UMBC Faculty CollectionYeakley, J. AlanColeman, David C.Haines, Bruce L.Kloeppel, Brian D.Meyer, Judy L.Swank, Wayne T.Argo, Barry W.Deal, James M.Taylor, Sharon F.2018-03-132018-03-132003Yeakley, J., Coleman, D. C., Haines, B. L., Kloeppel, B. D., Meyer, J. L., Swank, W. T., & ... Taylor, S. F. (2003). Hillslope Nutrient Dynamics Following Upland Riparian Vegetation Disturbance. Ecosystems, 6(2), 0154-0167.http://hdl.handle.net/11603/7859Per Portland State University, one or more authors of this paper were federal employees when contributing to this work and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law. See https://works.bepress.com/j_yeakley/6/.We investigated the effects of removing near-stream Rhododendron and of the natural blowdown of canopy trees on nutrient export to streams in the southern Appalachians. Transects were instrumented on adjacent hillslopes in a first-order watershed at the Coweeta Hydrologic Laboratory (35°03′N, 83°25′W). Dissolved organic carbon (DOC), K⁺, Na⁺, Ca²⁺, Mg²⁺, NO₃⁻-N, NH₄⁺-N, PO₄³−-P, and SO₄²− were measured for 2 years prior to disturbance. In August 1995, riparian Rhododendron on one hillslope was cut, removing 30% of total woody biomass. In October 1995, Hurricane Opal uprooted nine canopy trees on the other hillslope, downing 81% of the total woody biomass. Over the 3 years following the disturbance, soilwater concentrations of NO₃⁻-N tripled on the cut hillslope. There were also small changes in soilwater DOC, SO₄²⁻, Ca²⁺, and Mg²⁺. However, no significant changes occurred in groundwater nutrient concentrations following Rhododendron removal. In contrast, soilwater NO₃⁻-N on the storm-affected hillslope showed persistent 500-fold increases, groundwater NO₃−-N increased four fold, and streamwater NO₃−-N doubled. Significant changes also occurred in soilwater pH, DOC, SO₄²⁻, Ca²⁺, and Mg²⁺. There were no significant changes in microbial immobilization of soil nutrients or water outflow on the storm-affected hillslope. Our results suggest that Rhododendron thickets play a relatively minor role in controlling nutrient export to headwater streams. They further suggest that nutrient uptake by canopy trees is a key control on NO3−-N export in upland riparian zones, and that disruption of the root–soil connection in canopy trees via uprooting promotes significant nutrient loss to streams.16 pagesen-USThis item may be protected under Title 17 of the U.S. Copyright Law. It is made available by UMBC for non-commercial research and education. For permission to publish or reproduce, please contact the author.biogeochemistrydissolved organic carbonhillslope hydrologynutrient uptakesoilwater chemistrysouthern Appalachian mountainsstreamwater qualityvegetation removalwatershed managementwindthrowText