水热条件变化对黑土细菌群落结构的影响及其演替特征

Adaptive patterns of bacterial communities under increased temperature and precipitation associated with soil displacement

摘要:

全球气候变化导致的水热条件变化，对土壤微生物群落结构及功能产生重要影响。深入理解这些变化如何影响微生物群落的结构及其随时间的演替，对于有效预测和适应未来的气候变化至关重要。【目的】在气候变化背景下，本研究旨在探索黑土细菌群落的多样性、组成和结构，以及群落演替特征的变化情况。【方法】利用中国科学院海伦、封丘、鹰潭农田生态系统国家野外科学观测研究站长期土壤置换实验平台，选择寒温带地区(中国海伦)的黑土作为研究对象，并将其移置于暖温带地区(封丘)和中亚热带地区(鹰潭)以模拟水热条件增加。通过采集2005年至2011年的63个黑土样本(包括原位、移置封丘县和移置鹰潭市)，利用16S rRNA基因高通量测序技术，研究了水热条件变化对黑土细菌群落多样性、组成和结构的影响；同时结合土壤理化性质，分析环境因素与微生物群落特征间的关系，并计算物种周转率(w)。【结果】经过6年的移置，将寒温带黑土移至暖温带和中亚热带后，土壤的理化性质发生了显著改变。土壤有机质和全氮含量显著降低，地上部生物量显著减少。土壤细菌群落的多样性下降，群落组成和结构发生了显著变化。主要细菌类群包括疣微菌门(Verrucomicrobia)、变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)和放线菌门(Actinobacteria)等，其中疣微菌门在移置鹰潭地区后的相对丰度显著增加。此外，气候因子与微生物群落特征高度相关。非度量多维尺度分析显示，群落结构随水热条件和时间的变化而演替，这与微生物时间周转率的增加相关。在不同水热条件下，细菌群落的时间周转率差异显著，依次为0.030 (海伦)<0.033 (封丘)<0.045 (鹰潭)。【结论】6年的水热条件增加显著降低了细菌群落的多样性，显著改变了其组成和结构，并加快了细菌群落时间周转率的响应。

Abstract:

The temperature and precipitation variations caused by global climate change have profoundly impacted soil microbial communities. Understanding the impacts of the variations on the structure and function of microbial communities over time is crucial for predicting and adapting to future climate changes. [Objective] To explore the variations in the diversity, composition, structure, and succession of bacterial communities in mollisol soil in the context of climate change. [Methods] Based on a long-term soil transplantation experiment platform of Hailun, Fengqiu and Yingtan Agroecosystem Field Experiment Stations of the Chinese Academy of Sciences, we translocated the mollisol soil from a cold-temperate region (Hailun) to a warm-temperate region (Fengqiu) and a mid-subtropical region (Yingtan) to simulate the increasing conditions of temperature and precipitation. We collected 63 mollisol soil samples from Hailun, Fengqiu, and Yingtan during 2005–2011. We employed high-throughput sequencing of the 16S rRNA gene to study the diversity, composition, and structure of soil bacterial communities under different temperature and precipitation conditions. With consideration to the soil physicochemical properties, we analyzed the relationship between environmental factors and microbial community characteristics and calculated the species turnover rate. [Results] After six years of transplantation of the mollisol soil from the cold temperate zone to warm temperate and mid-subtropical zones, significant changes occurred in soil physicochemical properties, including decreases in soil organic matter and total nitrogen, along with a noticeable reduction in aboveground biomass. Moreover, the bacterial diversity in the soil decreased, and significant changes occurred in the community composition and structure. The dominant bacteria included Verrucomicrobia, Proteobacteria, Acidobacteria, and Actinobacteria, among which Verrucomicrobia showed increased relative abundance after the soil transplantation to the warmer area Yingtan. Additionally, climatic factors were highly correlated with microbial community characteristics. The nonmetric multidimensional scaling analysis showed that the bacterial community structure evolved with changes in temperature and precipitation and over time, which was related to the increased microbial species turnover rate. The species turnover rates of bacterial communities varied significantly under different temperature and precipitation conditions, following an increasing trend of Hailun (0.030)[Conclusion] A six-year increase in temperature and precipitation significantly reduced the bacterial diversity, altered the bacterial community composition and structure, and accelerated the species turnover.