Soil carbon availability decouples net nitrogen mineralization and net nitrification across United States Long Term Ecological Research sites
Soil carbon availability decouples net nitrogen mineralization and net nitrification across United States Long Term Ecological Research sites
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DOI：
10.1007/s10533-022-01011-w
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发表时间：
2023-01
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影响因子：
4
通讯作者：
A. L. Gill;R. M. Grinder;C. See;F. Chapin;L. C. DeLancey;M. C. Fisk;P. Groffman;T. Harms;S. Hobbie;J. Knoepp;J. H. Knops;M. Mack;P. Reich;A. D. Keiser
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作者：
A. L. Gill;R. M. Grinder;C. See;F. Chapin;L. C. DeLancey;M. C. Fisk;P. Groffman;T. Harms;S. Hobbie;J. Knoepp;J. H. Knops;M. Mack;P. Reich;A. D. Keiser
自养和异养生物需要碳(C)与营养物质化学计量平衡比例的资源，对碳(C)与营养物质的需求联系着有机体和生态系统层面的生物地球化学循环。在土壤中，C和N的相对有效性也决定了自养硝化菌和异养分解者对铵的竞争强度，这可能影响氮矿化和硝化之间的耦合动态。本研究利用美国国家科学基金会资助的长期生态研究（LTER）网络的公开数据，评估了土壤C浓度对净硝化和净氮矿化之间关系的影响。我们发现，土壤C有效性限制了最终在整个大陆梯度上被硝化的矿化N的比例，这有助于降低高C浓度土壤的硝化率。硝化作用产生的硝酸盐是一种高流动性离子，很容易渗入水生生态系统或反硝化成温室气体一氧化二氮（N2O）。因此，了解土壤C浓度与土壤N转化之间的联系对于管理潜在的生态系统N损失，理解这些损失的生物地球化学约束，以及在生态系统模型中准确地表示耦合的C-N动态具有重要意义。
Autotrophic and heterotrophic organisms require resources in stoichiometrically balanced ratios of carbon (C) to nutrients, the demand for which links organismal and ecosystem-level biogeochemical cycles. In soils, the relative availability of C and nitrogen (N) also defines the strength of competition for ammonium between autotrophic nitrifiers and heterotrophic decomposers, which may influence the coupled dynamics between N mineralization and nitrification. Here, we use data from the publicly available US National Science Foundation funded Long Term Ecological Research (LTER) network to evaluate the influence of soil C concentration on the relationship between net nitrification and net N mineralization. We found that soil C availability constrains the fraction of mineralized N that is ultimately nitrified across the continental gradient, contributing to reduced rates of nitrification in soils with high C concentrations. Nitrate, which is produced by nitrification, is a highly mobile ion that easily leaches to aquatic ecosystems or denitrifies into the greenhouse gas nitrous oxide (N2O). Understanding the connection between soil C concentration and soil N transformations is thus important for managing potential ecosystem N losses, understanding the biogeochemical constraints of these losses, and accurately representing coupled C-N dynamics in ecosystem models.