A silvicultural experiment to mitigate pest damage

An optimal impact design experiment was established in 1997 to investigate silvicultural alternatives for reducing vulnerability of white spruce (Picea glauca (Moench) Voss) stands to spruce budworm (Choristoneura fumiferana (Clem.)) damage. Ecosystem and insect population responses are being assessed in stands, thinned using a cut-to-length harvest system that removed 25% or 50% of standing volume in three patterns: uniform shelterwood cuts, standard strip cuts, and strips with "feathered" edges. Clear-cuts and untreated checks support comparisons among the undisturbed state, conventional practice, and thinning regimes. Subplots in the uniform shelterwood cuts and untreated checks were fertilized with 200 kg N/ha in early spring of 1998. The experimental approach permits strong inferences to be made about treatment effects but requires several years to obtain the final results from the research program. Keywords: spruce budworm, thinning, project design