2006 journal article

Hydrologic and water quality effects of thinning loblolly pine

Transactions of the ASABE, 49(3), 645–654.

By: J. Grace, R. Skaggs* & G. Chescheir*

Source: NC State University Libraries
Added: August 6, 2018

Forest operations such as harvesting, thinning, and site preparation can affect the hydrologic behavior ofwatersheds on poorly drained soils. The influence of these operations conducted on organic soil sites can be more pronouncedthan on mineral soil sites due to the differences in bulk density and soil moisture relationships that exist between mineral andorganic soils. This article reports the results of a study to evaluate the effect of thinning on the hydrology and water qualityof an artificially drained pine plantation watershed on organic soils in eastern North Carolina. Outflow, water table depth,and water quality were monitored over a 3-year study period from paired 40 ha and 16 ha 15-year-old loblolly pine (Pinustaeda L.) plantations located in Washington County near Plymouth, North Carolina. Thinning increased daily outflow andpeak flow rates based on a paired-watershed study design. Mean daily outflow doubled and peak flow rates increased 40%on the thinned watershed in relation to the control. Treatment effects were also observed on nutrient loads following thethinning operation. Phosphorous, TKN, and TSS loads increased following thinning, while nitrate-nitrogen loads decreasedfollowing thinning. These differences in hydrologic behavior are primarily attributed to the reduction in evapotranspiration that resulted from thinning.