Red Maple: An Early Source of Nectar and Pollen

Introduction

Red maple (Acer rubrum) is a medium height tree that can grow up to 100 feet tall. It is native to most states in the eastern half of the U.S. and much of eastern Canada. Red maple is one of our earliest blooming native trees and can be an important food source for a variety of pollinators and wildlife. However, over the past century or so, it has become increasingly more common in our forests, which is creating potential ecological complications that are only beginning to be recognized.

Red Maple General Biology and Life History

Red maples are currently one of our most common and abundant tree species in eastern North America. They are highly adaptable and can grow in a wide variety of soils, climates, and other conditions. The red maple gets its name from the color of its petiole (leaf stem), flowers, seeds, and often its fall foliage. (Red maple leaves can also turn yellow or orange, instead of red, during the fall. This trait appears to be genetic with regional genetic differences making the brilliant red fall foliage more common in the North.)

They are one of our first native trees to bloom in the late winter or early spring. The flowers appear before the leaves and are relatively small. They bloom earlier in the warmer, more southern regions of their range, and later in the cooler, more northern regions of their range. For reference, in Kentucky the red maple bloom typically happens sometime between mid-February and mid-March. An individual tree may have all male flowers, all female flowers, or a combination of male flowers on some branches and female flowers on other branches.

After the female flowers have been pollinated, clusters of paired, reddish seeds called samara appear. The clusters of immature samaras are more conspicuous than the earlier flowers and are often mistaken for flowers. The mature samaras are dispersed by the wind. As a samara falls to the ground, it will often spin with a characteristic pattern reminiscent of the slowly spinning blades of a helicopter. The seeds sprout soon after falling to the ground and a red maple seedling can be several inches tall by the end of its first fall and may grow several feet each year for the next several years.

Because red maples are so adaptable, so easily dispersed by the wind, and grow so rapidly, they are often one of the first deciduous trees to colonize an open area. In the distant past, natural fires and fires set by Native Americans kept red maples from colonizing and overtaking grasslands or other more open habitats. (Red maples are highly sensitive to and easily killed by fire.) Once fire was removed as a frequent component of the landscape, red maples quickly began taking over many formerly open areas. They were also quick to colonize and take over after many older forests were cleared. Although they are early colonizers of open land, their seedlings are also relatively shade tolerant and can grow even under dense stands of older red maples.

Potential Ecological Complications

Red maples are much more common in our forests today than they were several hundred years ago. In most truly old-growth forests, they represent a relatively small percentage of the trees found in the forest. However, in younger forests – everything from relatively recently abandoned fields to forests that may be over a hundred years old – they are frequently a major component and, in some cases, the dominant component of the mature canopy trees. Despite their important uses for wildlife and pollinators, that isn’t a good thing.

The problem is that when red maple numbers are significantly out of proportion with what their numbers historically were or they are growing in areas that were historically grasslands, then you end up with a less diverse ecosystem. For example, areas that have dense stands of red maples can shade out and prevent other more sun-loving saplings like those of oaks and hickories to grow. In most cases in the eastern U.S., more diverse natural ecosystems are also healthier. An over-abundance of red maples can reduce diversity, and therefore, the overall health of that ecosystem. If you own land that has a high percentage of red maples growing in the woods, then you may want to consider having a forester come look at the property and make recommendations on ways to manage your woods.

Pollinator and Wildlife Uses of Red Maple

Our early pollinators, including honey bees, bumble bees, cellophane bees, mining bees, and sweat bees will gather nectar and pollen from the flowers. The foliage is eaten by several species of moth caterpillars including many of our larger moths like the cecropia moth and rosy maple moth, as well as a number of smaller moths belonging to the inchworm family. Deer will also frequently browse the young twigs and leaves. The seeds are eaten by squirrels, small rodents, and songbirds. Birds, squirrels, and other animals will also seek shelter among the tree’s branches and in any hollows that might form in the trunk or branches.

Incorporating Red Maple into Your Yard

Red maple’s ability to adapt to a wide variety of conditions and its beautiful fall foliage make it a common species for use in landscaping. Its widespread use as an ornamental tree makes red maples very easy to find in the horticulture trade. Although as a general rule I tend to prefer straight species and local genotypes, when possible, there are lots of different cultivars available as well. Some of the cultivars have been specifically selected for their bright red fall foliage.

Red maples can be somewhat weedy if you have open ground (such as a garden bed) nearby; however, the young seedlings are very easy to pull up when they first sprout. Be careful when doing yard work around the tree, because red maples are relatively thin-barked and can be easily damaged if hit by a weed-eater or lawnmower. I commonly see maple trees in yards that are hollow or diseased because they were injured by a lawnmower or weed-eater. Many of these trees end up having to be removed due to safety concerns.

Summary

The red maple is an interesting native tree that is beneficial to pollinators and wildlife. It can also make a great landscaping tree. However, an over-abundance of red maples in a forest setting or taking over a grassland can reduce bio-diversity and cause its own set of issues. Like with many things, it is possible to have too much of a good thing and it is important to find and maintain the correct balance.