The effect of prescribed fire on gap fraction in an oak forest understory on the Cumberland Plateau1,2

Chiang, J-M., M. A. Arthur, and B. A. Blankenship (Department of Forestry, University of Kentucky, Lexington, KY 40546-0073). The effect of prescribed fire on gap fraction in an oak forest understory on the Cumberland Plateau. J. Torrey Bot. Soc. 132: 432–441. 2005.—Excessive shade in the understory has been widely cited as the most important factor causing poor oak regeneration in eastern deciduous forests. We examined the effect of single and multiple fires on forest stand structure and the consequent impacts on the gap fraction measured in the understory. Differences in midstory stem density (stems 2–15 cm diameter at breast height; DBH) before and after prescribed burning were highly correlated with fire frequency (R2 = 0.86, P < 0.01). On average, each additional burn reduced midstory stem density by ∼550 stems per hectare. Hemispherical photography showed an increase of 3.8 % in understory gap fraction in the first growing season after burning. This increase in gap fraction, which was likel...