Song Wenchen, Tong Xiaojuan, Liu Yanhong, Li Weike
College of Forestry, Beijing Forestry University, Beijing, China.
Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
Front Microbiol. 2020 Feb 27;11:314. doi: 10.3389/fmicb.2020.00314. eCollection 2020.
Rhizosphere microbes in forests are key elements of the carbon sequestration of terrestrial ecosystems. To date, little is known about how the diversity and species interactions of the active rhizomicrobial community change during soil carbon sequestration and what interactions drive these changes. In this study, we used a combination of DNA and stable isotope method to explore correlations between the composition of microbial communities, N transformation, and the sequestration of carbon in soils around and roots in North China. Rhizosphere soils from degraded lands, primary stage land (tree roots had colonized in degraded soil for 1 year), and nature forest were sampled for analyses. The results showed that microbial communities and newly sequestered soil organic carbon (SOC) contents changed with different tree species, environments, and successive stages. The fungal unweighted and weighted UniFrac distances could better show the different microbial species structures and differences in successive stages. Newly sequestered SOC was positively correlated with the bacterial order (in forests), the fungal order Russulales (in forests), and δN. Consequently, the bacterial order acted as an important taxa for root-driven carbon sequestration, and the fungal order Russulales acted as an important taxa for root-driven carbon sequestration. The two plant species allocated root exudates to different portion of their root systems, which in turn altered microbial community composition and function. The δN of soil organic matter could be an important indicator to estimate root-driven carbon sequestration.
森林中的根际微生物是陆地生态系统碳固存的关键要素。迄今为止，关于活跃的根际微生物群落的多样性和物种相互作用在土壤碳固存过程中如何变化以及哪些相互作用驱动了这些变化，人们了解甚少。在本研究中，我们结合DNA和稳定同位素方法，探究了华北地区根际及根系周围土壤中微生物群落组成、氮转化与碳固存之间的相关性。采集了退化土地、初级阶段土地（树木根系在退化土壤中已定植1年）和天然林的根际土壤进行分析。结果表明，微生物群落和新固存的土壤有机碳（SOC）含量随不同树种、环境和演替阶段而变化。真菌的非加权和加权UniFrac距离能更好地显示不同的微生物物种结构以及演替阶段的差异。新固存的SOC与细菌目（在森林中）、红菇目真菌（在森林中）和δN呈正相关。因此，细菌目是根系驱动碳固存的重要分类群，红菇目真菌是根系驱动碳固存的重要分类群。两种植物物种将根系分泌物分配到其根系的不同部位，这反过来又改变了微生物群落的组成和功能。土壤有机质的δN可能是估计根系驱动碳固存的一个重要指标。
