Prescribed burning and understory composition in a temperate deciduous forest, Ohio, USA

Since the advent of widespread suppression in the mid-20th century, fire has been relatively rare in deciduous forests of the eastern United States. However, widespread prescribed burning has recently been proposed as a management tool to favor oak (Quercus spp.) regeneration. To examine the potential effects of fire introduction on the understory community, we experimentally burned small plots and simulated aspects of fire at a forested site in southeastern Ohio. Treatments included two burn intensities, litter removal, increased soil pH, and a control. Treatments were arranged in a randomized block design in two landscape positions (dry upland and moist lowland) and two canopy conditions (gap, no gap). Post-fire vegetation was identified to species, and stems were counted 1, 3, and 14 months after burning. Community composition was more strongly affected by fire in upland plots than in lowlands, but was not affected by canopy openness. Both cool and hot burns reduced post-fire seedling emergence of Acer rubrum, a common overstory tree. Hot burns facilitated germination of Vitis spp., Rhus glabra, and Phytolacca americana, species common in disturbed habitats, and increased graminoid abundance. Cool burns and litter removal facilitated germination of Erechtites hieracifolia and Liriodendron tulipifera suggesting that litter removal is the mechanism by which fire favors colonization. These results suggest that fire applied frequently in the Central Hardwoods Region would cause compositional shifts to graminoids and disturbance-adapted forbs by increasing germination from the seed bank. Fire did not favor species with dormant underground buds, as studies in other ecosystems would suggest. Vegetational responses were noticeably weaker in the second year after burning, indicating that a single fire has only a short-term effect.