Long-term elevated CO2 shifts composition of soil microbial communities in a Californian annual grassland, reducing growth and N utilization potentials.
Long-term elevated CO2 shifts composition of soil microbial communities in a Californian annual grassland, reducing growth and N utilization potentials.
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DOI：
10.1016/j.scitotenv.2018.10.353
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发表时间：
2019-02
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通讯作者：
Sihang Yang;Qiaoshu Zheng;M. Yuan;Z. Shi;N. Chiariello;K. Docherty;S. Dong;C. Field;Yun-fu Gu;J. Gutknecht;B. Hungate;X. Le Roux;Xingyu Ma;A. Niboyet;T. Yuan;Jizhong Zhou;Yunfeng Yang
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作者：
Sihang Yang;Qiaoshu Zheng;M. Yuan;Z. Shi;N. Chiariello;K. Docherty;S. Dong;C. Field;Yun-fu Gu;J. Gutknecht;B. Hungate;X. Le Roux;Xingyu Ma;A. Niboyet;T. Yuan;Jizhong Zhou;Yunfeng Yang
大气中二氧化碳浓度的不断增加极大地改变了生态系统的功能。然而，很少有研究探讨二氧化碳浓度升高对土壤微生物群落的长期（即十多年）影响。我们使用 16S rRNA 基因扩增子和 GeoChip 微阵列，研究了经过 14 年实验性升高的 CO2（比环境高 275 ppm）后加利福尼亚州一年生草地的土壤微生物群落。二氧化碳浓度升高改变了土壤微生物群落的分类和功能基因组成。在 CO2 升高的情况下，具有较高核糖体 RNA 操纵子 (rrn) 拷贝数的类群的相对丰度下降，这是一种对培养物中资源可用性做出积极反应的功能性状。相反，拷贝数较低的类群因二氧化碳浓度升高而增加。结果，显着变化的 OTU 的丰度加权平均拷贝数从环境 CO2 时的 2.27 下降到 CO2 升高时的 2.01。 CO2 浓度升高时，固氮 (N) 基因和氨氧化基因分别显着降低 12.6% 和 6.1%。与此同时，在 CO2 升高的情况下，硝化酶活性下降了 48.3%，尽管这种变化并不显着。土壤有效氮也出现了大幅但不显着的下降，硝酸盐 (NO3−) (−27.4%) 和铵 (NH4+) (−15.4%) 均下降。此外，大量与碳（C）降解相关的微生物基因也受到二氧化碳浓度升高的影响，而与碳固定相关的基因基本保持不变。长期CO2升高引起的微生物群落和土壤氮库的总体变化表明微生物氮分解受到限制，从而减缓了微生物群落的潜在最大生长速率。
The continuously increasing concentration of atmospheric CO2has considerably altered ecosystem functioning. However, few studies have examined the long-term (i.e. over a decade) effect of elevated CO2on soil microbial communities. Using16S rRNAgene amplicons and a GeoChip microarray, we investigated soil microbial communities from a Californian annual grassland after 14 years of experimentally elevated CO2(275 ppm higher than ambient). Both taxonomic and functional gene compositions of the soil microbial community were modified by elevated CO2. There was decrease in relative abundance for taxa with higher ribosomal RNA operon (rrn) copy number under elevated CO2, which is a functional trait that responds positively to resource availability in culture. In contrast, taxa with lowerrrncopy number were increased by elevated CO2. As a consequence, the abundance-weighted averagerrncopy number of significantly changed OTUs declined from 2.27 at ambient CO2to 2.01 at elevated CO2. The nitrogen (N) fixation genenifHand the ammonium-oxidizing geneamoAsignificantly decreased under elevated CO2by 12.6% and 6.1%, respectively. Concomitantly, nitrifying enzyme activity decreased by 48.3% under elevated CO2, albeit this change was not significant. There was also a substantial but insignificant decrease in available soil N, with both nitrate (NO3−) (−27.4%) and ammonium (NH4+) (−15.4%) declining. Further, a large number of microbial genes related to carbon (C) degradation were also affected by elevated CO2, whereas those related to C fixation remained largely unchanged. The overall changes in microbial communities and soil N pools induced by long-term elevated CO2suggest constrained microbial N decomposition, thereby slowing the potential maximum growth rate of the microbial community.