Long-term effects of a prescribed fire regime on tree seedling density in an oak-hickory woodland

After decades of fire suppression, land managers in the Missouri Ozark Highlands began applying prescribed fire to promote the regeneration of oak and hickory species, and to prevent the recruitment of mesophytic understory species into the overstory. In this study, 13 years of prescribed fire data were examined to determine the response of oak, hickory, and shortleaf pine tree seedling density, as well as the densities of various understory and fire tolerant species, after repeated lowto moderate-intensity periodic burns at the Ozark National Scenic Riverways. Seedling density data were collected preburn, then after 1, 2, 3, or 4 burns, in xeric and mesic woodland plots. Seedling density was greater in mesic woodlands than xeric woodlands, overall. Oak, hickory, and shortleaf pine seedling densities did not change due to the periodic prescribed fire regime. In xeric woodlands, seedling density increased for both intermediately understorytolerant and understory-intolerant seedlings, while fire-tolerant species seedling density increased. No long-term changes were significant in mesic woodlands, suggesting that prescribed fire may be affecting xeric woodlands more intensely than mesic areas, and that other ecological factors, not fire, are likely keeping understory-tolerant species at low densities. Since mesophication does not appear to be a prominent issue, and fire is disproportionately affecting xeric woodlands, recruitment may be improved by increasing the fire return interval to allow seedling growth.