Hydrological controls on greenhouse gas fluxes and soil carbon quality in a Belgian floodplain

Summary

This field study examined how floodplain hydrology regulates soil carbon dynamics and greenhouse gas emissions in the Dijle valley, Belgium, across three water regimes during the wettest year on record. Temperature sensitivity of soil respiration varied with both soil moisture and water table depth: under fluctuating water tables, Q10 decreased with increasing moisture, whilst under high water tables, Q10 increased as conditions dried. The findings suggest that rewetting floodplains to maintain water tables just below the soil surface could reduce CO₂ emissions and their temperature sensitivity by constraining microbial activity, offering a nature-based climate regulation strategy.

UK applicability

UK floodplains share similar hydrological modification histories and temperate conditions to Belgium, suggesting these findings on water table management and GHG emissions are potentially applicable to UK floodplain restoration programmes. However, UK floodplains often occur in different geological and soil contexts (e.g. clay, peat, alluvial systems), requiring site-specific validation before generalisation.

Key measures

Soil CO₂ and CH₄ flux measurements; temperature sensitivity (Q10); basal respiration at 10°C (R10, µg CO₂-C gC⁻¹ h⁻¹); soil organic carbon, nitrogen, C/N ratio; thermal properties via differential scanning calorimetry (Energy Density, T50)

Outcomes reported

The study measured soil CO₂ and CH₄ fluxes across three hydrological zones in a Belgian floodplain during an exceptionally wet year, characterising soil carbon quality and its relationship to microbial respiration. It evaluated how water table position and land use (forest, grassland, cropland, marsh) influenced temperature sensitivity of soil respiration and methane emissions.

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