Influences of wood decomposition on nitrogen (N) dynamics were investigated in six western Oregon streams. Wood substrates of high and low nutritional quality (indexed by C:N, lignin:N, and total lignin content) were incubated in each stream for one month during the summers of 2004 or 2005. Total dissolved N (TDN) concentrations ranged from 98 to 356 µg L^-1. Wood substrates also were incubated for six months in an old-growth coniferous forest stream during which half of the replicates experienced ambient conditions (TDN < 100 µg L^-1) while half were exposed to ~50 mg N d^-1. Preliminary results show that metabolic activity of wood biofilms (measured by respiration and enzyme activity) was higher on high quality wood than on low quality wood. Difference between respiration rates on the two substrate types increased 19 – 111% with higher TDN concentrations, indicating that greater amounts of carbon and N were released from high quality wood when exposed to elevated N concentrations. Results from stable isotope tracer (¹⁵N) studies conducted in both experiments also will be presented. Overall, these experiments indicate that wood decomposition in streams can play a significant role in maintaining the natural range of N export from forested landscapes.