Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branišovská 31, 370 05, České Budějovice, Czech Republic.
Czech Geological Survey, Department of Environmental Geochemistry and Biogeochemistry, Prague, 118 21, Czech Republic.
Sci Rep. 2017 Aug 29;7(1):9738. doi: 10.1038/s41598-017-08554-1.
Nitrogen leaching owing to elevated acid deposition remains the main ecosystem threat worldwide. We aimed to contribute to the understanding of the highly variable nitrate losses observed in Europe after acid deposition retreat. Our study proceeded in adjacent beech and spruce forests undergoing acidification recovery and differing in nitrate leaching. We reconstructed soil microbial functional characteristics connected with nitrogen and carbon cycling based on community composition. Our results showed that in the more acidic spruce soil with high carbon content, where Acidobacteria and Actinobacteria were abundant (Proteo:Acido = 1.3), the potential for nitrate reduction and loss via denitrification was high (denitrification: dissimilative nitrogen reduction to ammonium (DNRA) = 3). In the less acidic beech stand with low carbon content, but high nitrogen availability, Proteobacteria were more abundant (Proteo:Acido = 1.6). Proportionally less nitrate could be denitrified there (denitrification:DNRA = 1), possibly increasing its availability. Among 10 potential keystone species, microbes capable of DNRA were identified in the beech soil while instead denitrifiers dominated in the spruce soil. In spite of the former acid deposition impact, distinct microbial functional guilds developed under different vegetational dominance, resulting in different N immobilization potentials, possibly influencing the ecosystem's nitrogen retention ability.
由于酸沉降增加导致的氮淋失仍然是全世界主要的生态系统威胁。我们旨在深入了解欧洲在酸沉降减少后观察到的高度可变的硝酸盐损失。我们的研究在经历酸化恢复的相邻山毛榉林和云杉林中进行，这些森林在硝酸盐淋失方面存在差异。我们基于群落组成重建了与氮和碳循环有关的土壤微生物功能特征。我们的研究结果表明，在酸性更强、碳含量更高的云杉土壤中，那里富含 Acidobacteria 和 Actinobacteria（Proteo:Acido=1.3），硝酸盐还原和通过反硝化作用损失的潜力很大（反硝化作用：异化氮还原为铵（DNRA）=3）。在酸性较弱、碳含量较低但氮素供应较高的山毛榉林中，Proteobacteria 更为丰富（Proteo:Acido=1.6）。那里可能有更少的硝酸盐可以被反硝化（反硝化作用：DNRA=1），从而可能增加其可用性。在 10 个潜在的关键种中，在山毛榉土壤中鉴定出了能够进行 DNRA 的微生物，而在云杉土壤中则以反硝化菌为主。尽管存在先前的酸沉降影响，但不同的植被优势下形成了不同的微生物功能群，导致不同的氮固定潜力，这可能影响生态系统的氮保留能力。
