Effect of Drainage and Management Practices on Hydrology of Pine Plantation
This paper reviews results of long-term studies, initiated in the late 1980s, to determine the hydrologic and water quality impacts of drainage and related water and forest management practices on a poorly drained site in Carteret County, North Carolina. Three watersheds, each approximately 25 ha, were instrumented to measure and record drainage rate, water table depth, rainfall and meteorological data. Data continuously collected on the site since 1988 include response of hydrologic and water quality variable for nearly all growth stages of a Loblolly pine plantation. Studies were conducted to develop and test models for predicting the hydrology of drained forested lands, and to determine the effects of thinning, harvesting, regeneration, controlled drainage, and related water management practices on hydrology and drainage water quality. This paper summarizes the principal findings of those studies. Data for drainage outflow rates and water table elevations were used to determine field effective hydraulic conductivity, K, of the profile at various stages of the production cycle. K values of the top 90 cm of the profile for mature plantation forest were 60 to 95 m/day, which were 20 to 30 times the values given in the soil survey for the Deloss series. Harvest did not appear to affect those values, but site preparation for regeneration, including bedding, reduced the effective K to values typically assumed for this series, 3.6 m/d for the top 45 cm and 1.6 m/d for deeper layers.