SHORT- AND LONG-TERM EFFECTS ON FUELS, FOREST STRUCTURE, AND WILDFIRE POTENTIAL FROM PRESCRIBED FIRE AND RESOURCE BENEFIT FIRE IN SOUTHWESTERN FORESTS, USA

Prescribed and resource benefit fires are used to manage fuels in fire-prone landscapes in the Southwest. These practices, however, typically occur under different conditions, potentially leading to differences in fire behavior and effects. The objectives of this study were to investigate the effects of recent prescribed fires, resource benefit fires, and repeated fires in ponderosa pine forests, as well as recent resource benefit fires in pinyon-juniper woodlands. The Gila National Forest was the study area because it has a rich history of using fire as a restoration tool. In each vegetation type, fuels and stand structure were sampled using random plots stratified by burn severity in resource benefit fires. In ponderosa pine, sampling and analysis also included prescribed fire and areas subject to repeated resource benefit fires. To assess potential fire behavior, we used the crown fire behavior prediction model Nexus using ninetieth percentile weather conditions. In ponderosa pine forests, surface fuels were similar between prescribed fires and low severity resource benefit fires. However, resource benefit fires significantly reduced basal area, resulting in lower loading of canopy fuels and crown fire potential. Additionally, effects of resource benefit fire on stand structure and fuels seem to be sustained in areas that burned in two or three resource benefit fires in the last century. In pinyon-juniper woodlands, resource benefit low severity fires had no effect on surface or canopy fuel loads. Moderate severity resource benefit fires, on the other hand, did significantly reduce surface and canopy fuel loads. Results from this study are pertinent to fire and fuels managers throughout the southwestern United States who utilize prescribed and resource benefit fire to reduce fuel loads and restore historical forest conditions.