Restoration of an oak forest in east-central Missouri - Early effects of prescribed burning on woody vegetation

We investigated early effects of prescribed burning on the structure and species composition of woody plants in Cuivre River State Park (2750 ha), Lincoln County, Missouri, USA, where a program of prescribed burning in forest understory was instituted to return the vegetation to conditions similar to those found at the time of European settlement. Prescribed burning in forest was initiated in 1989 and approximately 17% of the park is now burned every other year. We compared woody vegetation in 34 0.05 ha plots in burned sections of the park and in 34 0.05 ha plots in unburned sections of the park. Burned areas had experienced two to four bums at the time vegetation was sampled in 1996. Burned areas had significantly fewer small trees, fewer live woody shrubs, and less foliage in the understory (1.5-10 m) than did unburned areas. Small individuals of several species (e.g., Ulmus americana) were less abundant on burned areas and, overall, similarity of sample plots (based on basal areas of small trees) was significantly greater within burned areas than between burned and unburned areas. There were no differences in overstory structure or species composition that could be attributed to burning. Direct gradient analyses indicated that environmental factors (e.g., slope, elevation, aspect) accounted for some of the variation in species composition among plots but also indicated that burned and unburned plots did not differ consistently with respect to environmental factors. Thus, observed differences in vegetation structure and composition between burned and unburned areas of the park are due to the burning program and not to pre-existing differences in environmental factors (e.g., topography). Results to date reflect relatively short-term (<10 years) responses to burning. It is expected that changes in canopy composition and structure will occur over time. (C) 2000 Elsevier Science B.V. All rights reserved.