Monday, 17 November 2003
Effects of prescribed fire on light and canopy structure in an Appalachian hardwood forest on the Cumberland Plateau, KY
In the past 50 years there has been a documented decline in the natural regeneration of oaks (Quercus spp.), which has been attributed in part to an increase in competition and shading from more shade tolerant species such as red maple (Acer rubrum) and American beech (Fagus grandifolia). In the absence of periodic natural and anthropogenic disturbances such as fire, these species have increased in abundance, successfully out-competing oak seedlings and saplings in the low light levels created by closed canopies. This study was designed to determine if single or repeated prescribed fires could be effective as a management tool for increasing light at the seedling level. Hemispherical photography and densiometer readings were used to measure light availability before and after a single prescribed fire (repeated fires will be implemented next year). The effects of fire on canopy structure, combined with a recent ice storm, have resulted in highly variable changes in canopy structure and light availability to the forest floor. An overall increase in light was detected on burned sites, due to an increase in canopy openness and the extensive removal of the midstory stratum. This result differs from previous research in this region, which found minimal effects of a single fire on light availability. Explanations for this difference include the fact that prescribed fires in this study were more intense than expected, and occurred in combination with ice storm damage to the overstory. Past disturbance regimes in this region were undoubtedly far more complex than can be mimicked with management prescribed burns alone, complicating efforts to assess the potential of prescribed fire as a tool to improve oak regeneration.