Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Key Laboratory of Forest Ecology and Environment, State Forestry Administration, Beijing 100091, China.
Center for Conservation Biology, University of California, Riverside, Riverside, CA 92521, USA.
Sci Total Environ. 2019 Aug 10;677:272-280. doi: 10.1016/j.scitotenv.2019.04.310. Epub 2019 Apr 24.
Although many studies have reported the negative effects of elevated O on plant physiological characteristics, the influence of elevated O on below-ground processes and soil microbial functioning is less studied. In this study, we examined the effects of elevated O on soil properties, soil microbial biomass, as well as microbial community composition using high-throughput sequencing. Throughout one growing season, one-year old seedlings of two important endemic trees in subtropical China: Taxus chinensis (Pilger) Rehd. var. chinensis, and Machilus ichangensis Rehd. Et Wils, were exposed to charcoal-filtered air (CF as control), 100 nl l (E100) or 150 nl l (E150) O-enriched air, in open top chambers (OTCs). We found that only higher O exposure (E150) significantly decreased soil microbial biomass carbon and nitrogen in M. ichangensis, and the contents of organic matter were significantly decreased by E150 in both tree species. Although both levels of O exposure decreased NO-N in T. chinensis, only E150 increased NO-N in M. ichangensis, and there were no effects of O on NH-N. Moreover, elevated O elicited changes in soil microbial community structure and decreased fungal diversity in both M. ichangensis and T. chinensis. However, even though O exposure reduced bacterial diversity in M. ichangensis, no effect of O exposure on bacterial diversity was detected in soil grown with T. chinensis. Our results showed that elevated O altered the abundance of bacteria and fungi in general, and in particular reduced nitrifiers and increased the relative abundance of some fungal taxa capable of denitrification, which may stimulate NO emissions. Overall, our findings indicate that elevated O not only impacts the soil microbial community structure, but may also exert an influence on the functioning of microbial communities.
尽管许多研究报告了 O 升高对植物生理特性的负面影响，但 O 升高对地下过程和土壤微生物功能的影响研究较少。在这项研究中，我们使用高通量测序研究了 O 升高对土壤性质、土壤微生物生物量以及微生物群落组成的影响。在一个生长季节中，两种中国亚热带重要特有树种的一年生幼苗 Taxus chinensis（Pilger）Rehd. var. chinensis 和 Machilus ichangensis Rehd. Et Wils 被暴露在木炭过滤空气（CF 作为对照）、100 nl l（E100）或 150 nl l（E150）富 O 空气中，在开顶箱（OTC）中。我们发现，只有更高的 O 暴露（E150）显著降低了 M. ichangensis 土壤微生物生物量碳和氮，并且两种树种的有机质含量都显著降低了 E150。虽然两种 O 暴露水平都降低了 T. chinensis 的 NO-N，但只有 E150 增加了 M. ichangensis 的 NO-N，而 O 对 NH-N 没有影响。此外，O 升高改变了土壤微生物群落结构，降低了两种树种的真菌多样性。然而，尽管 O 暴露降低了 M. ichangensis 中的细菌多样性，但在 T. chinensis 生长的土壤中，O 暴露对细菌多样性没有影响。我们的结果表明，O 升高一般改变了细菌和真菌的丰度，特别是减少了硝化细菌，增加了一些具有反硝化能力的真菌类群的相对丰度，这可能会刺激 NO 排放。总体而言，我们的研究结果表明，O 升高不仅影响土壤微生物群落结构，还可能对微生物群落的功能产生影响。
