Steven S. Perakis Alison Cross 2011 Old-growth forests of the Pacific Northwest provide a unique opportunity to examine tree species &ndash; soil relationships in ecosystems that have developed without significant human disturbance. We characterized foliage, forest floor, and mineral soil nutrients associated with four canopy tree species (Douglas-fir (<i>Pseudotsuga menziesii</i> (Mirbel) Franco), western hemlock (<i>Tsuga heterophylla</i> (Raf.) Sarg.), western redcedar (<i>Thuja plicata</i> Donn ex D. Don), and bigleaf maple (<i>Acer macrophyllum</i> Pursh)) in eight old-growth forests of the Oregon Coast Range. The greatest forest floor accumulations of C, N, P, Ca, Mg, and K occurred under Douglas-fir, primarily due to greater forest floor mass. In mineral soil, western hemlock exhibited significantly lower Ca concentration and sum of cations (Ca + Mg + K) than bigleaf maple, with intermediate values for Douglas-fir and western redcedar. Bigleaf maple explained most species-based differences in foliar nutrients, displaying high concentrations of N, P, Ca, Mg, and K. Foliar P and N:P variations largely reflected soil P variation across sites. The four tree species that we examined exhibited a number of individualistic effects on soil nutrient levels that contribute to biogeochemical heterogeneity in these ecosystems. Where fire suppression and long-term succession favor dominance by highly shade-tolerant western hemlock, our results suggest a potential for declines in both soil Ca availability and soil biogeochemical heterogeneity in old-growth forests. application/pdf 10.1139/X10-199 en Canadian Science Publishing Tree species and soil nutrient profiles in old-growth forests of the Oregon Coast Range article