Northern Canadian wetlands: Net ecosystem CO₂ exchange and climatic change

Northern Canadian peatlands represent a long term sink for atmospheric carbon dioxide (CO₂), however there is concern they may become a net source of CO₂ due to climatic change. Climatic change is expected to result in significant changes in regional hydrology in boreal and subarctic regions of Canada. A hydrologic model predicted a summer water table drop of 0.14 m in northern Canadian fens given an increase in summer temperature and rainfall of 3°C and 1 mm d^-1, respectively. Moreover, surface peat temperature increased by 2.3°C. Net ecosystem exchange of CO₂ was modelled using these modelled hydrologic and thermal changes with respiration:peat temperature and water table:net ecosystem production relationships developed from measurements at wetlands in northern Sweden and near Churchill, Manitoba. Model results indicate that the net atmospheric CO₂ sink function of fens may be enhanced under future 2 x CO₂ scenarios, while boss may become a net source of atmospheric CO₂. If the net ecosystem productivity response to the new hydrologic conditions was ignored then the model predicts a decrease in summer carbon storage for all peatland types.