How resilient is the Puergschachen bog as a GHG sink over 7.5 years?

Description

Peatlands naturally act as carbon and water (H2O) sinks, but due to degradation caused by drainage and drought, peatlands can become a carbon source and lose H2O.
Puergschachen is an ombrotrophic bog situated in the inner-alpine Enns valley at an altitude of 632 m in the Eastern Alps of Austria. The raised bog covers an area of about 62 ha and is moderately degraded, as indicated by a shift in vegetation composition due to the birch encroachment and the loss of specialized bog hollow species. The bog is threatened by drainage for intensive agriculture in the surrounding area, droughts and rising air temperature due to climate change.
The eddy covariance (EC) technique was employed to provide a continuous quantification of the vertical turbulent greenhouse gas (GHG) exchange of H2O, carbon dioxide (CO2) and CH4 between the bog and the atmosphere for 7.5 years (mid-2015 to 2022). Vegetation indices were used to account for the vegetation development of the studied ecosystem.
We quantified the interannual and seasonal variability of H2O, CO2 and CH4 fluxes and evaluated the underlying factors being responsible for these variations. Furthermore, the influence of climatic stressors on the carbon and water fluxes of the bog was investigated. The annual precipitation of the last 5 years (2018-2022) was below the mean annual precipitation of 1233 mm (1985-2022), while the annual mean annual air temperature showed a strong increase, especially in the last 10 years, from 7.4°C (1985-2022) to 8.2°C (2012-2022).
In 5 out of 7 years, the Puergschachen bog was a carbon sink. However, when considering the radiative forcing of CH4, the bog only was a GHG sink in 3 out of 7 years. Nevertheless, the bog was resilient enough to become a sink again after a particularly dry year. In all the years studied, the bog had a positive climatic water balance, as the annual evapotranspiration rate was lower than the annual precipitation.

Period	19 Sept 2024
Event title	international Peatland Science Conference
Event type	Conference
Location	Freising, Germany, BavariaShow on map
Degree of Recognition	International