Decrease of nitrogen cycle gene abundance and promotion of soil microbial-N saturation restrain increases in N2O emissions in a temperate forest with long-term nitrogen addition.
Decrease of nitrogen cycle gene abundance and promotion of soil microbial-N saturation restrain increases in N2O emissions in a temperate forest with long-term nitrogen addition.
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DOI：
10.1016/j.chemosphere.2023.139378
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发表时间：
2023-07
期刊：
影响因子：
8.8
通讯作者：
Shuaishuai Shang;Minghua Song;Chunmei Wang;Xiaomin Dou;Jiaxin Wang;Fangfang Liu;Chenying Zhu
中科院分区：
文献类型：
--
作者：
Shuaishuai Shang;Minghua Song;Chunmei Wang;Xiaomin Dou;Jiaxin Wang;Fangfang Liu;Chenying Zhu
土壤有效氮（N）的增加影响了N循环基因丰度和氧化亚氮（N2 O）的排放，这主要是由于N诱导的森林土壤酸化。土壤微生物氮饱和度的高低对土壤微生物活性和N2 O排放有一定的控制作用。氮诱导的微生物氮饱和度和氮循环基因丰度的变化对N2 O排放的贡献很少被量化。在这里，氮添加下N2 O排放的机制（氮的三种化学形式，即，NO3−-N、NH 4 +-N和NH 4 NO3-N，并分别以50和150 kg N ha− 1 year −1的两种施用量，于2011-2021年在北京温带森林中进行了调查。结果表明，在整个试验过程中，无论是低氮还是高氮处理，N2 O的排放量均高于对照。但近3年来，高NH_4NO_3-N和NH_4 ~+-N处理的N_2O排放量均低于相应的低N处理。氮素对微生物氮饱和度和氮循环基因丰度的影响与施氮量、施氮形式和施氮时间有关。具体而言，氮对氮循环基因丰度的负面影响和氮对微生物氮饱和度的正面影响在高氮量处理中得到证实，特别是在2019-2021年期间添加NH 4+。这些影响与土壤酸化有关。土壤微生物氮饱和度与N2 O排放量之间呈驼峰状变化趋势，表明土壤N2 O排放量随着土壤微生物氮饱和度的增加而减少。此外，氮诱导的N-循环基因丰度的减少抑制N2 O排放。特别是，硝化过程中，占主导地位的氨氧化古菌，是至关重要的，以确定N2 O的排放量在响应于N添加在温带森林。研究表明，施氮促进了土壤微生物氮饱和度的提高，降低了氮循环基因丰度，抑制了N2 O排放的持续增加。这对于理解气候变化下的森林-氮-微生物关系具有重要意义。
Increases in soil available nitrogen (N) influence N-cycle gene abundances and emission of nitrous oxide (N2O), which is primarily due to N-induced soil acidification in forest. Moreover, the extent of microbial-N saturation could control microbial activity and N2O emission. The contributions of N-induced alterations of microbial-N saturation and N-cycle gene abundances to N2O emission have rarely been quantified. Here, the mechanism underlying N2O emission under N additions (three chemical forms of N, i.e., NO3−-N, NH4+-N and NH4NO3–N, and each at two rates, 50 and 150 kg N ha−1year−1, respectively) spanning 2011–2021 was investigated in a temperate forest in Beijing. Results showed N2O emissions increased at both low and high N rates of all the three forms compared with control during the whole experiment. However, N2O emissions were lower in high rate of NH4NO3–N and NH4+-N treatments than the corresponding low N rates in the recent three years. Effects of N on microbial-N saturation and abundances of N-cycle genes were dependent on the N rate and form as well as experimental time. Specifically, negative effects of N on N-cycle gene abundances and positive effects of N on microbial-N saturation were demonstrated in high N rate treatments, particularly with NH4+addition during 2019–2021. Such effects were associated with soil acidification. A hump-backed trend between microbial-N saturation and N2O emissions was observed, suggesting N2O emissions decreased with increase of the microbial-N saturation. Furthermore, N-induced decreases in N-cycle gene abundances restrained N2O emissions. In particular, the nitrification process, dominated by ammonia-oxidize archaea, is critical to determination of N2O emissions in response to the N addition in the temperate forest. We confirmed N addition promoted soil microbial-N saturation and reduced N-cycle gene abundances, which restrained the continuous increase in N2O emissions. It is important for understanding the forest-N-microbe nexus under climate change.