Fig. 2. Nitrate concentration in subsurface soil (charcoal free Willow Creek soil, 89 yr since last fire) treated with 2 mL of a nutrient solution containing 1.5 mM (NH₄)₂SO₄ and 1 mM KH₂PO₄ in factorial combination with charcoal (1% w/w) and phenol-rich A. uva-ursi litter extract (45 g phenolic compounds kg^–1 soil) and incubated for 14 d. Error bars represent ± one standard error of the mean (n = 5). Bars with similar letters adjacent to them indicate a not significantly different at P < 0.05 as determined using a Tukey's multiple range test.