Drought and maple syrup

With the recent snow and cold weather, last summer’s dry heat seems like a distant memory. Yet, it was only this past week that the National Weather Service officially changed its “moderate drought” designation to “abnormally dry” for most of Lake County, Illinois (although, a small northwest portion of the county is still considered to be in a “moderate drought”). While every drop of rain and flake of snow is helping to slowly ease our way out of the past eight months of drought, the damage already done will decide the sweetness of this spring.

Each spring for the past three decades, the naturalists at Ryerson Conservation Area have tapped sugar maple trees to harvest the sap and turn it into pure maple syrup.

While we will continue the tradition again this year, we will be handling the process a bit differently due to the drought. Reduced precipitation levels last summer caused local trees to produce smaller leaves, which dropped earlier than usual this past fall. Leaves are the food-making factories of a tree, combining water, carbon dioxide and sunlight to produce sap. Trees use this sap for growth and damage repair. It is this same sap that we collect small amounts of from the sugar maple trees each spring for syrup production. The reduced size of these leaf “factories,” plus a shorter sap production time, leads to less sugar content in the sap, which typically means less maple syrup produced overall.

A case study by the New England Regional Assessment of two Vermont maple stands in 1998 and 1999 looked at the impact drought has on the sugar reserves stored within the roots. While precipitation in 1998 was normal in that area, 1999 was a significant drought year. The study found that during the drought of 1999 there was 70% less root starch and 50% less stem starch than in 1998 (starches are later converted into sugars). This led to the conclusion that precipitation levels and the previous summer’s growing conditions are likely to impact sap flow and syrup production during the following winter and spring.

Prolonged drought can have long-term impacts on the health of trees, making them more susceptible to disease and insects. Less sugar stored, smaller leaves, earlier leaf drop, and branch die-off are all responses that trees may have when stressed by an inadequate water supply. In typical years we tap 30–35 sugar maple trees at Ryerson, causing little to no damage to the trees. In an effort to curb potential stress to these sugar maple trees—based on recommendations from the University of Vermont’s Proctor Maple Research Center—an even more conservative number was tapped this year: 10 trees. Our popular Maple Syrup Hikes will continue unchanged, and each participant will still get a taste of our own maple syrup. Let’s hope rainfall this spring will reverse the “abnormally dry” conditions we’re experiencing now and will continue through a healthy summer, carrying us into a sweeter maple syrup season next year!

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