The Impact of Experimental Temperature and Water Level Manipulation on Carbon Dioxide Release in a Poor Fen in Northern Poland

Peatlands are ecosystems for which carbon budget relies strongly on the meteorological and hydrological conditions. Here, using a manipulative field experiment, we measured ecosystem respiration (R-ECO) over two years (2013-2014) in a poor fen in Poland to estimate the carbon emission in a changing climate. The experiment consisted of warming (open-top chambers - OTC) and water table manipulation. The application of OTC increased the mean values of daily maximum air temperature by approx. 1.1-1.8 A degrees C. Warming or the increased water table depth separately resulted in an increase in ecosystem respiration by approx. 0.1 mu mol CO2 m(-2) s(-1) and 0.3 mu mol CO2 m(-2) s(-1), respectively. However, our results show also the additive nature of warming and water table drawdown impact on daily R-ECO during the studied years (2013-0.80 mu mol CO2 m(-2) s(-1) and 2014-1.16 mu mol CO2 m(-2) s(-1)). With the natural dry period event which occurred in 2014, the seasonal R-ECO increased by approx. 0.2 mu mol CO2 m(-2) s(-1) as compared to the previous year. Projected global warming will therefore significantly enhance C loss from poor fens in this region of Europe.