Effects of repeated prescribed fires on the structure, composition, and regeneration of mixed-oak forests in Ohio
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Forest Ecology and Management. 218: 210-228.
This study quantifies prescribed fire effects at four sites in southern Ohio, from 1995 to 2002. Each site had three treatment units: an unburned control, a unit burned 2x (1996 and 1999), and a unit burned 4 x (1996-1999). Vegetation plots were stratified by an integrated moisture index (IMI) into xeric, intermediate, and mesic classes. Prior to treatments, oak (Quercus spp.) and hickory (Carya spp.) comprised 74-83% of basal area among sites but shade-tolerant species (e.g., Acer rubrum) were abundant in the midstory and completely dominated the sapling layer. Fires were conducted in March and April. Fire intensity, estimated by temperature-sensitive paints, was highest on the 2x burn units. Fires had little effect on large tree (>25 cm DBH) density and stand basal area. By contrast, the density of small trees (10-25 cm DBH) was reduced by 31% on 2x burn units and by 19% on 4x burn units. "Fire-induced" mortality (i.e., mortality on burn units above that of unburned units) for the most common species of small trees was: A. rubrum = 33%; Quercus alba = 17%; Carya spp. = 13%; Nyssa sylvatica = 10%; Acer saccharum = 4%; Quercus prinus = 2%. Sapling density was reduced by 86% on burn treatments. Despite reduced small tree and sapling densities on burned units, canopy openness, estimated by hemispherical photography, remained low (<6%). In general, the composition of tree regeneration was not substantially altered by fire treatments. On burn units, a significant initial decrease in A. rubrum seedling density and a significant increase in Liriodendron tulipifera from the seed bank did not persist throughout the study. Oak + hickory seedling density was not significantly affected by fire nor was the density of shade-tolerant seedlings. Post-treatment (2002) sampling of large seedlings (>30 cm height) indicated no significant differences in the abundance of oak + hickory nor that of shade-tolerant seedlings among fire treatments. For most vegetation response variables, fire effects tended to be similar among IMI classes. The application of fire alone, without partial harvesting, failed to improve oak regeneration consistently. However, given that two fires reduced stand density, the longer term application of periodic fire, coupled with natural gap dynamics, may still be a feasible management strategy for improving the sustainability of oak forests where harvesting is not permitted or desired.
KeywordsQuercus; Acer; oak-hickory forest; fire; prescribed burning; sustainability; mortality; central hardwoods region
Hutchinson, Todd F.; Sutherland, Elaine Kennedy; Yaussy, Daniel A. 2005. Effects of repeated prescribed fires on the structure, composition, and regeneration of mixed-oak forests in Ohio. Forest Ecology and Management. 218: 210-228.