PARENT SESSION
Organized Oral Session 37: Post-fire conversion of forest to non-forest: Do we need new theory?
Organizer(s): RG Balice, B Romme, and TW Swetnam
Wednesday, August 10, 1:30 PM - 5:00 PM, Meeting Room 511 C, Level 5, Palais des congrès de Montréal
Persistent openings following high-severity fire in ponderosa pine forests of the Colorado Front Range: Comparison of historical processes and recent large fires.
Kaufmann, Merrill*,1, Huckaby, Laurie1, Fornwalt, Paula1, 1 USDA Forest Service, Fort Collins, CO, USA
ABSTRACT- The 2002 Hayman fire severely burned the ponderosa pine/Douglas-fir landscape at Cheesman Lake in the Colorado Front Range. Research on this landscape prior to the Hayman fire provides an exceptional opportunity to compare a recent severe fire and its landscape effects with historical fire and landscape ecology. A distinctive feature of historical fire behavior in this landscape was periodic mixed severity fire that resulted in a complex, dynamic landscape mosaic featuring openings and ponderosa pine woodland, with most Douglas-fir confined to north aspects. Historical fire rotations were about 75 years, and 460 years for stand replacement fires. Historical fires often exceeded 10 or 15 km2 and burned for several months. Resulting patch sizes were highly variable but generally less than 30 ha, reflecting diversity in fire behavior influenced by tree density and topography, and diversity in spatial and temporal patterns of subsequent tree recruitment. Exclusion of fire and grazing during the 20th century resulted in substantial increases in forest density and ingrowth of Douglas-fir. In contrast to historical fires, the Hayman fire burned 24,000 ha in one day. While a few small patches of trees survived in several protected locations, many areas of 1000 ha or more were completely killed by crown fire. Other Front Range fires since 1996 had similar outcomes but at reduced scales. Consequently, seed sources in coming years are severely limited, and large openings created by the Hayman fire are likely to persist for a century or more unless planted with seedlings. The large opening created by the Hayman fire poses new challenges in forest management, requiring a reforestation strategy that places the severely burned landscape on a trajectory of recovery that restores key spatial and temporal features of sustainable ponderosa pine landscapes.
Key words: ponderosa pine, mixed severity fire, extreme fire behavior, Hayman fire