Low-Level Nitrogen Addition Promotes Net Methane Uptake in a Boreal Forest across the Great Xing' an Mountain Region, China
Low-Level Nitrogen Addition Promotes Net Methane Uptake in a Boreal Forest across the Great Xing' an Mountain Region, China
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DOI：
10.5849/forsci.13-075
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发表时间：
2014-10
期刊：
影响因子：
1.4
通讯作者：
Minjie Xu;S. Cheng;H. Fang;Guirui Yu;Wenlong Gao;Yongsheng Wang;X. Dang;Linsen Li
中科院分区：
文献类型：
--
作者：
Minjie Xu;S. Cheng;H. Fang;Guirui Yu;Wenlong Gao;Yongsheng Wang;X. Dang;Linsen Li
慢性氮 (N) 沉降可能会改变北方森林土壤中甲烷 (CH4) 吸收的数量和方向，但引起土壤 CH4 吸收变化的氮沉降临界水平仍然未知。在东北大兴安岭冷温带针叶林中，以对照（0 kg N ha(-1) 年(-1)）、低氮（10 kg N ha(-1) 年(-1)）、中氮（20 kg N ha' 年（-1））和高氮（40 kg N ha(-1) 年(-1)）四种比例添加 NH4NO3 肥料。测定土壤大气CH4通量以及土壤温度、土壤湿度、矿质氮、溶解有机碳（DOC）和pH值，探讨不同施氮水平下控制土壤CH4吸收通量的主要因素。我们的结果表明，施氮不会改变土壤温度、土壤湿度和土壤 NH4+-N 浓度。低氮而不是中氮和高氮显着增加了矿层中土壤 DOC 和 NO3--N 浓度以及土壤 CH4 吸收通量。此外，施肥的森林土壤出现土壤酸化，土壤pH值下降0.4个单位。寒温带森林土壤CH4吸收以土壤水分为主，其次是土壤DOC和土壤矿物质N。低氮似乎通过增加土壤DOC和NO3--N含量来刺激土壤CH4吸收。这些结果表明，低水平的氮添加（<20 kg N ha-1year(-1)）可以促进寒温带针叶林土壤中CH4的吸收，这也有利于北方森林的碳汇。
Chronic nitrogen (N) deposition may alter the amount and direction of methane (CH4) uptake in boreal forest soils, but the critical level of N deposition eliciting the alteration of soil CH4 uptake remains unknown. In a cold-temperate coniferous forest in the Great Xing' an Mountain of northeastern China, NH4NO3 fertilizer was added at four rates: control (0 kg N ha(-1) year(-1)), low N (10 kg N ha(-1) year(-1)), medium N (20 kg N ha' year(-1)), and high N (40 kg N ha(-1) year(-1)). Soil atmospheric CH4 fluxes as well as soil temperature, soil moisture, mineral N, dissolved organic carbon (DOC), and pH values were determined to explore the main factors controlling soil CH4 uptake fluxes under different N addition levels. Our results showed that N addition did not alter soil temperature, soil moisture, and soil NH4+-N concentrations. Low N rather than medium and high N significantly increased soil DOC and NO3--N concentrations in mineral horizon as well as soil CH4 uptake fluxes. In addition, soil acidification occurred in the fertilized forest soils, because soil pH declined by 0.4 unit. CH4 uptake in the cold-temperate forest soil was dominated by soil moisture followed by soil DOC and soil mineral N. Low N seemed to stimulate soil CH4 uptake through increasing the contents of soil DOC and NO3--N. These results suggest that low-level N addition (< 20 kg N ha-1 year(-1)) can promote CH4 uptake in the cold-temperate coniferous forest soil, which is also conducive to carbon sequestration of the boreal forests.