Nutritional Quality of Douglas-Fir Wood: Effect of Vertical and Horizontal Position on Nutrient Levels

Timothy D. Schowalter, Jeffrey J. Morrell


The chemical composition of the boles of 14 Douglas-fir trees growing in the central Willamette Valley of western Oregon was examined to determine whether differences in various chemical component levels might help to explain arthropod or microbial colonization patterns. Levels of nearly all cations as well as N and P tended to be highest in the inner bark. Nitrogen levels were similar in sapwood and heartwood, but both were lower than those in the inner bark. Levels of N, P, Mg, Fe, and Zn tended to be significantly higher farther up the tree, suggesting that this zone might be a more suitable substrate of colonization. Water-soluble sugars tended to be present at higher levels closer to the live crown, a finding that implies that these compounds may be allocated to cells closer to the regions where active photosynthesis is occurring. Water-soluble sugars tended to be present at higher levels in the heartwood, an unexpected finding since these compounds are presumed to be consumed during heartwood formation. A broader sample of Douglas-fir boles is recommended to confirm these results.


Bark;chemical composition;Douglas-fir;heartwood;sapwood

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