Final report for climate effects on the culture and ecology of sugar maple

Abstract

Maple syrup is produced from the sap of sugar maple trees 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. At the same time the demand for this natural sweetener and the production of maple syrup are increasing rapidly. Our research addressed the impact of climate on the quality of maple sap used to make maple syrup. We examined yields coupled with the sugar and biochemical composition of sap collected throughout the geographic range of sugar maple in the northeastern USA and Canada, and related this to historical and projected variation in climate. This is the first study to document potential climate related changes in sap production and sap quality across the full geographic range of sugar maple. Declines, as well as increased variability, in sap flow near the southern range limit and increased sap flow at the northern range limit suggest long term range shifts toward the north, as well as geographic variation in expected syrup production over the next several decades. Survey results highlighted that producers do perceive changes in climate variables and concomitant shifts in sap production. Many producers are willing to shift sap harvesting practices in response to changing climate scenarios, but producers are split in their perceptions about the importance of individual variables and their level of concern about future impacts on the industry. Overall, our results can be applied to design more effective extension programming and adaptation plans to mitigate the risk of climate in maple systems.