How long is tree growth and forest growth affected by an outbreak?

Tree growth is affected as long as defoliation continues, usually 8-10 years. If the tree survives, growth begins to recover soon after defoliation ceases and is back to normal about 5 years later. The effects on forest growth are much longer lasting because of the loss of productivity in forest stands killed or salvage harvested during the outbreak. Wood supply projections for New Brunswick are counting on major increases in wood supply in about 2040 and 2060, the result of silviculture investments. A severe spruce budworm outbreak without foliage protection has been projected to reduce wood supply by 25 percent for 10 years after the beginning of the outbreak and to remain below expected levels for over 40 years.


Hennigar, C.R, Erdle, T.A, Gullison, J.J, MacLean, D.A. 2013. Reexamining wood supply in light of future spruce budworm outbreaks: a case study in New Brunswick. For. Chron.  In The Forestry Chronicle, 2013, 89(1): 42-53.

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