Courtesy: Charles Newlon

Norway maple, Acer plantanoides, is a native of Europe and is a fine, and a popular ornamental street tree in Wilmington and along the streets of many eastern United States communities.

Trouble is, when Norway maple trees grow near a native, deciduous eastern forest, the seeds are often blown, or are carried by mammals and birds, into the native forest. The vigorous Norway maple seeds sprout and grow and can outgrow the native species and eventually take over the native forest.

Norway maple seeds are large and give seedlings a quick start. Eventually the large leaves, aggressive fibrous root system, and chemical exudations slow the growth of other plants, enabling Norway maple to overwhelm other species. This encroachment, over many years, will change the entire native forest ecosystem to a non-native forest ecosystem.

The present forest ecosystem in Brandywine Park has a rich biological diversity. It is made up of countless interdependent plant and animal inhabitants, from soil microbes to the tallest eastern deciduous tree species, the tulip-poplar tree.

Brandywine Park is the largest example of a native eastern deciduous oak-hickory forest, surrounded by an urban area, between Philadelphia's Fairmount Park and Washington D.C.'s Rock Creek Park.

According to entomologist Dr. Douglas W. Tallamy of the University of Delaware, the insects that live on Norway maple trees are not the insects eaten by our native bird population. Young birds are fed insects by adult birds, and therefore Norway maples will affect even the bird population.

If the Norway maples are not removed, the native forest will disappear over time, as will many of its native inhabitants and the oak-hickory forest will be replaced by a Norway maple forest with much less biological diversity.