It’s the time of year that little green buds start appearing on trees, demanding sugars from the system at large to help them grow. As a result, sap starts to flow through the xylem from the roots to the leaves. Although it may be hard for some to believe that tapping trees can be sustainable, it is fully possible. Trees donate sap like humans donate blood. According the 1989 technical report published by the United States Department of Agriculture, “Sugarbush Management: A Guide to Maintaining Tree Health”, trees can withstand tapping year after year.
Trees typically recover from tap holes and are able to completely grow them over in three years or less. Damage only results from tapping when done incorrectly. Improper tapping can also lead to lower sap production. Care should be taken not to drill too many tapholes into a single tree and to space out the tapholes along the trunk. Additionally, care should be taken not to drill too deep or to drill into a frozen, damaged, or stressed tree. According to the report, tapholes should be drilled about 6 cm deep with an upwards slant. Finally, power drilling will not necessarily cause more damage than hand drilling. It only becomes a problem when people are overzealous for the reasons already mentioned. The report goes on to provide great detail about how to select a tree for tapping, the most efficient methods of tapping, and the myriad disturbances that can lower a tree’s productivity.
Although the previous report states that tapping correctly will not result in tree damage, a study from 2017 in Pennsylvania suggests that annually tapped sugar maple may have a different dendroclimatic response than untapped trees in the spring tapping season. Tapped trees were drilled into and then stuck with a metal spile. Sap was collected via bucket once or twice a day. Once ready, tractors collected the sap and transported it to the evaporator. Tapped trees tended to have below-average growth as measured by ring width indices during years with ideal growing conditions compared to trees that were not tapped. Of course this begs the question, does a lack of growth indicate damage? Or does it simply indicate a lack of growth?
A third study published in 2004 utilized important texts, historical sources, and government documents to better understand the history and sustainability of the maple products industry. It commended the industry as one that unites families, connects people to the land, and cultivates a relationship with the past. Interestingly, at the start of the 1800’s landlords could fence off and then rent sugar trees with strict guidelines pertaining to cutting and tapping. Unfortunately this practice did not stop the destruction of sugar trees as settlers clear-cut land for farming and homesteading. There are records of crude tapping in the late 1800’s and early 1900’s using an axe to create a large notch in the tree trunk. Trees allegedly survived no longer than 8 or 9 years following this form of tapping. There was simultaneous pressure on sugar groves from grazing, which compacted soil, increased runoff, broke roots, and contributed to rot. This all took a toll on sap production. Competition for mature tree trunks to make furniture adds to the pressures on maple as well.
All three studies warned of the consequences of climate change on sugar maple, but also spoke of the joys that maple trees bring. Although more studies should be evaluated, I think it is safe to say that people can “tap in” to this natural resource so long as they do it in a sustainable way. Native Americans were likely the first people to harvest and make maple syrup, and folklore demonstrates the importance of tapping in native communities. Of course, maple isn’t the only tree that offers sweet sap, though it does produce the most, with the highest sugar content, at the highest concentration compared to other trees. According to The Sioux Chef’s Indigenous Kitchen, other tappable trees include boxelder or manitoba maple, butternut, birch, sycamore, and douglas fir. Douglas fir is unique in that its sugar is produced from the tip of the branches and is very difficult to find. Boxelder never produces as much sap as maple. Birch sap goes well in savory dishes. Sycamore is compared to butterscotch. Not only do harvesters use these trees to make maple, but also stirring for different lengths of time creates different results, like with milk churning. Alternative results can be achieved also by harvesting at different times of the year. Other maple products include soft cakes, hard candy, granulated sugar, even wine or vinegar. Indigenous stories about the origin of tapping can also be found on the Michigan State University Extension website and through The Master Gardeners. I encourage you to read more if you are so inclined! Have a wonderful day.