Sap Quantity at Study Sites in the Northeast

Maple syrup is produced from the sap of sugar maple collected in the late winter and early spring. Native American tribes have collected and boiled down sap for centuries, and the tapping of maple trees is a cultural touchstone for many people in the northeast and Midwest. Because the tapping season is dependent on weather conditions, there is concern about the sustainability of maple sugaring as climate changes throughout the region. Our research addresses the impact of climate on the quantity and quality of maple sap used to make maple syrup. Sap was sampled at 6 sites across the native range of sugar maple over 2 years as part of the ACERnet collaboration. At each site we sampled 15-25 mature sugar maple trees, and an additional 10 red maple trees at 3 sites. Sap from mature trees was collected using traditional gravity tapping methods following accepted tapping guidelines for gravity tapping. Xylem sap was collected from mid-February through late April, depending on the site, on all days of sap flow. Sap volume and sugar content were measured for each tree during each collection.