Data from: Hidden role of trophic cascade effects for soil carbon sequestration in alpine tundra

Large soil organic carbon (SOC) stocks in alpine tundra play a critical
role in the global carbon budget but are increasingly vulnerable to loss
under climate warming. These losses are partly driven by vegetation
shifts, such as the upward migration of herbaceous plants, which alter
soil food web structure and its influence on SOC sequestration. However,
although interactive effects between these processes are expected, they
remain largely unclear or effectively hidden. Here, we conducted a
13C-labeled glucose tracing experiment in the alpine tundra of Changbai
Mountain to investigate how upward migration of Deyeuxia angustifolia
affects soil food web structure, energy flows, and ultimately SOC
sequestration. Compared with soils without migration (NM), heavily
herb-migrated (HM) soils showed intensified carbon fluxes within trophic
cascade effects, increasing carbon transfer to higher trophic levels,
including fungivores, omnivores-predators, plant-parasites, meso- and
macrofauna. Predators in HM soils exhibited progressively increasing ¹³C
assimilation over the 30-day period, while microbivores showed a 5-day lag
behind microbial ¹³C uptake. This predator-driven energy dissipation was
2-14 times greater in HM than in NM soils and constituted an inefficient
carbon sequestration pathway, that limited the formation of stable carbon
pools. As a result, SOC turnover in HM soils was more than 50 % lower than
in NM soils, indicating a shift toward less stable carbon forms and
reduced net accumulation. Overall, our findings demonstrate that soil food
webs play a pivotal role in both “belowground shaping” and “aboveground
feedback” processes during herbaceous plant migration, and that
strengthened trophic cascade effects redirect carbon flow toward
inefficient pathways, thereby constraining SOC sequestration in alpine
tundra ecosystems.