Oral Session # 6: Fire Ecology I: Structure and Demographics
Presiding: R Parmenter
Monday, August 4. 8:00 AM to 11:30 AM, SITCC Meeting Room 105.

Can oak forest structure and sustainability be restored with prescribed fire alone?

Hutchinson, Todd *,1, Sutherland, Elaine2, Yaussy, Daniel1, 1 USDA Forest Service, NERS, Delaware, OH2 USDA Forest Service, RMRS, Missoula, MT

ABSTRACT- Witness trees recorded in the original land surveys (ca. 1800) indicate that oaks dominated presettlement upland forests in southeastern Ohio. Forest density estimates suggest that open woodlands (< 100 trees/ha) were uncommon but low-density forests (100-200 trees/ha) were the modal frequency class. Through the 1800s, nearly all forests were harvested, and fire was frequent until suppression began in 1923. After >75 years of effective fire suppression, current forests are more dense and gradually succeeding to dominance by shade-tolerant species (e.g., maples). In 1995 we initiated a long-term study at four 75 ha sites to determine the effectiveness of prescribed fire to improve oak regeneration and thus sustainability of the ecosystem. Most stands originated ca. 1870-1910. Prior to the reintroduction of fire, oaks comprised 67-72% of tree basal area and median tree density was 368 trees/ha. Shade tolerant species (e.g., maples) were abundant in the midstory and comprised >85% of saplings. Annual (1996-1999) and periodic (1996 and 1999) low-intensity fires were conducted on units at each site and an unburned unit served as a reference. By 1999, sapling densities were reduced by 85% on burned units, whereas overstory trees were largely unaffected. Hemispheric photographs taken in 1998 indicated that light availability was not significantly affected by fire. Without significant changes in overstory tree density and light availability on burned units, there was no significant difference in the relative abundance of large (> 30 cm height) oak seedlings among treatments by 2002. Large seedlings of shade-tolerant species were more abundant than oaks, and did not differ among fire treatments. We conclude that even repeated burns are inadequate to reduce forest density and improve oak regeneration in long-unburned forests of this region.

Key words: Quercus, light, fire, regeneration