First-order fire effects
n. Direct effects of the combustion process on the environment
First-order fire effects occur during and immediately after a fire and are primarily heat-induced chemical processes. According to Reinhardt and others (2001), first-order effects occur during a fire or within seconds or minutes afterward. According to Ryan and Elliot (2005), they occur within hours of or up to days after the fire. Because of this ambiguity, it is best to identify the timeframe referred to when using this term. First-order fire effects include injury to organisms or immediate mortality, fuel consumption, smoke production, and soil heating (Reinhardt and others 2001; Ryan and Elliot 2005).
First-order fire effects are not caused by interaction of fire or fire-caused stress with other influences, such as postfire weather, animal use, or fungal infection. First-order fire effects are sometimes called “immediate” or “direct” fire effects. Contrast with “second-order fire effects.”