreased due to reclamation,fungal diversity indices were not significantly changed.(2)An unique microbial community different from other arid desert ecosystem inhabited in the salinization desert.Reclamation significantly changed soil bacterial,archaeal and fungal community structures.Especially,the relative abundances of Actinobacteria,Chloroflexi,Acdiobacteria,Saccharibacteria and Nitrosipirae bacteria,Woesearchaeota_DHVEG-6 archaea and Blastocladiomycota fungi in FS significantly increased,while that of Nanohaloarchaeota archaea significantly decreased compared to that in ND.Soil electrical conductivity(EC),total organic C(TOC),total N(TN),total P(TP)and available P(AP)were the key factors in determining bacterial community structure,vegetation coverage,aboveground biomass and richness,TP and AP were the key factors in shaping archaeal community structure,and EC was the key factors in structuring fungal community.In conclusion,oasisization due to recalmation divergently shifted characteristics of soil microbial community in salinization desert mainly due to changes in virginal vegetation,soil EC,TOC and TN and chemical fertilizers use,therein bacterial community showed the highest sensitivity to reclamation,while archaeal and fungal diversity and structure were relatively stable.