灌木林土壤古菌群落结构对地表野火的快速响应

Rapid response of shrubbery soil archaeal communities to surface wildfire

为了评价地表野火对土壤古菌群落结构的即时影响,在灌木林火发生18h后,于火烧迹地和未烧地采集土壤样品,通过构建两个土壤古菌16S rDNA基因文库,研究火烧后小时尺度下土壤古菌群落结构的变化。从火烧和对照未烧土壤古菌文库中共得到19个古菌的操作分类单元(Operation taxonomic units,OTUs),其中对照未烧林地土壤文库中存在9个OTUs是火烧土壤中缺失的类群,占克隆总数的5.91%。未烧林地中3个优势古菌克隆YM ar-F25(GQ304791)、YMar-F32(GQ304792)及YMar-F21(GQ304789)系统发育归类为泉古菌门亚群G roupⅠ,分别占克隆总数的15.50%,18.18%,41.36%;而在火烧迹地中这3个古菌分类群仍为优势群,分别占克隆总数的15.59%,22.58%,46.24%。多样性指数分析显示对照土壤古菌文库Shannon-Wiener指数为1.87,而火烧土壤古菌文库为1.40。结果表明,在小时尺度上,高强度灌木林火使土壤古菌多样性立即降低,低丰度土壤古菌种群对火干扰敏感,高丰度古菌的种群结构火烧后无明显变化。

This study was conducted to evaluated the immediate influence of surface wildfire on the soil archaeal community structure in a shrubbery.Burned soils were sampled 18 hours after a shrubbery fire in Yumin county of Xinjiang,Northwest China,and control soils were sampled from a unbured shrubbery next to the fire-impacted areas.Two archaeal 16S rDNA gene clone libraries were generated from total genomic DNA in the two soils.Nineteen archaeal operation taxonomic units（OTUs） were obtained from the two soils clone libraries by restriction fragment length polymorphism（RFLP）analyis,and nine of them were only detected in the unburned soils and accounted for 5.91% of total clones,being absent in the burned soils.Three dominant archaeal taxonomic units YMar-F25（GQ304791）,YMar-F32（GQ304792） and YMar-F21（GQ304789） fell into subgroupⅠof Crenarchaeota,accounting for 15.50%,18.18% and 41.36% of the total clones respectively in the unburned soil library.Immediately after the fire,the three taxonomic units were still dominant in the burned soil library,accounting for 15.59%,22.58% and 46.24%.Shannon-Wiener index of unburned soil archaeal 16S rDNA gene clone library was 1.87,and the burned soil library was 1.40.The results suggested when the time after high severity shrubbery fire was at hourly scale,diversity of soil archaea was lower in burned site than the control site,groups of archaea with low abundance were more sensitive to fire disturbance than those with high abundance.Community structure of the groups with high abundance was not altered significantly after fire.