Tree species and soil nutrient profiles in old-growth forests of the Oregon Coast Range

Canadian Journal of Forest Research
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Abstract

Old-growth forests of the Pacific Northwest provide a unique opportunity to examine tree species – 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 (Pseudotsuga menziesii (Mirbel) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), western redcedar (Thuja plicata Donn ex D. Don), and bigleaf maple (Acer macrophyllum 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.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Tree species and soil nutrient profiles in old-growth forests of the Oregon Coast Range
Series title Canadian Journal of Forest Research
DOI 10.1139/X10-199
Volume 41
Issue 1
Year Published 2011
Language English
Publisher Canadian Science Publishing
Publisher location Ottawa, Ontario
Contributing office(s) Forest and Rangeland Ecosystem Science Center
Description 16 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Canadian Journal of Forest Research
First page 195
Last page 210
Country United States
State Oregon