Baltic raised bog carbon dioxide balance dynamics and its biophysical determinants - Kusowo case study

Peatlands are ecosystems with relatively low net productivity but a long-term carbon storage period (thousands of years). This carbon stock is continuously related to its hydrogenic origin, resulting in the high sensitivity of peatlands to hygrothermal factors such as temperature and precipitation. Changing the balance of temperature and wetness in peatlands may stimulate higher ecosystem respiration and/or reduce the photosynthetic capacity of plants and consequently shift the peatland from net sinks to sources of CO₂ to the atmosphere. Thus, the peatland-climate interaction study is crucial for understanding and predicting their faith in the future.

Since July 2019, the eddy covariance (EC) technique has been used to monitor CO₂/H₂O net fluxes at a baltic raised bog in Bagno Kusowo Nature Reserve, northern Poland (53.82 N, 16.59 E, 144 m a.s.l.). This peatland started formatting thousands of years ago and currently reaches up to 8 m of peat depth. The measurement tower works in collocation with the meteorological station, thus the standard meteorological parameters are measured along with flux observations. These common measurements were the basis for estimating peatland carbon dioxide balance and its relation to biophysical factors.

An early start of vegetation (March-April) on the baltic raised bog was noted, as well as predominant emissions from the peatland in mid-summer (August). During 2.5 years of measurements, the peatland in Kusowo was both a net sink and a source of CO₂ on an annual basis. The negative impact of lowering the water table level on the CO₂ balance (higher emissions) is more noticeable during the growing season when higher temperatures intensify the respiration processes.