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This study examined changes in stream and soil water NO3−and their relationship to temporal and spatial patterns of NO3−in soil solution of watersheds at the Fernow Experimental Forest, West Virginia. Following tenfold increases in stream NO3−concentrations over a 13-year period (1969–1981) on untreated WS4, concentrations have declined through 2006. Followingfourfold increases in stream NO3−on treatment WS3 from pretreatment levels to a 1998 maximum, concentrations have declinedthrough 2006, despite additions of N. Concentrations of soil water NO3−were consistently lower for WS4 compared to WS3.Data for soil water NO3−on WS3 versus WS4 followed patterns of net mineralization and nitrification for these watersheds.Nitrogen additions to WS3 decreased spatial heterogeneity of N processing, which was largest in the pretreatment year anddecreased significantly to a minimum by 2000-2001. Concurrently, soil water NO3−increased on WS3 from 1.3 mg NO3−-N L−1inpretreatment 1989 to a maximum of 6.4 mg NO3−-N L−1in 2001. Spatial heterogeneity in soil water NO3−on WS4 remained highduring this period. Data suggest that temporal patterns of stream NO3−may be influenced by spatial heterogeneity of watershedprocesses which vary over time in response to N availability.


The copy of record is available from the publisher at Copyright © 2011 F. S. Gilliam and M. B. Adams. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.