Effects of gypsy moth defoliation on softwood and hardwood growth and mortality in New Brunswick, Canada

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作者
Hennigar, Chris Richard [1 ]
MacLean, David A. [1 ]
Norfolk, Chris James [2 ]
机构
[1] Faculty of Forestry and Environmental Management, University of New Brunswick, Fredericton, NB E3B 5A3, Canada
[2] New Brunswick Department of Natural Resources, Forest Management Branch, Fredericton, NB E3B 5H1, Canada
来源
Northern Journal of Applied Forestry | 2007年 / 24卷 / 02期
关键词
The first major European gypsy moth (Lymanlrio dispar L.) outbreak occurred in central New Brunswick, Canada, on over 3,000 ha of forestland, from 2001-2003. The outbreak was severe enough to result in considerable landowner concern and a privately funded aerial insecticide spray program to protect trees. Defoliation was unexpectedly severe on several tree species thought to be resistant or immune, as indicated from studies in the northeastern United States. Fifty plots (564 trees) were established and measured for standard mensurational characteristics, defoliation, and annual tree mortality, and after the cessation of defoliation, 44 trees were destructively stem analyzed to determine growth patterns. Balsam fir (Abies balsamea [L.] Mill.) with defoliation of more than 75% sustained specific volume increment reduction averaging 55% and 25% mortality after 2 years of severe defoliation. Red oak (Quercus rubra L.) sustained about 40% growth reduction, similar to results of previous studies. However, white birch (Betula papyrifera Marsh.) and trembling aspen (Populus tremuloides Michx.), with more than 75% defoliation for 2 years, sustained 43-48% growth reduction, higher than in previous studies, and 4-12% mortality. The gypsy moth range in Canada appears to be gradually expanding beyond previous climatic (cold winter temperature) limitations, and these results will help to predict future impacts. Copyright © 2007 by the Society of American Foresters;
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页码:138 / 145
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