An integrated study to define fire relationships in wetland soils is described The objectives are to define the limits to combustion (ignition and burnout), model heat and vapor transport, and predict fire effects in organic soils. The goal is to develop models to predict the potential impacts of fire on organic soils from a wide range of wetland ecosystems. The study involves both laboratory experiments and field validation phases. Soil physical properties affecting combustion and heat transfer are quantified. Standard laboratory ignition tests are used to extend existing combustion limits models to wetland soils. Moisture and mineral contents are varied to determine and model the limits to ignition and combustion sustainability under conditions typically found throughout the hydroperiod. Controlled burning of large soil cores (0.022 m3) from wetlands in North Carolina, Alaska, and Michigan is used to validate combustion limits and measure heat and vapor transport, and nutrient fluxes. These data are used to extend an existing heat and vapor transport model to organic soils. Heat transfer is coupled with descriptions of plant morphology, rooting depth etc. to predict plant survival and regeneration. Analysis of the dependence of combustion and heat transfer on soil physical properties will be used to assess the range of wetland ecosystems to which models can be applied. Field burns are planned for 1993 and 1994 to validate ignition, burnout, heat transfer, and fire effects models.