Water Quality Effects of Clearcutting Upper Coastal Plain Loblolly Pine Plantations

Abstract
The effect of clearcutting loblolly pine (Pinus taeda L.) on concentrations of sediment and nutrients in stormflows was studied on small catchments near Lexington, TN. The plantations were established on eroded and abandoned agricultural lands with fragile soils. Soil series on the catchments include Lexington silt loam (fine‐silty, mixed, thermic Typic Paleudalfs), Providence sill loam (fine‐silty, mixed, thermic Typic Fragiudalfs) and Ruston sandy loam (fine‐loamy, silicious, thermic Typic Paleudults). Eight catchments (0.17–0.56 ha) were instrumented with flumes equipped with water stage recorders to measure stormflow and Coshocton wheel samplers to obtain integrated samples of the flow. Plantations on four catchments were clearcut; the other four were left as uncut controls. Stormflow samples were analyzed for sediment‐phase total Kjeldahl nitrogen (TKN) and total phosphorus (TP) and solution‐phase TKN, TP, and potassium (K). Results indicated that a third or more of the TKN and two‐thirds of the TP exported in stormflow from the catchments was via sediment. Solution‐phase TKN and TP concentrations in stormflow were similar on clearcut and control catchments. Solution K concentrations were consistently higher from clearcut catchments. Rainfall inputs of TKN, TP, and K exceeded stormflow losses. The study demonstrated that pine plantations established on fragile soils can be clearcut without significant impact on water quality if recommended practices are used.

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