College of Life Sciences, Zhejiang University, Hangzhou, China.
Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia.
Nature. 2024 Jun;630(8017):660-665. doi: 10.1038/s41586-024-07491-0. Epub 2024 Jun 5.
The capacity for terrestrial ecosystems to sequester additional carbon (C) with rising CO concentrations depends on soil nutrient availability. Previous evidence suggested that mature forests growing on phosphorus (P)-deprived soils had limited capacity to sequester extra biomass under elevated CO (refs. ), but uncertainty about ecosystem P cycling and its CO response represents a crucial bottleneck for mechanistic prediction of the land C sink under climate change. Here, by compiling the first comprehensive P budget for a P-limited mature forest exposed to elevated CO, we show a high likelihood that P captured by soil microorganisms constrains ecosystem P recycling and availability for plant uptake. Trees used P efficiently, but microbial pre-emption of mineralized soil P seemed to limit the capacity of trees for increased P uptake and assimilation under elevated CO and, therefore, their capacity to sequester extra C. Plant strategies to stimulate microbial P cycling and plant P uptake, such as increasing rhizosphere C release to soil, will probably be necessary for P-limited forests to increase C capture into new biomass. Our results identify the key mechanisms by which P availability limits CO fertilization of tree growth and will guide the development of Earth system models to predict future long-term C storage.
陆地生态系统在 CO 浓度升高的情况下固碳（C）的能力取决于土壤养分的供应情况。先前的证据表明，在磷（P）匮乏的土壤上生长的成熟森林在高浓度 CO 下固碳的能力有限（参考文献），但对生态系统 P 循环及其对 CO 的响应的不确定性是对气候变化下陆地 C 汇进行机制预测的一个关键瓶颈。在这里，通过为暴露在高浓度 CO 下的有限 P 成熟森林编制第一个全面的 P 预算，我们表明，土壤微生物捕获的 P 极有可能限制生态系统 P 循环和植物吸收的 P 可用性。树木有效地利用了 P，但微生物对矿化土壤 P 的先占似乎限制了树木在高浓度 CO 下增加 P 吸收和同化的能力，因此也限制了它们固碳的能力。刺激微生物 P 循环和植物 P 吸收的植物策略，例如增加根际 C 向土壤的释放，可能对于 P 限制的森林增加新生物量中的 C 捕获是必要的。我们的结果确定了 P 供应限制树木生长 CO 施肥的关键机制，并将指导地球系统模型的开发，以预测未来的长期 C 储存。
