内蒙古草地土壤细菌生物多样性与生产力的相关关系分析

Relationship between soil bacteria diversity and productivity from an Inner Mongolia grassland

以内蒙古草地土壤细菌为研究对象,在3个不同的空间尺度上采集土壤样品,探讨内蒙古草地土壤细菌群落生物多样性与生产力之间的关系.内蒙古草地土壤细菌物种丰富度很高,达到上千个实用分类单元(OTUs);分属14个门,其中放线菌、变形菌和酸杆菌相对多度之和达80%以上.细菌群落生物量(每克干土DNA条带数)介于2.91×108~4.28×109条·g-1.稀化处理后的细菌OTUs数目、香侬-威纳指数和辛普森指数分别为721.79~1 023.47、5.84~6.21和82.98~229.02.但是,土壤细菌群落的生物多样性与生产力之间并不存在显著的相关关系,并且该模式与地理尺度无关.该结果暗示着该地区土壤细菌可能是中性或者近中性共存.

Many studies of plants and animals have reported positive or hump-shaped relationships between biodiversity and productivity.Such studies in microorganisms are still rare,most of which focus on aquatic ecosystems.In this research,we implemented a field survey to analyze the relationship between soil bacteria diversity and productivity on three different geographic scales in the Inner Mongolia grassland.Taxa richness of bacteria in the Inner Mongolia grassland was high,thousands of operational taxonomic units(OTUs)were defined.Bacterial sequences belonged to 14 phyla.Actinobacteria,Proteobacteria and Acidobacteria were dominant,comprising more than 80% of all the sequences.The biomass of soil bacteria was between 2.91×108~4.28×109 DNA sequences per gram dry soil.The number of OTUs,Shannon-Wiener index and Simpson’s index were 721.79~1 023.47,5.84~6.21 and 82.98~229.02 respectively after rarefaction.However,there were no significant correlations between them and bacteria productivity,and these patterns were not affected by geographic scales.These results may suggest neutral or nearly neutral coexistence of soil bacteria in Inner Mongolia grasslands.