Soil Respiration Hotspots in Temperate Tidal Restored and Natural Wetlands

Abstract:

Whether a wetland is a carbon dioxide sink or source is dependent on the balance of photosynthesis and ecosystem respiration. As temperature is increasing, respiration may accelerate over photosynthesis, yet the dynamics in tidal temperate wetlands are not clear as the tidal influence impact respiration egress of the soil. Here, we investigated soil respiration of two different microsites in each a natural and a restored wetland over a range of temperature and water level conditions over the growing season. Soil respiration increased with incoming tide and was lowest under water-inundated conditions. Mudflat microsites tended to have higher soil respiration than vegetated areas, indicating sufficiently high carbon input into non-vegetated areas for high respiratory fluxes. Whereby Spartina alterniflora microsites exhibited on average lower soil respiration fluxes of about 13 micromol m^-2 s^-1, Spartina patens exhibited higher fluxes at about 38 micromol m² s^-1 with Phragmites australis intermediate soil respiratory fluxes. Largest spatial variation was observed for mudflat microsites.