Carbon dynamics in north temperate drained peatlands

North temperate peatlands that historically experienced cold and saturated soil conditions are important potential sources of atmospheric methane and carbon dioxide owing to thousands of years of C fixation and peat accumulation with slow rates of decomposition. It has been estimated that about half of global wetlands have been lost due to intensive agricultural drainage, and expanding industrial and urban areas. Although considerable attention has focused on agricultural management practices that can increase the rate of soil carbon accumulation, the loss of carbon from cultivated organic soils can also play a mainly negative role in organic matter accumulation. These regions also play an important role in global climate partially due to the potential for positive carbon-cycle feedbacks associated with the interaction between soil temperature and moisture. The water table position usually acts as the dominant control on methane (CH4) and carbon dioxide (CO2) emissions in such drained wetlands. Lower water tables caused by drainage generally increase CO2 emissions and reduce atmospheric CH¬4 fluxes and the organic matter can switch from a net C sink to a source. This study seeks to quantify the influence of water management on cultivated organic soils in northern Indiana. The Variable Infiltration Capacity (VIC) macroscale hydrologic model was modified to represent net primary productivity (NPP) and sub-field variability in water table position by integrating a modified topographic wetness index approach. Methane and carbon dioxide emissions are simulated using soil temperature, water table position and NPP generated from the VIC model and evaluated using CO2 flux measurements, combined with periodic measures of photosynthetic activity, water table height and soil moisture measurements. In order to understand the changing environmental condition and carbon dynamics in managed peatlands from 1916-2006, we will investigate the thermal and moisture regimes, for both simulated drained and undrained conditions.