Monday, May 29, 2006
CBC News is reporting that invasive Norway maples (Acer platanoides) may be replacing the famous sugar maple forests of Mount Royal, Montreal. A biologist surveying the forest categorized the maples by age class, and noted that while older trees are predominantly sugar maple, trees less than a decade old are three times more likely to be Norway maples. The planting of Norways as street trees and to replenish the forest is thought to be at least partly to blame. One of the unfortunate outcomes of the spread of Norway maples into the Mount Royal forests is that the autumns of Montreal are now lacking in the glorious reds of the sugar maples - Norway maple leaves turn yellow.
This problem isn't just in Montreal. Most urban areas in central Canada prefer to plant the more salt/pollution tolerant Norway Maple over the native sugar maple. Unfortunately, Norway maple often escapes from these horticultural settings and moves quickly into adjacent native forests; often spreading without notice. Identifying a Norway Maple from a Sugar maple during the summer months can be difficult - the easiest way is to squeeze the juice out of a leaf's petiole and check if it is clear (sugar maple) or white (norway maple). The species are difficult to distinguish from one another based solely on the bark and leaves of the tree, and nearly impossible where seedlings are concerned. Norway Maples are a problem in Ottawa, London and Montreal and likely in communities between them.
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