Document Type

Review

Publication Title

Maine Woodlands

Publisher

Maine Woodland Owners

Publication Date

Summer 7-2025

Publisher location

Augusta, Maine

Issue Number

7

Volume Number

50

Abstract/ Summary

This review challenges a long-held axiom in silviculture that stand density does not affect the height growth of dominant and codominant trees. Contrary to a widespread myth, which mistakenly asserts that crowding makes trees grow taller, evidence from spacing studies consistently demonstrates that trees grown at wider spacings achieve greater height growth. For instance, a 43-year study on Douglas-fir showed dominant trees in the widest spacing were nearly 20 feet taller than those in the narrowest, alongside having larger crowns. This enhanced growth is linked to maintaining a sufficient live crown ratio (at least 45-50%), which crowded stands inhibit. The misconception about density's effect on height growth also impacts site quality estimation, leading to significant differences in estimated site index for trees on identical soils. Therefore, while textbook generalizations suggest otherwise, the effect of crowding on height growth is negative. Consequently, silvicultural practices like thinning and crop tree release, which reduce competition, are shown to enhance height growth over a feasible range of densities.

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