Individual tree five-year basil area and crown diameter growth in Applachian hardwood stands as influenced by thinning and gypsy moth defoliation
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I evaluated silvicultural treatments to minimize gypsy moth effects on forests in experimental plots on the West Virginia University Forest. Two treatments, presalvage thinning and sanitation thinning, were used. As part of the evaluation, I measured individual tree basal area growth and crown diameter growth over a five-year period. This period began with pretreatment measurements of stem dbh and crown diameter in 1989 before thinning and defoliation. Thinnings were installed during the winter of 1989-1990 and had paired control stands that were not thinned with four replicates of each treatment and control. Gypsy moth defoliated six of the 16 stands in 1990 and 1991. Mortality resulting from the defoliation-induced stress along with drought stress in 1991 occurred over the following three years. At the end of this period of stress and mortality, stem dbh and crown diameter were remeasured for all living trees. Stem dbh was converted to basal area. Basal area growth and crown diameter growth (or shrinkage in some cases) were calculated by taking the difference between the two measures.