Yang Xuemei, Ma Suhui, Huang Erhan, Zhang Danhua, Chen Guoping, Zhu Jiangling, Ji Chengjun, Zhu Biao, Liu Lingli, Fang Jingyun
Institute of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, 100871, China.
Ministry of Education Key Laboratory for Transboundary Ecosecurity of Southwest China, School of Ecology and Environmental Science, Yunnan University, Kunming, 650500, China.
Sci China Life Sci. 2025 Jan;68(1):284-293. doi: 10.1007/s11427-024-2752-2. Epub 2024 Oct 25.
Soil is the largest carbon (C) reservoir in terrestrial ecosystems and plays a crucial role in regulating the global C cycle and climate change. Increasing nitrogen (N) deposition has been widely considered as a critical factor affecting soil organic carbon (SOC) storage, but its effect on SOC components with different stability remains unclear. Here, we analyzed extensive empirical data from 304 sites worldwide to investigate how SOC and its components respond to N addition. Our analysis showed that N addition led to a significant increase in bulk SOC (6.7%), with greater increases in croplands (10.6%) and forests (6.0%) compared to grasslands (2.1%). Regarding SOC components, N addition promoted the accumulation of plant-derived C (9.7%-28.5%) over microbial-derived C (0.2%), as well as labile (5.7%) over recalcitrant components (-1.2%), resulting in a shift towards increased accumulation of plant-derived labile C. Consistently, N addition led to a greater increase in particulate organic C (11.9%) than mineral-associated organic C (3.6%), suggesting that N addition promotes C accumulation across all pools, with more increase in unstable than stable pools. The responses of SOC and its components were best predicted by the N addition rate and net primary productivity. Overall, our findings suggest that N enrichment could promote the accumulation of plant-derived and non-mineral associated C and a subsequent decrease in the overall stability of soil C pool, which underscores the importance of considering the effects of N enrichment on SOC components for a better understanding of C dynamics in soils.
土壤是陆地生态系统中最大的碳（C）库，在调节全球碳循环和气候变化方面发挥着关键作用。增加氮（N）沉降已被广泛认为是影响土壤有机碳（SOC）储存的一个关键因素，但其对不同稳定性的SOC组分的影响仍不清楚。在此，我们分析了来自全球304个站点的大量实证数据，以研究SOC及其组分如何响应氮添加。我们的分析表明，氮添加导致土壤总有机碳显著增加（6.7%），与草地（2.1%）相比，农田（10.6%）和森林（6.0%）的增加幅度更大。关于SOC组分，氮添加促进了植物源碳（9.7%-28.5%）相对于微生物源碳（0.2%）的积累，以及活性组分（5.7%）相对于难分解组分（-1.2%）的积累，导致向植物源活性碳积累增加的方向转变。一致地，氮添加导致颗粒有机碳的增加幅度（11.9%）大于矿物结合有机碳（3.6%），这表明氮添加促进了所有碳库的碳积累，不稳定碳库的增加幅度大于稳定碳库。SOC及其组分的响应最好由氮添加速率和净初级生产力预测。总体而言，我们的研究结果表明，氮富集可以促进植物源和非矿物结合碳的积累，以及随后土壤碳库整体稳定性的降低，这强调了考虑氮富集对SOC组分的影响对于更好地理解土壤碳动态的重要性。
