Forest structure and fuels dynamics following ponderosa pine restoration treatments, White Mountains, Arizona, USA

Southwestern ponderosa pine forestecosystems have become uncharacteristically dense as a result of intensive livestock grazing, logging, and fire exclusion, which have contributed to a buildup of fuels and increased vulnerability to high-severity, landscape-scale crown fires. In 2002, we implemented a replicated ecological restoration experiment to (1) quantify site-specific reference conditions, (2) analyze effects of elevation on forest structure, surface fuels, and canopy fuels, (3) test responses to three treatments: control, full treatment, and burn-only, and (4) evaluate effectiveness of treatments for restoring attributes to near historical reference conditions. Reconstructed reference conditions showed that basal area(BA) averaged 9.2 m 2 ha � 1 and tree density averaged 86.2 trees ha � 1 across the site in 1880 prior to widespread fire exclusion, with the highest tree density values occurring at the two upper elevation sites. In 2002, prior to treatment, BA averaged 28.9 m 2 ha � 1