Maples are an extremely common tree throughout New Jersey, on streets and in parks and forests. There are seven different species of maples native to the state, so you have plenty of options if you are looking to add a native maple tree to your yard. When selecting a maple, however, be careful! There’s one species that’s not only non-native, but is invasive! Norway Maples are hardy and have been frequently planted as street trees throughout the state, but they have a tendency to spread easily and crowd out other plants. Read on to find out everything wrong with Norway Maples, and how they came to New Jersey in the first place!
Norway Maples, as their name suggests, are native to Europe and Western Asia, but have become a prolific tree throughout many parts of the United States, including New Jersey. The tree was first brought to the states in the mid-1700’s and quickly became popular, often used as a shade tree alongs streets and in parks. The Norway Maple is tolerant of pollution and able to adapt to many soil types, making it ideal for modern urban areas. Unfortunately, the Norway Maple is invasive, and causes issues both in its immediate area and farther away as the seeds can spread aggressively. Still, many cities and homeowners continue to plant it, its adaptability to different conditions and fast growth rate making it a commonly planted street tree even today.
So what’s so bad about the Norway Maple? One of the biggest issues, especially for those planting in their yard, is the inability for many other plants to thrive under the canopy of a Norway Maple. While the tree definitely accomplishes its job as a shade tree, the canopy is often so dense and good at blocking sunlight that even shade-loving understory species have a difficult time establishing. Another factor influencing the growth of other plants is the Norway Maples’ shallow root system, which grows close to the surface and competes with other plants for resources. Even lawn grass and weeds can have difficulty surviving, although English Ivy – another invasive – is known to thrive under Norway Maples. The trees themselves are prone to root girdling, and the shallow roots have the potential to cause sidewalk conflicts when not given enough space as a street tree. This is quite ironic, given its popularity as a street tree!
The Norway Maples’ adaptability is also what has allowed it to become invasive in the United States. Seeds are spread by the wind, and are able to germinate even in heavy shade, with seedlings growing rapidly. When seeds begin to sprout in forested areas, they often go unnoticed for quite some time. Even as a young tree, their thick canopy and shallow roots prevent other native plants from establishing. This leads to forests with a poorly developed understory, with the only remedy being to remove the maples. The lack of predators in North America has also contributed to the Norway Maple’s status as invasive, with it being able to spread mostly unchecked. It is affected by some pests and fungi in this region, such as the fungi that causes verticillium wilt, but the impact is not large enough to significantly impact the Norway Maple population in the United States.
As Norway Maples were such popular trees, there is little that can be done to completely remove them from New Jersey’s ecosystem, short of removing each one. This is incredibly expensive and time-consuming, and the trees do provide shade (if sometimes a little too much!) and environmental benefits such as improving air quality and intercepting stormwater runoff. The most practical solution is to avoid planting any more, and remove seedlings as they sprout. Maples in general are lovely shade trees, so if you want one in your yard, don’t worry! There are plenty of species native to New Jersey that you can choose from – Sugar Maple, Black Maple, and Red Maple are some great options. If you plant a Sugar Maple, you can even get some syrup out of it! Help us stop the spread of invasives in New Jersey by researching tree species before purchasing, and choose native as much as possible.