The weather is starting to warm up as we enter early spring, which means maple syrup season is here! Maple sugaring is the centuries-old American tradition of tapping maple trees for their sap. Maple sugaring is a hallmark industry of our eastern forests, but this industry is now at risk due to the effects of climate change.


There are over 100 species of maple trees, but only three produce enough sugar to efficiently make syrup. These three North American species are the red maple (Acer rubrum), the black maple (Acer nigrum), and the sugar maple (Acer saccharum). The sugar maple is the most commonly used for syrup production. New York is the largest syrup producer in the Chesapeake Bay watershed, with Pennsylvania coming in second, but maple syrup can be produced anywhere in the watershed.

True maple syrup is completely made out of sap (a mixture of water, sugar, minerals, and antioxidants) which is collected by “tapping” a tree. The excess water from the sap is evaporated through boiling, leaving a thick sugary substance behind that is then bottled and sold as syrup. Tree tapping consists of drilling a hole about 1.5 inches past the bark of the tree, hammering a metal tap into the resulting hole, and placing a bucket under to collect the flowing sap. Since sap is mostly water, 40 gallons of sap will produce only one gallon of syrup. The average sugar maple tree produces between ten to twenty gallons of sap each sugaring season.

The sugar making process in maple trees starts when weather goes above freezing and shuts down once it starts getting consistently warm. Maple trees typically use the sugar from the sap to fuel wood production and bud growth, and to maintain overall tree health. Maple trees mass produce sap in early spring, when weather at night is about 20 degrees fahrenheit and stays between 30 and 40 degrees during the day. Collecting sap too early causes an off-tasting product, and collecting too late results in small sap loads. Since sugaring maple trees require such specific temperatures, this process occurs exclusively in North America.

Although inserting a tap into a tree causes a wound, the tree is not hurt during the tapping process if the hole is drilled properly. In fact, the tree protects itself by producing extra cells to wall off the hole. Sap collection also doesn’t hurt the trees. Since the sugaring season isn’t until the end of winter and occurs in colder states, there’s plenty of water available from melted snow for the trees to absorb in order to stay healthy.

Image from Shutterstock


The use of maple tree sap goes back to the late 1500s when Native Americans discovered they could substitute it for water while cooking. Research has indicated that they used the sweet sap to boil their meat. Records from early settlers note that the Native Americans “get juice from the trees and distill it down into a very sweet and agreeable liquid.”¹ Dairy farmers who came to the United States during the 17th century often used sugaring as a way to supplement their income. Up until the early 19th century New England colonies used maple sugar cakes as a form of currency until honey and sugar cane were introduced.

The process of extracting sap from trees has remained much the same since the 1600s. The same general concept is practiced, but now instead of having a bucket at every tree, maple syrup producers connect tubing to the taps and all of the sap is collected in one place. Evaporation devices allow for some of the water from the sap to evaporate before it is even collected, and suction devices collect more sap than traditional taps. These inventions help offset the cost of syrup production.

Syrup production has increased in the United States since the introduction of this new sap collection technology. In 2012, 1.9 million gallons of maple syrup were produced in the United States.² In 2017, production more than doubled, producing 4.271 million gallons, bringing in $147 million dollars in income.³ For a season that only lasts about a month, this is an important industry for rural communities, providing income during what would otherwise be the off season for most other agricultural production.

Image from NPS Stock


Climate change is the greatest threat to maple syrup production. Up until the mid 1900s, the United States was responsible for producing 80 percent of the world’s syrup, while only 20 percent came from Canada.¹ Today it is the complete opposite. Because of the effects of climate change, the temperature range required for maple sugaring are now found only at higher altitudes. Historically, syrup producers waited to tap trees until about the first week of March. Today, the average season begins in mid-February. With the fluctuating start dates to the sugaring season, syrup farmers have to be cautious of when they start tapping. Tapping earlier in the season can result in an unusable product, while taping too late in the season takes the risk of missing a heavy sap flow day. A longer sugar season, with less usable syrup also means farmers have to pay laborers to work more hours. The trees are also producing less sugar in their sap. The sugar content in sap was 4 percent in the 1950’s, and now it is down to 2 percent.¹ This is because the photosynthetic process that is responsible for making sugar in the maples shuts down when the weather gets too hot.


For centuries, maple syrup has been a staple of the forest product industry in North America. For some, maple sugaring is a hobby, but for many, it is an important business and major contributor to the economy. The effects of climate change are threatening syrup production and altering their sugar content. Fortunately, modern advances in sap harvesting technology helps keep this important industry alive.

Many states celebrate the natural sweetness of maple syrup with local festivals. Maryland’s Cunningham Falls State Park Maple Syrup Festival, Pennsylvania’s Maple Harvest Festival, along with the state’s 71st Annual Maple Syrup Festival, New York’s Maple Weekend, Virginia’s Highland Maple Festival, and West Virginia’s Maple Syrup Festival, are just a few that are fun for all ages to attend this March.

Have a maple tree in your backyard, and want to identify it, or try to tap it yourself? Click here to learn how to identify different species of maple trees for syrup production and for a step-by-step guide on tapping!

  1. Brown, Sarah “Global Warming Pushes Maple Trees Syrup, to the Brink” National Geographic (2015)
  2. Statista, “U.S. Maple Syrup Production by State” (2017)
  3. Agricultural Marketing Resource Center, “Maple Syrup Profile” (2017)