Document Type

Article

Publication Title

Maine Woodlands

Publisher

Maine Woodland Owners

Publication Date

Summer 6-2020

Publisher location

Augusta, Maine

Issue Number

6, 9, 10

Volume Number

45

Abstract/ Summary

Growing high-quality, knot-free timber requires active silvicultural management to control branch shedding and crown recession. Early in a stand's development, dense stocking forces the base of the live crown upward through "light extinction," confining the knotty core to a small diameter. Ideally, foresters manage the live-crown ratio (LCR) to stay at approximately 40% until the crown base reaches 17 to 33 feet. Once this height is achieved, heavy thinning via crop-tree release is essential to halt further recession and accelerate diameter growth, which facilitates rapid wound occlusion.

While hardwoods typically shed dead branches naturally, conifers like white pine exhibit decay resistance, causing dead branches to persist as "black knots". In these instances, artificial pruning is necessary to ensure the production of clear wood. Research suggests that "close cuts" parallel to the trunk result in faster occlusion and smaller knotty cores compared to "natural target" pruning. Specialized manual tools, such as telescoping saws, are often preferred over motorized options to minimize bark damage. Successful management also requires safety precautions and timing interventions to avoid the bark-peeling season. Economically, pruning is most viable for species with high market premiums for clear (knot-free) wood, such as eastern white pine. However, landowners often struggle to capture this timber value without detailed records or vertical integration. Additionally, intensive corrective pruning can mitigate damage from white pine weevil attacks, further enhancing stem quality.

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