土壤微生物群落动态调节了新鲜植物残体原位分解引起的激发效应。

Soil microbial community dynamics mediate the priming effects caused by in situ decomposition of fresh plant residues.

机构信息

Research Institute of Tropical Forestry, Chinese Academy of Forestry, Longdong, Guangzhou 510520, PR China.

出版信息

Sci Total Environ. 2020 Oct 1;737:139708. doi: 10.1016/j.scitotenv.2020.139708. Epub 2020 May 27.

DOI:10.1016/j.scitotenv.2020.139708

Abstract

Extreme climate events always leave numerous fresh plant materials (FOM) in forests, thus increasing the input of carbon (C) resources to soil system. The input of exogenous C may accelerate or inhibit the decomposition of soil organic carbon (SOC), which is defined as the positive or negative priming effect (PE), respectively. However, the characteristics and microbial mechanisms of PE caused by FOM remain unknown. A 110-day in situ soil incubation experiment was conducted in a subtropical forest, with C-labeled fresh leaves from four native species (Castanopsis fissa, CF; Pinus massoniana, PM; Machilus chekiangensis, MC; and Castanopsis chinensis, CC) serving as the FOM respectively. We measured the CO effluxes derived from C-labeled FOM and soil, and the composition and diversity of soil bacterial and fungal communities throughout the incubation to explore the correlations between PE and microbial attributes. As a result, the PE caused by FOM inputs were negative initially but became positive after 61 d. The FOM decomposition rate was positively related to PE intensity, and there was a significant difference between coniferous and broadleaved species in the middle period of the study. More than 77% of the total C lost from FOM was emitted as CO, indicating that FOM-C serves as an energy resource for soil microbes. The α-diversity of the bacterial community at genus-level showed significantly positive correlation with PE at 24 d, and the composition of bacterial community at OTU-level had a marked relationship with the PE between 24-110 d. The relationship between fungal community diversity and composition with PE was only observed at 7 and 110 d, respectively. This study firstly investigated the patterns of PE resulted from numerous FOM input, and the results suggested that soil bacterial community, in particular the Actinobacteria phyla, played a more important role in triggering such PEs than fungal community.

摘要

极端气候事件总会在森林中留下大量的新鲜植物材料（FOM），从而增加了碳（C）资源向土壤系统的输入。外源性 C 的输入可能会加速或抑制土壤有机碳（SOC）的分解，这分别被定义为正或负激发效应（PE）。然而，FOM 引起的 PE 的特征和微生物机制尚不清楚。在亚热带森林中进行了一项为期 110 天的原位土壤培养实验，分别使用四种本地物种（锥栗、马尾松、浙江楠和栲树）的 C 标记新鲜叶片作为 FOM。我们测量了源自 C 标记 FOM 和土壤的 CO 通量，以及整个培养过程中土壤细菌和真菌群落的组成和多样性，以探究 PE 与微生物特性之间的相关性。结果表明，FOM 输入引起的 PE 最初为负，但在 61d 后变为正。FOM 分解率与 PE 强度呈正相关，在研究中期，针叶树种和阔叶树种之间存在显著差异。FOM 中超过 77%的 C 损失以 CO 的形式排放，表明 FOM-C 是土壤微生物的能量来源。属水平的细菌群落的 α 多样性与 24d 的 PE 呈显著正相关，而 OTU 水平的细菌群落组成与 24-110d 的 PE 之间存在显著关系。真菌群落多样性和组成与 PE 的关系仅分别在 7d 和 110d 时观察到。本研究首次调查了大量 FOM 输入引起的 PE 模式，结果表明，土壤细菌群落，特别是放线菌门，在引发这种 PE 方面比真菌群落发挥了更重要的作用。