Knowing Our Maples

May 8, 2018

Sugar Maple Tree
Credit Kyle Lawrence / Wikimedia Commons

In this month's installment of Field Notes Scott Bowe of Kemp Station discusses Wisconsin’s maples and how they are used in homes and schools.

Wisconsin has seven native maple trees and many more non-native ornamental maples, with some of these considered invasive. We all know the sugar maple, our state tree, but the others are less well known. Let’s look at Wisconsin’s maples and how they are used in our daily lives.

I’ve already mentioned sugar maple, Acer saccharum. Our state tree and most abundant tree species by volume in all of Wisconsin, boasting 2.8 billion cubic feet in live trees. Sugar maple is popular in sugar bushes around the state. It’s not the only maple that can be tapped for maple syrup production, but it does have the highest sap sugar content of our native maples. From a production perspective, sugar maple is called hard maple in the hardwood lumber industry. It is hard and dense, equal to red oak in density. Hard maple has a diffuse porous cell structure, which means the cell diameters are relatively small, which produces a closed and subtle grain pattern. Hard maple has been popular for years for kitchen cabinets and in solid strip wood flooring, especially sports flooring applications.

Red maple, Acer rubrum, is the second most abundant tree species by volume in all of Wisconsin with 2.7 billion cubic feet of live trees. Red maple can also be used for maple syrup production, but its sap sugar content is less than sugar maple. In the sawmill industry, red maple is called soft maple. Despite its name, soft maple is still relatively hard and dense, but less dense than sugar maple. Soft maple has a diffuse porous cell structure like hard maple and looks very similar in appearance.
Soft maple is a less expensive substitute for hard maple lumber and is also used for kitchen cabinets usually in painted applications. Both hard and soft maple are important pulpwood species supplying our pulp and paper industry.

Silver maple, Acer saccharinum, is a maple species that likes to keep its feet wet. Growing in creek bottoms and wet areas, it is fast growing and less dense than sugar or red maple. Silver maple is grouped into the soft maple lumber group by the sawmill industry. Silver maple lumber is similar in appearance to red maple, but cannot be used interchangeably. If you were to glue up a solid door panel with a mixture of red and silver maple staves, you would see a clear difference. Especially when the door panel is stained, the staves will not match.

Boxelder, Acer negundo, is sometimes called boxelder maple or Manitoba maple by our friends to the north. It is often thought to be another species because it has a compound leaf with three leaflets. Not considered a commercial species, it is common flood plains and other disturbed areas. Fast growing, it will pop up along fence lines and alley ways. If you want a fast-growing tree in your yard, plant a boxelder. If you want two trees, cut a branch and stick it in the ground, it will grow. Even though boxelder is not a commercial lumber species, its wood can have a pinkish color, which makes for interesting paneling.

The last three native maples are less well known. They are striped maple, Acer pensylvanicum, mountain maple, Acer spicatum, and finally black maple, Acer nigrum, which some people believe to be a subspecies of sugar maple.

Norway maple, Acer platanoides, is very common in Wisconsin, but it is an exotic species brought over from Europe in the 1700s. It became a popular yard tree and street tree because of its dense foliage, ease of transplanting, and fast growth rate. Norway maple is well suited to the urban environment because it tolerates road salt, concrete, and a variety of soil types. Norway maple was a popular replacement for the American elm after the wave of Dutch elm disease. Norway maple is not a commercial lumber species and is considered an exotic invasive since it has made its way into native forests throughout the eastern US.

There are more than a dozen ornamental maples that can survive Wisconsin winters. These varieties were bred for size, shape, and color for ornamental design applications. Many are exotic and considered invasive but make up a large part of our urban landscape. They go by names such as Amur Maple, Autumn Blaze, Indian Summer, Crimson King, Japanese Maple, and many more.

From a wildlife perspective, maples are important nesting trees for birds and small mammals. The flowers are an important food source for pollinating insects, while the seed mast is an important food source for small mammals and birds.

Maples make up a large part of our forests with sugar and red maple being the two most abundant species in Wisconsin. Both are important lumber and pulpwood species. Wisconsin supports dozens of other maples that make our state a great place to live and work.

For Field Notes, this is Scott Bowe from the University of Wisconsin-Madison’s Kemp Natural Resources Station.