Since autumn and the inevitable falling of leaves is upon us, a great
opportunity presents itself in disposing of a major infestation of
non-native, exotic invasives. Usually I'm not so empassioned about
gardening or plant wildlife in general, but with this topic I make an
I am talking about the Norway maple, acer platanoides. Usually it is
extremely difficult to remove this import from Europe and Asia. In
fact, many nurseries still sell these trees, a practice which should
be outright banned in all states, punishable by severe fines. The
major problem with destroying any maple one finds is that native
maples, especially sugar maples, could easy be mistaken for the
The good news is there are several ways to tell the two apart. One is
the Norway's dense growth in extremely shady areas. Norways also
excrete a miky sap when a leaf stem is torn off the branch, whereas a
sugar maple's sap is clear.
However, the easiest way to tell the two apart is in the fall, when
the leaves change color. The native sugar maple will have at least
some tinge of red in their leaves. Usually they are all-red, but may
contain some flecks of gold or brown. The non-native norway maple
leaf will be completely golden-yellow or brown, and their leaves
usually fall several weeks after sugar maples are done with their
leaves. If you see an all-yellow maple tree in the woods late in the
plumage season, it's almost certainly a Norway maple and should be
destroyed. If it cannot be immediately destroyed then make a mark on
the trunk (ie hatchet chop, lean a rock on the side, etc.) so it can
be dealt with later.
Why am I so emphatic about destroying this tree? Because it is an
"exotic invasive", meaning it is not only alien to our woodlands, but
it ultimately out-competes native trees and undergrowth, destroying
the bio-diversity of our woodlands and the ability of native wildlife
to exist in those areas. The Norway maple produces enormous clumps of
leaves, shading everything underneath them with an intolerable amount
of darkness, something native plants cannot compete against. Berry
bushes that would've supported native wildlife are stifled, since they
never had the oppotunity to evolve and compete with such competition.
The Norway also grows faster than nearly any other deciduous tree in
North America; many have been reported to grow 4 FEET per year. The
Norway also keeps its leaves longer than native plants; it is almost
always the first tree to sprout in spring, and the last to lose its
leaves in autumn. To add the ultimate insult to injury, the Norway
maple excretes a mild but toxic substance into the soil around its
roots, adding the finishing touch in preventing any other plant, other
Norways excluded, from surviving underneath its dense canopy. It also
seeds profusely; a single tree can spread thousands of seeds and
seedlings across the landscape every year. Since the seedlings can
tolerate dense shade, they grow quickly under any tree canopy. The
Norway's sugar content does not even exist; it produces a milky sap
that is un-suitable for sugar production, thus making it a direct
threat to the American maple syrup industry.
The only sure way to remove a maple tree is to saw at the base, then
"paint" the trunk base with a strong application of herblicide.
However, too much to the surrounding area may damage other nearby
plants. Without the herbicide application, the trunk will sprout
dozens of new shoots. Within a year these shoots could easily reach 3
feet tall or more. Even lone trees, miles from any forest can pose a
threat; a bird could digest the seed and carry it hundreds of miles on
a migratory route, so removing as many as possible is helpful. Even
without wildlife assistance the seeds are designed to float on the
wind like a tiny sailboard; the seed could ultimately land several
hundred feet from its original mother tree.
If a norway maple is being kept for shade or fall color, there are
many, MANY native alternatives to growing this exotic, un-American
tree. The tulip, or yellow poplar is a fast grower, and can provide
equivalent shade and color conditions as the norway, but there are
many other planting alternatives, including a native sugar maple.
This tree is a very significant danger in the northeast US and Canada.
It is akin to brambles in the pacific nothwest, or kudzu in the deep
south. Without assistance these trees will continue to spread and
slowly wipe out wildlife and especially bio-diversity in our forests.