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Michael Saunders, Purdue University, Dept. of Forestry and Natural Resources, msaunder@purdue.edu (Presenter)
Christopher Zellers, Purdue University, Department of Forestry and Natural Resources, zellers@purdue.edu

 

The high economic value of black walnut as a timber tree makes it especially suited to highly intensive plantation management. However, such systems result in rapid crown expansion, necessitating the inclusion of green pruning into cultural practices to facilitate good stem form and the production of high quality wood. Intensive pruning practices may yield improvements in both stem form and wood quality, but the resulting removal of leaf area may cause a decrease in growth rates, thus increasing rotation periods. In this study, we examine the two-year growth response of an eleven-year-old plantation of black walnut as affected by pruning intensity and timing. Pruning intensity treatments included the following: High intensity, in which all branches below 4.0 m high, as well as codominant branches (branches > 3 cm with strong branch angles) within the crown were removed; low intensity, where all branches below 2.5 m high were removed; and control. Pruning treatments were applied during either dormancy (late November to early March), leaf expansion (mid- to late June), or at maximum leaf area (late July to early August). Projected leaf area, for both pruned and retained branches, was estimated using allometric models developed in a parallel study, and impacts on growth (height and diameter) were then examined as a function of leaf area reduction.