State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing 100084, China; Key Laboratory of Stable Isotope and Gulf Ecology, Institute of Ocean Engineering, Tsinghua Shenzhen International Graduate School, Shenzhen 518055, China.
Sci Total Environ. 2022 Dec 1;850:157992. doi: 10.1016/j.scitotenv.2022.157992. Epub 2022 Aug 13.
The mangrove ecosystem is an important CO sink with an extraordinarily high primary productivity. However, it is vulnerable to the impact of climate warming and eutrophication. While there has been extensive research on plant growth and greenhouse gas emission in mangrove ecosystems, microbial communities, the primary biogeochemical cycling drivers, are much less understood. Here, we examined whether short-term experimental treatments: (1) eutrophication with a supplement of 185 g N m·year (N), (2) 3°C warming (W), and (3) the dual treatment of N and W (NW) were sufficient to alter microbial communities in the sediment. After 4 months of experiments, most environmental factors remained unchanged. However, N had significant, strong effects on bacterial, fungal, and functional community compositions, while the effects of W on microbial communities were weaker. N increased bacterial richness, phylogenetic diversity, and evenness, owing to stronger stochastic processes induced by eutrophication. There were no interactive effects of N and W on bacterial, fungal, and functional community compositions, suggesting that joint effects of N and W were additive. Concomitant with higher NO efflux induced by N, the relative abundances of most bacterial nitrogen cycling genes were increased or remained changed by N. In contrast, N decreased or did not change those of most bacterial carbon degradation genes, while W increased or did not change the relative abundances of most of bacterial and fungal carbon degradation genes, implying higher carbon degradation potentials. As the most abundant inorganic nitrogenous species in mangrove sediment, ammonium was a key factor in shaping microbial functional communities. Collectively, our findings showed that microbial community compositions in the mangrove sediment were highly sensitive to short-term N and W treatments, giving rise to ecological consequences such as higher NO efflux.
红树林生态系统是一个重要的 CO2 汇，具有极高的初级生产力。然而，它易受气候变暖与富营养化的影响。尽管已经有大量关于红树林生态系统中植物生长和温室气体排放的研究，但微生物群落这一主要的生物地球化学循环驱动因素，仍知之甚少。在这里，我们研究了短期实验处理（1）添加 185 g N m·年的富营养化（N），（2）升温 3°C（W），和（3）N 和 W 的双重处理（NW）是否足以改变沉积物中的微生物群落。经过 4 个月的实验，大多数环境因素保持不变。然而，N 对细菌、真菌和功能群落组成有显著而强烈的影响，而 W 对微生物群落的影响较弱。N 增加了细菌的丰富度、系统发育多样性和均匀度，这归因于富营养化引起的更强的随机过程。N 和 W 对细菌、真菌和功能群落组成没有交互作用，表明 N 和 W 的联合效应是相加的。伴随着 N 引起的更高的 NO 外排，大多数细菌氮循环基因的相对丰度增加或保持不变。相反，N 减少或没有改变大多数细菌碳降解基因的相对丰度，而 W 增加或没有改变大多数细菌和真菌碳降解基因的相对丰度，这意味着更高的碳降解潜力。作为红树林沉积物中最丰富的无机含氮物种，铵是塑造微生物功能群落的关键因素。总的来说，我们的研究结果表明，红树林沉积物中的微生物群落组成对短期的 N 和 W 处理非常敏感，导致了更高的 NO 外排等生态后果。
