Title: Are nitrate exports in stream water linked to nitrogen fluxes in decomposing foliar litter?

Author: Piatek, Kathryn B.; Adams, Mary Beth.

Year: 2011

Publication: In: In: Fei, Songlin; Lhotka, John M.; Stringer, Jeffrey W.; Gottschalk, Kurt W.; Miller, Gary W., eds. Proceedings, 17th central hardwood forest conference; 2010 April 5-7; Lexington, KY; Gen. Tech. Rep. NRS-P-78. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 153-163.

Abstract: The central hardwood forest receives some of the highest rates of atmospheric nitrogen (N) deposition, which results in nitrate leaching to surface waters. Immobilization of N in foliar litter during litter decomposition represents a potential mechanism for temporal retention of atmospherically deposited N in forest ecosystems. When litter N dynamics switch to the N-release phase, litter N may contribute to N exports. We tested the hypothesis that nitrate exports in stream water are positively related to the N dynamics in foliar litter, with generally low exports during N immobilization and generally high exports during N mineralization in litter. We performed a simple regression analysis to test this hypothesis. We used litter N flux and nitrate export data for 2002-2006 from two watersheds at the Fernow Experimental Forest in West Virginia, one receiving ambient and one receiving experimentally increased rates of atmospheric deposition. Linear regression of monthly stream nitrate export values with litter N flux revealed no relationship. We conclude that while foliar litter immobilizes N, and the amount of immobilized N is of similar magnitude as that arriving with deposition, this N-retention mechanism does not translate into lowered nitrate exports in stream. Further, nitrate exports do not increase during the litter N mineralization phase.