State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
China National Botanical Garden, Beijing, China.
Glob Chang Biol. 2023 Aug;29(16):4686-4696. doi: 10.1111/gcb.16798. Epub 2023 May 28.
Climate-induced changes in snow cover can greatly impact winter soil microclimate and spring water supply. These effects, in turn, can influence plant and microbial activity and the strength of leaching processes, potentially altering the distribution and storage of soil organic carbon (SOC) across different soil depths. However, few studies have examined how changes in snow cover will affect SOC stocks, and even less is known about the impact of snow cover on SOC dynamics along soil profiles. By selecting 11 snow fences along a 570 km climate gradient in Inner Mongolia, covering arid, temperate, and meadow steppes, we measured plant and microbial biomass, community composition, SOC content, and other soil parameters from topsoil to a depth of 60 cm. We found that deepened snow increased aboveground and belowground plant biomass, as well as microbial biomass. Plant and microbial carbon input were positively correlated with grassland SOC stocks. More importantly, we found that deepened snow altered SOC distribution along vertical soil profiles. The increase in SOC caused by deepened snow was much greater in the subsoil (+74.7%; 40-60 cm) than that in the topsoil (+19.0%; 0-5 cm). Additionally, the controls on SOC content under deepened snow differed between the topsoil and subsoil layers. The increase in microbial and root biomass jointly enhanced topsoil C accumulation, while the increase in leaching processes became critical in promoting subsoil C accumulation. We conclude that under deepened snow, the subsoil had a high capacity to sink C by incorporating C leached from the topsoil, suggesting that the subsoil, originally thought to be climate insensitive, could have a higher response to precipitation changes due to vertical C transport. Our study highlights the importance of considering soil depth when assessing the impacts of snow cover changes on SOC dynamics.
气候引起的积雪变化会极大地影响冬季土壤微气候和春季水资源供应。这些影响反过来又会影响植物和微生物活动以及淋溶过程的强度，从而改变不同土壤深度的土壤有机碳（SOC）分布和储存。然而，很少有研究探讨积雪变化将如何影响 SOC 储量，而对于积雪对土壤剖面中 SOC 动态的影响则知之甚少。本研究通过在内蒙选择 11 个沿 570km 气候梯度分布的雪堤，覆盖干旱、温带和草甸草原，测量了从表土到 60cm 深度的植物和微生物生物量、群落组成、SOC 含量和其他土壤参数。结果表明，积雪的加深增加了地上和地下植物生物量以及微生物生物量。植物和微生物碳输入与草地 SOC 储量呈正相关。更重要的是，我们发现积雪的加深改变了 SOC 沿垂直土壤剖面的分布。与表土（+19.0%；0-5cm）相比，积雪的加深导致 SOC 在亚土层（+74.7%；40-60cm）中的增加更大。此外，积雪对亚土层和表土层 SOC 含量的控制因素不同。微生物和根生物量的增加共同促进了表土的碳积累，而淋溶过程的增加则对促进亚土碳积累变得至关重要。本研究认为，在积雪的影响下，亚土具有从表土淋溶下来的碳汇能力，这表明原本被认为对气候不敏感的亚土，由于垂直碳输送，对降水变化的响应可能更高。本研究强调了在评估积雪变化对 SOC 动态的影响时考虑土壤深度的重要性。
