Site Index, Growth, and Foliar Chemical Composition Relationships in Western Hemlock
Abstract:Site index, growth, and foliar contents of the essential macro- and microelements, Al, and the chlorophylls of 20- to 30-year-old western hemlock (Tsuga heterophylla) trees were examined during the winter in eight natural stands in both the coastal and Cascade zones of western Washington and northwest Oregon. Site index at 50 years ranged from 22 to 39 m. Terminal growth and needle concentrations of most nutrients and the chlorophylls varied among the eight sites and the two zones. Site index was correlated positively with terminal growth, total N, chlorophyll 'a', total chlorophyll, and Fe, and negatively with Mn and sulfate-S. Also, total N was correlated with both chlorophyll 'a' and total chlorophyll. Results suggest that lower foliar concentrations of some important nutrients on some coastal sites may be factors in the reported general lack of success with N fertilizers in the coastal hemlock forests. Site productivity for western hemlock may be improved by cultural treatments that would enhance N, chlorophyll, and Fe contents of the needles. Levels of one or more of these components may be useful as indicators to assess site quality for hemlock production. In addition, chlorophyll may be used as a simple means to estimate N status of hemlock trees. Forest Sci. 26:283-290.
Document Type: Journal Article
Affiliations: Principal Silviculturist Pacific Northwest Forest and Range Experiment Station, USDA Forest Service, Olympia, WA 98502
Publication date: June 1, 1980
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