Research Branch Staff Publications

Pruning Density and Severity in Coastal Western Hemlock: 4-Year Results.

Citation:

de Montigny, L., and S. Stearns-Smith. 2001. Pruning Density and Severity in Coastal Western Hemlock: 4-Year Results. B.C. Min. For., Res. Br., Victoria, B.C. Ext. Note 51. 6 p.

Abstract:

Pruning density is the relative number of trees pruned; pruning severity is the amount of live crown removed. Pruning density and severity experiments were installed in two coastal western hemlock (Tsuga heterophylla [Raf.] Sarg.) plantations, 12 and 13 years old, on Vancouver Island. The pruning density experiment indicated that a single 3-m pruning lift significantly reduced 4-year average diameter by 1.3 cm and height by 0.5 m, regardless of whether all or half the trees were pruned on a plot. Treatments in the pruning severity experiments reflected a range of residual crown lengths: 1.5, 2.5, 3.5, and 4.5 m, plus no pruning (control). After 4 years, there were obvious downward trends in both average diameter and height with increasing pruning severity. Significant growth reduction appeared below a threshold of about 50% retained crown ratio. The most severe pruning treatment (1.5 m) reduced 4-year average diameter by 4.3 cm and height by 1.5 m, compared with the control.

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