Speaker
Description
Peatlands store a disproportionately large share of global soil carbon, yet their stability is increasingly threatened by drying-induced degradation. Such degradation may create conditions that facilitate colonization of earthworms, although they are typically absent from waterlogged peat soils. However, how earthworm colonization alters peatland carbon dynamics remains poorly understood. Here, we used a 280-day mesocosm experiment with intact peat soil columns to investigate how earthworms and their densities influence carbon pools, nitrogen availability, and microbial processes across soil depths (surface: 0-10 cm; subsurface: 10-20 cm). Our results showed that earthworm altered soil carbon dynamics in a depth-dependent manner. Total carbon increased in surface soils under low earthworm density, but remained relatively stable in subsurface soils. In contrast, dissolved organic carbon (DOC) declined significantly by 16–37% across both soil depths, with stronger reductions at higher earthworm density. Phenolic compounds showed limited or no consistent responses to earthworm addition. Earthworm altered nitrogen dynamics by affecting both total and dissolved nitrogen pools. Total nitrogen increased in surface soils under low earthworm density, consistent with the pattern observed for total carbon, whereas dissolved nitrogen increased substantially across treatments, indicating enhanced nitrogen availability. Besides, earthworm suppressed β-1,4-glucosidase activity by 20% and 56% in surface soils under low and high densities, respectively, while enhancing both β-1,4-glucosidase and β-1,4-cellobiohydrolase activities in subsurface soils. Structural equation modelling further revealed distinct regulatory pathways across depths: surface DOC declined mainly through direct earthworm effects, whereas subsurface DOC was controlled indirectly through a moisture-mediated β-1,4-cellobiohydrolase pathway. Together, these results demonstrate that earthworms regulate carbon processing in alpine peat soils in a depth-dependent manner, with density-dependent effects on carbon turnover and retention. Our findings highlight the importance of soil fauna in regulating peatland carbon dynamics and call for greater consideration of faunal-driven processes under peatland degradation.
| Status Group | Postdoctoral Researcher |
|---|---|
| FOR TALKS: Poster Presentation Option | Yes, I’m willing to present as a poster. |