226 Illustrated Theatre Production Guide 2 ed
TREES AND WOOD
Softwoods are coniferous trees that have a needle-like
leaf structure. The most common varieties in North
America are pine, spruce, redwood, cedar, and fir. Fir,
pine, and spruce are the three types of wood most often
used to produce lumber. There are many different vari-
eties of pine trees, but they can be separated into two
main types, yellow and white. Stage scenery has tradi-
tionally been constructed of white pine. White pine is
an extremely workable wood for building scenery, as it
is soft and easy to cut, it has a straight grain pattern,
and it is widely available at a reasonable price. Yellow
pine is much heavier and is more susceptible to splitting.
Fir is quite often used to make interior trims and
moldings.
At least a cursory understanding of the mechanics
of how trees grow can help you understand how wood
will react when it is used for building stage scenery.
Because trees grow naturally, they are prone to quirks
that cannot be entirely eliminated by the lumber milling
process.
Many people seem to think that trees grow upward
out of the ground, but this is not the case. In reality,
they grow from the top up and from the outside out,
and not from the center or bottom. Tree bark protects
an interior layer of fibers known as the cambium or
sapwood. The cambium layer of a tree is the area where
growth rings originate. Everyone has seen growth rings,
which are evident when looking at a cross section of a
tree trunk. These rings are added to from the outside,
which is to say that each year’s growth ring, provided
by the cambium layer, is added to the outside of the
tree trunk, just under the bark. Bark is very much like
skin for a tree and protects the cambium layer from
weather and disease. Bark is rough because it must con-
stantly expand as the tree grows.
The cambium is responsible for transporting water
and nutrients from the ground to the leaves. It is really
a mass of tiny tubes much like blood vessels. These
fibers are very strong and pliable along their length, but
they are not bound together all that well. It is possible
to strip the fibers from some trees into long strings. This
works with other plants as well. Hemp fibers are stripped
from the stalk of that plant and then twisted into rope.
You may think of a stalk of celery as being indicative of
the mechanics of the structure of a tree. The stalk will
bend along its length, but will easily snap across its
width. After it does, the stringy fibers that make up the
stalk are plainly visible.
Celery grows to its full size in one season, so there
is no division of growth rings. A tree can grow over
hundreds of seasons, and the heartwood, or interior of
the trunk, is the remaining evidence of many years
cambium layers. The heartwood is the rigid material
that gives the tree its strength and ability to remain
erect.
The way a tree grows means that objects on the
outside of the tree trunk will eventually be enveloped
by it. If a sign is nailed to the exterior of a tree trunk,
some years later the tree will have grown around it,
causing the sign to eventually disappear. The same thing
can happen to wire fences and other manmade objects
in the forest.

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