二氧化碳含量的增加有利于C₄草的生产，这一成果由美国普林斯顿大学A. Carla Staver等合作取得。相关研究发表在2026年8月19日出版的国际学术期刊《自然》上。

大气CO₂浓度的升高正通过间接气候效应和对植物表现的直接影响，影响着全球陆地生物圈。在热带森林中，长期监测表明存在一个由CO2驱动的显著碳汇。以C₄草本植物为主的热带和亚热带稀树草原贡献了约30%的陆地净初级生产力，但缺乏相应的CO2响应长期分析。在此，研究人员通过对70项CO2添加实验的荟萃分析和来自南部非洲长达32年的原位野外观测，得出了一个清晰且一致的结果：CO2对野生C₄草类的施肥效应在干旱条件下是广泛的。在实验中，草类在较高CO2水平下降低了气孔导度，在减少水分损失的同时增加了碳获得。在野外，水分利用效率的提高转化为三十年来观测到的C4草类生物量增加。最后，通过社区土地模型（Community Land Model）的模拟表明，在未来条件下，CO2对C₄草类地上生产力的施肥作用可能持续增强。总之，这些结果挑战了C₄草类对CO2升高无响应的观点，反而表明南部非洲野外草类的年地上产量在三十年间增加了28%（CO2驱动的增加量为每年75.1 g m^-2，95%置信区间为74.5–75.8 g m-2，即0.37吨碳/公顷）。尽管这些碳的去向尚不确定（取决于与火灾、食草动物和木本植被的反馈），但其对全球碳循环的影响可能是深远的。

附：英文原文

Title: Increasing CO2 levels fertilize C4 grass production

Author: Simpson, Kimberley J., Staver, A. Carla, King, James A., Bond, William J., Coetsee, Corli, Pallett, Nita C. M., Pellegrini, Adam F. A., Raubenheimer, Sarah L., Ripley, Brad S., Val Martin, Maria, Osborne, Colin P.

Issue&Volume: 2026-08-19

Abstract: Rising atmospheric CO2 concentrations are impacting the global terrestrial biosphere through indirect climate effects and direct effects on plant performance. In tropical forests, long-term monitoring indicates a substantial CO2-driven carbon sink4. C4-grass-dominated tropical and subtropical savannas contribute approximately 30% of terrestrial net primary production5, and yet equivalent long-term analyses of CO2 responses are lacking. Here we show a clear and consistent result across a meta-analysis of 70 CO2-addition experiments and 32 years of in situ field observations from southern Africa: CO2 fertilization of wild C4 grasses is widespread in dry conditions. In experiments, grasses reduced stomatal conductance under higher levels of CO2, limiting water loss while increasing carbon gain. In the field, improved water use efficiency translated into increased C4 grass biomass production across three decades of observations. Finally, simulations via the Community Land Model6 suggest that CO2 fertilization of C4 grass aboveground productivity may continue to increase under future conditions. Together, these results challenge the view that C4 grasses are unresponsive to increasing levels of CO2, demonstrating instead that annual aboveground production of grasses in the field in southern Africa has increased by 28% over three decades (a CO2-driven increase of 75.1gm2 (95% confidence interval of 74.5–75.8gm2) or 0.37tonsCha1 of annual production). Although the fate of this carbon is uncertain (depending on feedbacks with fire, herbivory and woody vegetation), effects on the global carbon cycle may be profound.

DOI: 10.1038/s41586-026-10935-4

Source: https://www.nature.com/articles/s41586-026-10935-4