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Title: Role of acid and aluminum-rich media in the growth and nutrition of Pacific Northwest conifers

Thesis/Dissertation ·
OSTI ID:6018414

Forest soils of coastal Washington and Oregon tend to be very acidic with large accumulations of organic matter. Yet the productivity of forest species on these sites can attain record levels. The effect of acid and aluminum-rich media on the growth and nutrition of Pacific Northwest conifer species was investigated for western hemlock, Douglas-fir, western redcedar, and Sitka spruce. The four different types of growth media utilized were solution cultures, sand cultures, mineral soils, and forest floor organic matter. Hydroponic nutrient solutions and sand cultures were used in experiments designed to differentiate the effect of aluminum ions from the hydrogen ions generated by hydrolysis of Al/sup 3 +/. Relative to agronomic plants, all the conifers were found tolerant of the acid solutions and high levels of aluminum. Species differed in their relative tolerance to H/sup +/ and Al/sup 3/ ions. Western hemlock seedling growth was superior to Douglas-fir in the acidified soils and forest floor media, while Ca(OH)/sub 2/ amendment favored Douglas-fir. The marginal increase in western hemlock growth in N + P treated soils was highest in acidified soils. Western hemlock exhibited an ability to absorb nutrients in the presence of excess solution H/sup +/ ions, maintain growth with low tissue requirements of Ca and Mg, and accumulate high levels of aluminum in its roots and foliage without major adverse effect. These attributes are considered to make western hemlock the most acid and Al-tolerant of the four Pacific Northwest forest species studied. Western redcedar was second in acid tolerance to western hemlock. This species' ability to accumulate Ca minimized Al absorption and H/sup +/ damage to its roots.

OSTI ID:
6018414
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English