Recently, on February 2nd, there was an article on the local TV news regarding the tapping of large leaf maples for the production of maple syrup.
I have been asked if tapping maples is harmful to the tree. Much research has been done regarding this question.
Removal of the sap, (the trees food) which is not maple syrup until it is refined through boiling, does not hurt the tree too much. Experiments in which eight to twelve times the normal amount of sap was removed yearly for five years did not detectably slow the annual growth. The damage done is directly related to the number of taps used.
Each tap hole is a wound that the tree must “heal”. Unlike humans, trees “heal” their wounds by sealing off (compartmentalization), rather than repairing the damaged tissues as we humans do. Every tap hole represents an area of damaged tissue that will never be functional again, either for nutrient water transport or food storage. Also, until the hole is compartmentalized it acts as a route for diseases and or insects to enter the tree. The average sugar maple tree lives approximately 50 years.
Other recent studies have suggested that a smaller drill hole and tapping tool, half the regular size, still allows for good sap flow and much less damage.
One final note; it is against the City of Nanaimo’s Parks, Recreation and Culture Regulations Bylaw and Tree Management and Protection Bylaw to do this activity on public property. I thought it was important to clarify this after finding a few maples tapped in one of our City parks.
So if you are interested in this food production hobby, please ensure you do so on private property.
* Thanks to the University of Minnesota for some information in this article.
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Alan Kemp is the Urban Forestry Coordinator and has been in that position since September of 2006. Prior to that he was the Horticulture Foreman for the City Parks Department. Alan has worked full time for the City since 1986, but originally started with the City in 1976. Alan graduated from UBC in 1980 and also has a diploma in Horticulture from the University of Guelph.