Research Progress on Forest Ground Fires

Forest ground fire is a phenomenon of spontaneous combustion that occurs in humus or peat layers, representing an extreme fire behavior. Monitoring ground fires is difficult, and large-scale spreading can result in air pollution, extensive tree mortality, soil structure damage, and other consequences, posing a threat to the ecological environment. Starting from the ignition, spreading, and critical stages of ground fires, this paper analyzes the conditions for ignition and spreading, as well as the applicability of ground fire prediction and forecasting models. It investigates the critical conditions for the transition from smoldering to flaming (StF) phenomenon and analyzes the deficiencies of ground fire prediction, forecasting, and monitoring technologies. It indicates that the type of ignition source, physicochemical properties of combustibles, and environmental factors are the main factors influencing the ignition probability and spreading characteristics of ground fires. The critical stage of the StF phenomenon is related to changes in environmental conditions and sudden changes in physicochemical properties of combustibles. Indirect prediction methods using drought indices, groundwater levels, etc., both domestically and internationally, have errors in predicting ground fire occurrences. Existing fire monitoring equipment cannot meet the monitoring requirements for ground fires. This paper proposes future research directions for ground fires, providing reference for ground fire research.