FRDA Report: Black Cottonwood and Balsam Poplar Managers ...

Information Sources:
Klinka and Feller 1984;
Farmer 1990; McLennan
1990; Winship 1990;
McLennan and Mamias
1992; McAuliffe 1993;
Silviculture Interpretations
Working Group
1993; Klinka et al. 1994.
Fortunately, because the value of cottonwood is increasing, managers may be able to
justify such costs more readily. On the positive side, planting whips permits final spacing
to be carefully controlled, which means that plantations can be established to meet
spacing objectives for specific end products such as pulp logs or veneer. Under the
medium-rotation extensive culture system practiced by Scott Paper Limited, experience
has shown that no site preparation or stand tending is needed.
In the case of balsam poplar, new reproduction can occur in several ways: from
new stems originating from intact or broken roots; from preformed or adventitious
buds on stumps or at the base of trees; and from buried stems and branches. Segments
of stems of all sizes buried during logging can contribute to regeneration. For balsam
poplar, this capability offers little reason for planting except in particular circumstances,
and even then its capabilities are an advantage because, unlike aspen, it will readily
reproduce by unrooted stem cuttings. Clonal differences are a major source of variation
in rooting percentage and the number of primary roots produced by dormant cuttings.
Stem cuttings have been the main means of stand establishment for short-rotation
intensive culture of balsam poplar elsewhere, especially in the Lake States. In situations
where special circumstances may make it desirable to plant balsam poplar, there are
good opportunities for genetic improvement of yield, partly because this species has
characteristics that facilitate breeding, and because of the ease with which it can be
propagated by stem cuttings.
Stump sprouts breaking off at the stump, especially from taller stumps, have often
been observed. This suggests the need for better guidelines on preferred stump heights
for optimum sprout production.
In many instances, natural regeneration of cottonwood and balsam poplar is from
both seed and vegetative sources. An advantage of natural regeneration is the cost
factor; a major drawback is unevenness of spacing, which results in less than full site
utilization. Vegetative sprouts initially grow more rapidly than seedlings and will shade
out slower-growing individuals. Planting that uses wildling whips or nursery stock with
controlled spacing offers an alternative if local stock adapted to local growing conditions
is used. Planting also gives the forest manager the potential for manipulating stands to
enhance wildlife forage or habitat. After whip planting, stand tending is usually not
necessary except for fill planting. However, the choice of whip planting requires a
commitment to special care. Whips need to be carefully handled and properly stored
so that they are not desiccated at time of planting. As well, their buds must not be
flushed at planting time. Even with these precautions, some mortality of whips should
be expected.
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