The Toronto Star is reporting that a local plan to tap Norway Maples (Acer platanoides) this spring, collect sap and boil it down into maple syrup has hit a snag (no pun intended) with the proposal to tap the Norway Maples found in city parks: Toronto’s urban forestry department believes that tapping is “detrimental” to the trees.
When I first read the story, I was concerned that there had been a misquote and the plan was to tap Sugar Maples (Acer saccharum) rather than Norway Maples. I checked in with Laura Reinsborough, fellow graduate from the Faculty of Environmental Studies and project coordinator for Not Far From the Tree (the organization behind this idea) if NFFTT’s plans were to tap Sugar vs. Norway Maples. Not so! NFFTT has a post up that explains the whole program in detail.
For the production of syrup, it looks like they only real difference is the lower percentage of sugar in a Norway Maple’s sap. Typically speaking, it takes 40 litres of Sugar Maple sap to make 1 litre of syrup. Based on their research NFFTT is suggesting they will need to collect 60 litres of Norway Maple sap to get that same 1 litre of syrup. Beyond that, the Norway Maple syrup is supposed to be comparable to Sugar Maple syrup.
While NFFTT has to be polite when dealing with the city, I can be a bit more blunt: I call bullshit on the city’s position. Here’s why. Norway Maples are a non-native species of tree that a preferred for urban planting because they often can deal with the stresses of urban settings better than other species of maples. While urban planting practices are changing, they were often planted as a monoculture: street after street of Norway Maple as the street tree. The problem with the Norway Maple is that individuals are now becoming naturalized (meaning that they are growing from the seeds of planted trees rather than just growing in places where they’ve been planted) in greenspaces throughout Toronto. In turn, they are out-competing native species of trees and quickly replacing a mixed Sugar Maple-American Beech forest that would be the undisturbed normal here in the city of Toronto. Additionally, in comparison with that mixed Maple-Beech forest, Norway Maples shade-out most of the herb layer growing under its canopy. This loss, especially when Norway Maples grow in the ravine system of Toronto, leads to increased erosion. In short, while I dislike dichotomized concepts like native/non-native and invasive/non-invasive, these trees pose a serious ecological problem.
The City of Toronto, to their credit, have recognized the invasive nature of the Norway Maple and publish material describing it as an invasive species [pdf alert] including information on how to control it:
Norway Maple seedlings may be dug out of the ground. Cut small saplings at the base using hand pruners or loppers. Small to medium sized trunks can be girdled.
But do we get the irony yet? The same department that publishes the brochure suggesting that Norway Maples are invasive and should be dug out of the ground, pruned or girdled is the same department now saying the Norway Maples found on city property cannot be tapped for sap.
The benefits of tapping Norway Maples outweigh the concerns. If tapping occurs using time-tested procedures ensuring that over-tapping does not occur1 then there is little, if anything at risk for the health of the tree. There is, as NFFTT outlines, another benefit from this plan: the possibility of citizens’ engagement, understanding of and experience of our “urban forest”. Given that the City is already working to remove Norway Maples, why shouldn’t we find some benefit instead?
- Simply, the proper number of taps is based on of the diameter of the tree, never to go beyond four per tree [↩]