Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland.
Climate Impacts Research Centre, Department of Ecology and Environmental Sciences, Umeå Universitet, Abisko, Sweden.
Elife. 2022 May 12;11:e78555. doi: 10.7554/eLife.78555.
Climate warming is releasing carbon from soils around the world, constituting a positive climate feedback. Warming is also causing species to expand their ranges into new ecosystems. Yet, in most ecosystems, whether range expanding species will amplify or buffer expected soil carbon loss is unknown. Here, we used two whole-community transplant experiments and a follow-up glasshouse experiment to determine whether the establishment of herbaceous lowland plants in alpine ecosystems influences soil carbon content under warming. We found that warming (transplantation to low elevation) led to a negligible decrease in alpine soil carbon content, but its effects became significant and 52% ± 31% (mean ± 95% confidence intervals) larger after lowland plants were introduced at low density into the ecosystem. We present evidence that decreases in soil carbon content likely occurred via lowland plants increasing rates of root exudation, soil microbial respiration, and CO release under warming. Our findings suggest that warming-induced range expansions of herbaceous plants have the potential to alter climate feedbacks from this system, and that plant range expansions among herbaceous communities may be an overlooked mediator of warming effects on carbon dynamics.
气候变暖正在释放世界各地土壤中的碳，构成了一种正反馈的气候影响。变暖还导致物种向新的生态系统扩展其分布范围。然而，在大多数生态系统中，尚不清楚扩展分布范围的物种是否会放大或缓冲预期的土壤碳损失。在这里，我们使用了两项全群落移植实验和一项后续的温室实验，以确定在高山生态系统中引入草本低地植物是否会影响变暖条件下的土壤碳含量。我们发现，变暖（移植到低海拔地区）导致高山土壤碳含量略有下降，但在低密度将低地植物引入生态系统后，其影响变得显著，增加了 52%±31%（平均值±95%置信区间）。我们提供的证据表明，土壤碳含量的下降可能是通过低地植物在变暖条件下增加根分泌物、土壤微生物呼吸和 CO2 释放来实现的。我们的研究结果表明，草本植物的变暖诱导的分布范围扩大有可能改变该系统的气候反馈，而草本植物群落之间的分布范围扩大可能是一个被忽视的变暖对碳动态影响的中介因素。
