Like many plants that European settlers brought with them to North
America, intentionally or by accident, Norway maple has become
something of an unruly and unwelcome guest. Thousands of Norway maples
have been planted as street trees throughout eastern North American, and
these trees have released millions upon millions of seeds into the
environment. The seeds that land on a nearby lawn may germinate, but
they are soon mowed before they become very tall. However, seeds that land in
vacant lots or get washed down the storm sewers to the banks of the
streams and rivers that flow through our towns have the chance to
germinate, grow, and flourish. Now, these Norway maples are more than
just occasional upstarts - in many areas they outnumber and are
out-competing the native trees of our riverside (riparian) forests.
This story is echoed hundreds of times by other Eurasian plants that
were brought for our gardens or came as weeds in our crop seeds. Garlic
mustard, purple loosestrife, European buckthorn, giant reed grass
(Phragmites australis), Scots pine, black locust, tree of heaven, ... the list is huge, and growing. Not only
do these non-native plants out-compete our native plants (and thus make
some of our native plants more and more rare), they frequently
perform poorly as food, shelter, or habitat for the native fungi and
animals that formerly depended on native plants for these functions.
Invasive species are second only to habitat destruction as a cause of
the loss of biodiversity worldwide. Growing only native plants in our
yards and gardens is something we can all do to help reverse
these trends. To read about a Biodiversity Garden in-the-making in London, Ontario, click here.