Correcting stem deformities in juvenile planted white spruce

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SILVICULTURE AND RESEARCH SECTION, NEWFOUNDLAND FOREST SERVICE
P.O. BOX 2006, CORNER BROOK, NEWFOUNDLAND, A2H 6J8
_ ; No. 56, February, 2001
FOREST RENEWAL /FOREST IMPROVEMENT NURSERIES TREE IMPROVEMENT MISC.
CORRECTING STEM DEFECTS IN
JUVENILE PLANTED WHITE SPRUCE:
SECOND YEAR RESULTS
by
Basil English, Research Silviculturist
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"AND IN CONCLUSION..."
• Birds, insects, frost, etc., frequentlydamage the
terminal leaders and buds of juvenile white
spruce. As a result, multileadering and forking
are common in young plantations of this
species. The question was asked: is thereany
benefit in intervening to correct these defects?
• In 1998, a trial was established to assess the
responseof juvenileplanted whitesprucewith
stem defects, to form correction. The trial was
assessed in the fall of 2000, after two growing
seasons.
• Preliminary resultsindicate thatinterventionto
correct multileadering and/orstem forking had
a positive impact. For both defect types, the
corrected trees were much more likely to be
well formed after two years than the
uncorrected trees.
• Trees with multiple leaders had a far higher
rate of natural recovery to well formed status
than those with forks: 47% of the former
recovered without intervention ascompared to
only 20% of the latter.
• After two years, almost a third of the control
trees (i.e., trees that were well formed at the
start of the trial) had developed defects. As
well, approximately the same proportion of
deformed/corrected trees had developed new
defects. This pattern, coupled with the
relatively high rate of natural recovery,
suggests that intervention to correct stem
defects is likely not worthwhile in planted
white spruce.
INTRODUCTION
Defects, such as muItileaders and forks, are
very common in young white spruce
plantations in Newfoundland. Such
problems typically arise following the loss
of the terminal leader or bud to a damage
agent such as frost, insects, birds,
mammals, etc. It has been suggested that
plantation maintenance activities (e.g.,
cleaning out of ingrowth) could be
expanded to include the correction of such
defects. The question is, would such an
intervention have any lasting benefit?
Would the affected trees outgrow the
problem without intervention? Is there any
guarantee that a new defect would not
develop once the existing one was
NEWFOUNDLAND FOREST SERVICE

corrected? Would those trees that are
currently free of defects remain well
formed into the future?
In the fall of 1998 a trial was set up to
determine whether or not there is anything
to be gained by manually correcting
multileadering and forkingdefects in young
planted white spruce. The following is a
status report on the defect correction trial,
two years post establishment.
METHODS
Forthe purposes of this trial, multileadering
refers to a situation in which the tree's
current leader or bud is missing, dead or
damaged, and two or more lateral shoots
are competing for crown dominance.
Forking refers to a situation in which
multileadering last year, or in some
previous year, has resulted in the
development of two separate and
competing tops. Generally, multileadering
gives rise to forking. In this study, trees that
fork at or below ground level are not
considered to be forked.
The trial was incorporated into two small
plantations, both of them active research
trials being maintained and monitored by
the Silviculture and Research Section of the
Newfoundland Forest Service. The first trial
site is located on Corner Brook Pulp and
Paper Ltd. (CBPPL) licensed land at Bottom
Brook in Forest Management District (FMD)
14, approximately 25 km due east of
Stephenville. This planting trial was
established in the spring of 1993 with 67-
multipot container and 2 + 2 bareroot white
spruce seedlings. The objective was to
investigate seedling growth response to
various planting technique/site preparation
options. In the fall of 2000 the plantation
was eight years old.
The second trial site is located on CBPPL
licensed land at South Branch in FMD 14,
approximately 6 km northeast of the
community of Coal Brook. This planting
trial was established in the spring of 1992
to assess the response of 67-multipot
container white spruce to various root
system management regimes. In the fall of
2000 this plantation was nine years old.
At each site, assessors flagged all forked
and multileadered trees. Half the trees of
each defect type were corrected with
pruning shears. That is, shears were used to
remove all but the strongest leader (in the
case of multileadered trees) or all but the
strongest top (in the case of forked trees).
The remaining trees were left uncorrected.
Additionally, naturally well formed trees
were selected as controls. As described in
Table 1, this resulted in the creation of five
stem form categories. Every attempt was
made to balance the selections so that the
trees in each of the five form classes came
from comparable situations. In total, 538
trees are represented in the trial.
The heights of all sample trees were
measured at the time of trial establishment.
and again in the fall of 2000. As well,
during the fall 2000 assessment, the stem
form
status of each tree was evaluated.
NEWFOUNDLAND FOREST SERVICE