环境科学
生态系统
热带
自行车
温带气候
陆地生态系统
沉积(地质)
土壤碳
生物地球化学
固碳
氮气循环
温带雨林
全球变化
氮气
土壤水分
土壤有机质
气候变化
土壤科学
生态学
环境化学
化学
林业
生物
地理
二氧化碳
古生物学
有机化学
沉积物
作者
Xiankai Lu,Peter M. Vitousek,Qigui Mao,Frank S. Gilliam,Yiqi Luo,Benjamín L. Turner,Guoyi Zhou,Jiangming Mo
标识
DOI:10.1073/pnas.2020790118
摘要
Terrestrial ecosystem carbon (C) sequestration plays an important role in ameliorating global climate change. While tropical forests exert a disproportionately large influence on global C cycling, there remains an open question on changes in below-ground soil C stocks with global increases in nitrogen (N) deposition, because N supply often does not constrain the growth of tropical forests. We quantified soil C sequestration through more than a decade of continuous N addition experiment in an N-rich primary tropical forest. Results showed that long-term N additions increased soil C stocks by 7 to 21%, mainly arising from decreased C output fluxes and physical protection mechanisms without changes in the chemical composition of organic matter. A meta-analysis further verified that soil C sequestration induced by excess N inputs is a general phenomenon in tropical forests. Notably, soil N sequestration can keep pace with soil C, based on consistent C/N ratios under N additions. These findings provide empirical evidence that below-ground C sequestration can be stimulated in mature tropical forests under excess N deposition, which has important implications for predicting future terrestrial sinks for both elevated anthropogenic CO2 and N deposition. We further developed a conceptual model hypothesis depicting how soil C sequestration happens under chronic N deposition in N-limited and N-rich ecosystems, suggesting a direction to incorporate N deposition and N cycling into terrestrial C cycle models to improve the predictability on C sink strength as enhanced N deposition spreads from temperate into tropical systems.
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