Purpose of Review: The effectiveness of wildfire suppression is difficult to define as it can be assessed against different objectives and at a range of scales. The influence of multiple variables make it a challenge to research. This two-part series presents a synthesis of the current understanding of the effectiveness of wildfire suppression determined from studies of observational data and incident records. Effectiveness is considered on four scales: flames, firelines, whole incidents, and landscapes. This first part provides an overview of wildfire suppression followed by a synthesis of research undertaken at flame and fireline scales.

Recent Findings: Wildfire suppression research has been undertaken at flame and fireline scales for different reasons. Laboratory experiments have been the main means for investigating suppression at the flame scale. These have been used to compare wildfire suppression chemicals and identify those that are most effective. Field observations of sections of fire perimeter have been used to investigate resource productivity and the effects that suppression efforts have on fire behavior to evaluate specific resource types and tactics.

Summary: There are many ways that wildfire suppression effectiveness can be defined and measured. These depend on the scale and purpose that they are considered. Wildfire suppression effectiveness research conducted at flame and fireline scales has provided a means for comparing and evaluating wildfire suppression chemicals and firefighting resources. These scales provide an opportunity for many variables to be closely examined. Laboratory experiments, typically conducted in combustion wind tunnels, allow some variables to be investigated in isolation and provide a means for repeated testing at the flame scale. Field observations and measurements made at the fireline scale can provide a realistic setting representative of the wildfire conditions where their findings will be applied.