Data from: Soil organic matter quantity and quality shape microbial community compositions of subtropical broadleaved forests

As two major forest types in the subtropics, broadleaved evergreen and broadleaved deciduous forests have long interested ecologists. However, little is known about their belowground ecosystems despite their ecological importance in driving biogeochemical cycling. Here, we used Illumina MiSeq sequencing targeting 16S rRNA gene and a microarray named GeoChip targeting functional genes to analyze microbial communities in broadleaved evergreen and deciduous forest soils of Shennongjia Mountain of Central China, a region known as “The Oriental Botanic Garden” for its extraordinarily rich biodiversity. We observed higher plant diversity and relatively richer nutrients in the broadleaved evergreen forest than the deciduous forest. In odds to our expectation that plant communities shaped soil microbial communities, we found that soil organic matter quantity and quality, but not plant community parameters, were the best predictors of microbial communities. Actinobacteria, a copiotrophic phylum, was more abundant in the broadleaved evergreen forest, while Verrucomicrobia, an oligotrophic phylum, was more abundant in the broadleaved deciduous forest. The density of the correlation network of microbial OTUs was higher in the broadleaved deciduous forest but its modularity was smaller, reflecting lower resistance to environment changes. In addition, keystone OTUs of the broadleaved deciduous forest were mainly oligotrophic. Microbial functional genes associated with recalcitrant carbon degradation were also more abundant in the broadleaved deciduous forests, resulting in low accumulation of organic matters. Collectively, these findings revealed the important role of soil organic matter in shaping microbial taxonomic and functional traits.作为亚热带地区的两类主要森林类型，常绿阔叶林与落叶阔叶林长期以来备受生态学家关注。尽管二者在驱动生物地球化学循环中具有重要生态意义，但目前学界对其地下生态系统的认知仍较为匮乏。本研究针对16S rRNA基因采用Illumina MiSeq测序，并借助名为GeoChip的功能基因微阵列（GeoChip），对中国中部神农架地区的常绿阔叶林与落叶阔叶林土壤微生物群落进行分析。该区域因生物多样性极为丰富，被誉为"东方植物园"。研究发现，相较于落叶阔叶林，常绿阔叶林的植物多样性更高，土壤养分也更为丰富。与"植物群落塑造土壤微生物群落"的预期相悖，本研究发现，决定微生物群落结构的最佳预测因子是土壤有机质的数量与质量，而非植物群落特征参数。放线菌门（Actinobacteria）作为富营养型菌群，在常绿阔叶林土壤中的丰度更高；而疣微菌门（Verrucomicrobia）作为寡营养型菌群，则在落叶阔叶林土壤中更为富集。微生物操作分类单元（OTU，Operational Taxonomic Unit）关联网络的密度在落叶阔叶林土壤中更高，但模块化程度更低，这反映出其对环境变化的抵抗力较弱。此外，落叶阔叶林土壤微生物群落的关键OTU主要为寡营养型类群。与难降解碳降解相关的微生物功能基因，在落叶阔叶林土壤中的丰度也更高，进而导致该区域土壤有机质积累量较低。综上，本研究结果揭示了土壤有机质在塑造微生物群落分类学与功能性状中的核心作用。