Research

Occurrences of Surface Runoff from Georgia Piedmont Planted Forests

Surface runoff is not commonly considered a problem in forests. However, massive site disturbance occurring from normal practices of logging compaction and site preparation can cause production and movement of muddy water with the potential for disruption of aquatic stream life. Information on frequency of site preparation runoff has never been published inside the US. Two clearcut, bedded, and planted areas plus an uncut reference area were evaluated for overland flow exiting the managed area and entering the buffer strip. Runoff cups were established at 30 m intervals along the upper boundaries of streamside management zones (SMZs). Absence or presence of runoff was tallied for events exceeding 13 mm and concentrated flow tracks (CFTs) were grab-sampled during large storms. Mean runoff cup response was 9.7% from the plantations and 2.2% for the reference. Cup responsiveness and bare ground decreased from the first to the second year after planting. Response frequency was best correlated to rainfall factors “R” from the Revised Universal Soil Loss Equation, total storm depth, and 24-hour and 6-hour maximum intensities. Runoff locations were well distributed and some CFTs fully penetrated the SMZ. Water quality from site prepared forests was also studied. Mean plantation concentrations of dissolved nitrates, dissolved phosphates and suspended solids were 2.1, 0.21, 54 mg/L the first year, and 0.1, 0.12, 36 mg/L the second year, respectively. These values were generally in the range of other intermittent streams from site prepared areas in the southeast but above reference stream targets for undisturbed perennial streams.