Radial Growth of Grand Fir and Douglas-Fir 10 Years After Defoliation by the Douglas-Fir Tussock Moth in the Blue Mountains Outbreak

摘要

Radial growth recovery related to amount of tree defoliation was measured 10 years after a severe outbreak of Douglas-fir tussock moth (Orgyia pseudotsugata (McDunnough). For the period 1978-82, growth of grand fir surpassed and was significantly greater than in the pre-outbreak period, 1968-72. Douglas-fir growth during the post-outbreak period showed similar patterns, but it was not significantly different from pre-outbreak growth for every defoliation class. Growth of undefoliated trees was also greater during the post-outbreak period, indicating that above-normal precipitation aided tree recovery and masked the thinning effect of tree mortality.