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	Are nitrate production and retention processes in subtropical acidic forest soils responsive to ammonium deposition?
	Gao W. L.; Kou, L.; Yang, H.; Zhang, J. B.; Muller, C.; Li, S. G.
	2016
关键词	N deposition Gross N transformations DNRA N-15 tracing model Acid soil of subtropical forest chilean nothofagus forest nitrogen deposition heterotrophic nitrification tropical forest terrestrial ecosystems oxide emissions pine plantation root decay n-15 china
英文摘要	Changes in soil N-cycling and retention processes in subtropical/tropical acidic forest ecosystems under anthropogenic N inputs are not well understood. We conducted a laboratory N-15 tracing study on an acid soil (pH values: 4.6 to 5.0) from a subtropical forest fertilized for more than 2.5 years at a rate of 0, 40, and 120 kg NH4Cl-N ha(-1) yr(-1), respectively. To get a better resolution of mechanistic changes in soil N cycling and retention processes under NHS additions, we used a conceptual N-15 tracing model to quantify process-specific and pool-specific N transformation rates in soils. Gross N mineralization rates decreased at high NH4+ additions, which were paralleled by a reduction in fungal biomass and mineralization of recalcitrant organic N. Gross NHS immobilization rates did not show a change with increasing NH4+ additions. Interestingly, soil NO3- production (heterotrophic, autotrophic, and gross nitrification) and retention (NO3- immobilization and dissimilatory nitrate reduction to ammonium) showed insensitivity to increasing additions of NH4+. The mechanisms behind the lack of response of heterotrophic nitrification were unclear, but possibly related to the absence of significant changes in soil C:N ratio and soil acidity under increased NH4+ additions. Because of the low autotrophic nitrification potential and the lack of NH4+ limitation to autotrophic nitrifiers, autotrophic nitrification was unresponsive to NH4+ additions. NO3- immobilization rates appeared to be controlled by the NO3- produced from heterotrophic nitrification, as indicated by the positive relationship between NO3- immobilization and heterotrophic nitrification (R-2 = 0.59, p = 0.015), thus showing a lack of a change under increased NH4+ additions. DNRA seemed to be inherently less responsive to environmental changes such as NH4+ deposition. Our work demonstrates that enhanced NH4+ deposition has a low potential to stimulate soil NO3- production and weaken soil retention of NO3- in this, and perhaps other subtropical/tropical acidic forest ecosystems. (C) 2016 Elsevier Ltd. All rights reserved.
出处	Soil Biology & Biochemistry
卷	100
页	102-109
语种	英语
ISSN号	0038-0717
DOI标识	10.1016/j.soilbio.2016.06.002
内容类型	SCI/SSCI论文
源URL	[http://ir.igsnrr.ac.cn/handle/311030/42945]
专题	地理科学与资源研究所_历年回溯文献
推荐引用方式 GB/T 7714	Gao W. L.,Kou, L.,Yang, H.,et al. Are nitrate production and retention processes in subtropical acidic forest soils responsive to ammonium deposition?. 2016.

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