Fire is one of the key disturbances affecting aspen (Populus tremuloides Michx.) forest ecosystems within western Canadian wildlands, including Elk Island National Park. Prescribed fire use is a tool available to modify aspen forests, yet clearly understanding its potential impact is necessary to successfully manage this disturbance.Undesirable social consequences of severe, deep burning ground fires include smoke generation and impaired vegetation re-growth. Data on the soil and duff moisture conditions under which ground or subsurface fires may start in aspen are presented, as well as experimental test fire results. Different topographic positions, plant communities and seasons were factored into the research design. The Duff Moisture Code and Drought Code components of the Canadian Forest Fire Weather Index System were calculated and factors including duff moisture content, bulk density and inorganic content measured at the time of ignition. Probability of sustained smouldering ignition models were developed for the aspen forest fuel type, with values of 27 for DMC and 300 for DC at the 50% probability of ignition level. This information will improve the capability to effectively manage aspen using fire in central Alberta.