Tree growth in thinned and unthinned White fir stands 20 years after a Douglas-fir tussock moth outbreak.

Abstract

Twenty-year postoutbreak growth was compared in thinned and unthinned, severely defoliated stands. Basal area of unthinned white fir has declined 37 percent and pine basal area has increased 32 percent since 1964. The stand thinned in 1960 has the lowest basal area in the study area, but the greatest tree growth before and after the outbreak. All defoliated fir are growing significantly faster during the 16 years after the outbreak compared to before the outbreak. Thinned stands, even though not resistant to defoliation, may be able to recover more rapidly and to a much greater magnitude than unthinned stands after an outbreak.

Citation

Wickman, Boyd E. 1988. Tree growth in thinned and unthinned White fir stands 20 years after a Douglas-fir tussock moth outbreak. Res. Note PNW-RN-477. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 12 p.