Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, Xianlin Avenue 163, Nanjing 210093, China.
International Institute for Earth System Science, Nanjing University, Xianlin Avenue 163, Nanjing 210093, China.
Sci Rep. 2016 Dec 14;6:39173. doi: 10.1038/srep39173.
Over the past 100 years, human activity has greatly changed the rate of atmospheric N (nitrogen) deposition in terrestrial ecosystems, resulting in N saturation in some regions of the world. The contribution of N saturation to the global carbon budget remains uncertain due to the complicated nature of C-N (carbon-nitrogen) interactions and diverse geography. Although N deposition is included in most terrestrial ecosystem models, the effect of N saturation is frequently overlooked. In this study, the IBIS (Integrated BIosphere Simulator) was used to simulate the global-scale effects of N saturation during the period 1961-2009. The results of this model indicate that N saturation reduced global NPP (Net Primary Productivity) and NEP (Net Ecosystem Productivity) by 0.26 and 0.03 Pg C yr, respectively. The negative effects of N saturation on carbon sequestration occurred primarily in temperate forests and grasslands. In response to elevated CO levels, global N turnover slowed due to increased biomass growth, resulting in a decline in soil mineral N. These changes in N cycling reduced the impact of N saturation on the global carbon budget. However, elevated N deposition in certain regions may further alter N saturation and C-N coupling.
在过去的 100 年中，人类活动极大地改变了陆地生态系统大气氮（N）沉积的速率，导致世界上一些地区出现氮饱和。由于 C-N（碳-氮）相互作用的复杂性和地理环境的多样性，氮饱和对全球碳预算的贡献仍然不确定。尽管氮沉积被纳入大多数陆地生态系统模型中，但氮饱和的影响经常被忽视。在这项研究中，使用综合生物地球模拟器（IBIS）来模拟 1961 年至 2009 年期间全球范围内氮饱和的影响。该模型的结果表明，氮饱和使全球净初级生产力（NPP）和净生态系统生产力（NEP）分别减少了 0.26 和 0.03 Pg C yr。氮饱和对碳封存的负面影响主要发生在温带森林和草原。由于生物量的增长，大气 CO 水平升高导致全球氮周转减缓，从而导致土壤矿质氮减少。氮循环的这些变化降低了氮饱和对全球碳预算的影响。然而，某些地区氮沉积的增加可能会进一步改变氮饱和和 C-N 耦合。
