Harvesting effects on the hydrology of wet pine flats

Abstract

Wet pine flats are some of the most productive and intensively-managed wetland forests in the eastern United States. Wet-weather logging of these sites causes extensive rutting and churning of the soil surface and may alter the subsurface flow of soil water. An operational-scale experiment was established in 20-year-old loblolly pine (Pinus taeda) plantations to determine the hydrologic response of wet pine flats to wet- and dry-weather harvesting operations. Three 19-ha treatment blocks were established in the coastal plain near Charleston, South Carolina. Site hydrology was monitored monthly with a 20 x 20 m grid of water table wells for 18 months prior to treatment installation. Three treatments were applied to each block: wet-weather harvesting, dry-weather harvesting, and a control (nonharvested). Prior to harvesting, the water table depths followed a uniform pattern throughout the sites with seasonal fluctuations between 5 and 75 cm below the soil surface. The uniform pattern and poor inherent drainage of the site prior to harvest was due to lack of surface topography and impedance of internal vertical drainage by a restricting Btg soil horizon. After harvesting, the hydrologic pattern changed by the degree of soil disturbance as defined by soil physical properties and microtopographic changes. Such hydrologic changes could influence long-term site productivity and interfere with management of this wetland ecosystem.