Key Laboratory of Humid Subtropical Eco-Geographical Process, Ministry of Education, Fujian Normal University, Fuzhou 350007, China.
School of Environment and Resource, Fuzhou University, Fuzhou 350116, China.
FEMS Microbiol Ecol. 2019 Sep 1;95(9). doi: 10.1093/femsec/fiz120.
Despite the growing recognition regarding the carbon cycle in the rhizosphere of upland ecosystems, little is known regarding the rhizosphere effect on soil organic carbon (SOC) mineralization in tidal marsh soils. In the current study, in situ rhizobox experiments (including rhizosphere and inner and outer bulk soil) were conducted in an estuarine tidal marsh. Our results showed that a higher abundance of total bacteria, Geobacter, dsrA and mcrA and lower α-diversity were observed in the rhizosphere relative to the bulk soil. Rhizosphere effects shifted the partition of terminal metabolic pathways from sulfate reduction in the bulk soil to the co-dominance of microbial Fe(III) and sulfate reduction in the rhizosphere. Although the rhizosphere effect promoted the rates of three terminal metabolic pathways, it showed greater preference towards microbial Fe(III) reduction in the tidal marsh soils. Plant species had little impact on the partitioning of terminal metabolic pathways, but did affect the potential of total SOC mineralization together with the abundance and diversity of total bacteria. Both the rhizosphere effect and plant species influenced the bacterial community composition in the tidal marsh soils; however, plant species had a less pronounced impact on the bacterial community compared with that of the rhizosphere effect.
尽管人们越来越认识到旱地生态系统根际的碳循环，但对于潮汐沼泽土壤中根际对土壤有机碳（SOC）矿化的影响却知之甚少。在本研究中，在河口潮汐沼泽中进行了原位根盒实验（包括根际和内、外部分体土壤）。结果表明，与分体土壤相比，根际的总细菌、地杆菌、dsrA 和 mcrA 丰度更高，α多样性更低。根际效应改变了末端代谢途径的分配，从分体土壤中的硫酸盐还原转变为根际中微生物 Fe（III）和硫酸盐还原的共同优势。尽管根际效应促进了三个末端代谢途径的速率，但它在潮汐沼泽土壤中对微生物 Fe（III）还原表现出更大的偏好。植物种类对末端代谢途径的分配影响不大，但与总 SOC 矿化潜力以及总细菌的丰度和多样性一起影响总 SOC 矿化潜力。根际效应和植物种类都影响了潮汐沼泽土壤中的细菌群落组成；然而，与根际效应相比，植物种类对细菌群落的影响较小。
