https://doi.org/10.22541/essoar.175855718.85179582/v1

Ivanova, K., Virkkala, A.-M., Vogt, J., et al. (2025). Small-scale spatial variability in carbon fluxes driven by soil and vegetation characteristics in wetlands of Trail Valley Creek, Canada. ESS Open Archive. https://doi.org/10.22541/essoar.175855718.85179582/v1

The microtopography of Arctic tundra and the associated soil moisture gradient influence the net ecosystem-atmosphere exchange of methane (CH4) and carbon dioxide (CO2). We aimed for quantifing fine-scale variability in a permafrost ecosystem. We measured growing-season carbon fluxes with closed chambers at Trail Valley Creek, Canada from 2022 to 2024. A total of six landforms were sampled, spanning a wetness gradient from dry (upland tundra, gully) over intermediate (polygons, degraded wetland centers) to wet (transitional zones, trenches) microsites. All landforms were net sources of CH4; only trenches had high emissions, while the other landforms had emissions close to zero. Drier elements (upland tundra, polygons) were net CO2 sinks, while wetter depressions (gullies, degraded centers, transitional zones) were net sources; trenches were a wet exception that still acted as a sink. All fluxes were strongly influenced by temperature, peaking during the hot summer of 2023. CH4 flux variability was dominated by belowground variables (subsurface soil moisture and temperature). For CO2 fluxes, aboveground (air temperature, AT, and photosynthetically active radiation, PAR) and belowground drivers contributed equally. For CH4, setting up statistical models separately for each landform reduced errors but lowered R2, so this approach is preferable when the goal is to minimize absolute error. For GPP and ER, including landform information improved theestimation of fluxes. For NEE, a single model fit to all landforms was sufficient. These results show that field studies focusing on small-scale variability in carbon fluxes should prioritize detailed soil-layer measurements, AT, and PAR, while vegetation metrics are optional.

https://essopenarchive.org/doi/pdf/10.22541/essoar.175855718.85179582/v1?download=true&redirectToLatest=false