近日，浙江大学罗忠奎团队发现植物生产力的提高加剧了变暖下通过氮肥开采造成的底土碳损失。2025年5月7日出版的《自然—地球科学》杂志发表了这项研究成果。
土壤可以是大气二氧化碳的源或汇，这取决于土壤有机碳（SOC）对气候变暖和植物生产力变化的反应。尽管变暖通常会加速SOC的分解，但植物生产力变化的影响尚不清楚。研究组使用变化空间替换方法来分析SOC测量值的全局数据集，精确到1 米。
结果发现，变暖导致的0-0.3m表层土壤中SOC的减少逐渐被植物生产力的提高所抵消，但在0.3-1m底土中加剧，直到植物生产力提高超过30%的阈值。因此，要完全抵消变暖导致的土壤表层SOC减少，需要不切实际地提高植物生产力，尽管不同生态系统之间存在很大差异。
土壤碳氮比是SOC反应方差的主要预测因素，因为该比值决定了碳损失期间释放的氮是否满足额外植物生长的要求，或者是否必须从土壤有机质中开采额外的氮。这种采矿加速了SOC的损失，特别是在底土中，那里的土壤碳氮比低于表土。研究组得出结论，在全球范围内，植物生产力的提高可能会加剧气候变暖下SOC的损失，特别是在底土中。
附：英文原文
Title: Increased plant productivity exacerbates subsoil carbon losses under warming via nitrogen mining
Author: Wang, Mingming, Zhang, Shuai, Wang, Guocheng, Xiao, Liujun, Gu, Baojing, Zheng, Mianhai, Niu, Shuli, Yang, Yuanhe, Luo, Yiqi, Zhang, Ganlin, Shi, Zhou, Luo, Zhongkui
Issue&Volume: 2025-05-07
Abstract: Soils can be either a source or sink of atmospheric CO2 depending on how soil organic carbon (SOC) responds to climate warming and changes in plant productivity. Whereas warming typically accelerates SOC decomposition, the effect of plant productivity changes remains unclear. Here we use a space-for-change substitution approach to analyse a global dataset of SOC measurements down to 1metre. We find that warming-induced SOC reduction in the 0–0.3-m topsoil is gradually offset by increasing plant productivity but exacerbated in the 0.3–1-m subsoil until plant productivity increase crosses a threshold of 30%. Consequently, entirely offsetting warming-induced SOC reduction in the top metre of soil requires an unrealistically high increase in plant productivity, albeit with substantial variance across ecosystems. Soil carbon-to-nitrogen ratio is the dominant predictor of the variance in SOC response, as this ratio determines whether nitrogen released during carbon loss meets the requirement for additional plant growth or whether additional nitrogen must be mined from soil organic matter. Such mining accelerates SOC losses, particularly in the subsoil, where the soil carbon-to-nitrogen ratio is lower than in topsoils. We conclude that globally, increased plant productivity may exacerbate SOC losses under climate warming, particularly in the subsoil.
DOI: 10.1038/s41561-025-01697-1
Source: https://www.nature.com/articles/s41561-025-01697-1