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Weather and Tree Growth Associated with White Fir Mortality Caused by Fir Engraver and Roundheaded Fir Borer

Author: Craig D. Whitesell

Publisher:

Published: 1974

Total Pages: 182

ISBN-13:

Ohia forest decline-its severity and rate of spread-was studied by aerial photographic techniques on a 197,000-acre (80,000-ha) portion of the island of Hawaii. In 1954, only 300 acres (121 ha) showed signs of severe decline; by 1972, the acreage of severely affected forest had increased to 85,200 acres (34,480 ha). Rate of decline and current severity were related to mean annual precipitation and to elevation. The epidemic is continuing. Some forests on other Hawaiian islands also display decline symptoms.

Weather and Tree Growth Associated with White Fir Mortality Caused by Fir Engraver and Roundheaded Fir Borer

Author: George T. Ferrell

Publisher:

Published: 1975

Total Pages: 11

ISBN-13:

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Multivariate regression analysis was used to explore the relationship of weather and tree growth to the average volume of Abies concolor sawtimber killed annually by fir engraver (Scolylus ventralis Lec.) and roundheaded fir borer (Tetropiurn abietis Fall) beetles. Data for the years 1944 to 1954 from 22 plots in northern California showed that white fir mortality increased in years when (a) fir radial growth during the cunent and previous 2 years declined an average of 2.5 percent per year, (b) precipitation during the current and previous years averaged 11 percent below normal, or (c) spring precipitation averaged 32 percent below normal. Levels of mortality were related chiefly to regional fluctuations in radial growth of dominant and intermediate fir.