An investigation of western hemlock (Tsuga heterophylla(Raf.) Sarg.) on the Queen Charlotte Islands, British Columbia, has shown that decay losses in old-growth stands are appreciable, amounting to 13.9, 8.0, and 10.7 of the gross volume of Grades 1, 2, and 3 logs respectively. Total loss, including dead trees, amounted to 25.5 of the gross volume. Twenty-seven decay-producing fungi have been isolated. The most important of these areFomes pinicola(Sw.) Cke.,F.pini(Thore) Lloyd,F.annosus(Fr.) Cke., andPolyporus sulphureusBull. ex Fr.Echinodontium tinctoriumE. amp; E. apparently does not occur in the region. Scars provided the most frequent, and roots the most important, avenue of entrance for decay. The logs of 2318 western hemlock were analyzed in detail. Decay was found to increase progressively with diameter, age, and decreasing site quality. Maximum net periodic increment was reached between 350 and 400 years of age and between 35 and 40ensp;in. in diameter. Color of bark was found to provide an added indication of tree maturity. Understory trees were found to give a substantial yield of sound wood.
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