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Pruning trial with sugi ( Cryptomeria japonica ).
Authors: A. J. DakinPublication: New Zealand Journal of Forestry, Volume N.Z.J.For. 1982, Issue N.Z.J.For. 27(1) 1982, pp 89-100, May 1982
Publisher: New Zealand Institute of Forestry
Abstract: A trial is described which was designed to study the effects of pruning (green foliage removal) on growth of five-year-old Sugi.
At pruning, stand height averaged 4.5 m and diameter (b.h.) 8.3 cm. Stand density was 1850 stems/ha and green crown extended to within 0.3 m of forest floor.
Three levels of pruning were applied:
(a) Pruned to 1.2 m height on stem — a 40% removal of green crown.
(b) 1.8 m — a 60% removal.
(c) 2.4 m — a 76% removal.
The amount of foliage removed was based upon calculations of crown surface area.
Results show that all pruning treatments depressed diameter and height growth over a four-year period. Basal area losses over the period were 6% for (a), 17% for (b), and 23% for (c), when compared with unpruned trees.
It is concluded that to avoid large growth losses 40-50% actual foliage removal be set as the upper limit at low pruning. This equates to 30-35% removal of lineal green crown. These findings generally concur with recent Japanese pruning studies.