The maple syrup that's tapped from the tree may not be as fresh as you think it is.

Sugar maple trees can store carbon from the atmosphere for several years in non-structural reserves as a buffer against disturbances such as droughts, hurricane damage, or attacks by insects. A new study shows that trees draw on this reserve when springtime sap begins to flow.

Thus, the sweet sap of maple trees integrates sugars produced during several growing seasons. The findings may provide new insights on how trees store and regulate the availability of nutrients.

"Our findings might be interesting news for maple syrup producers, as they suggest that springtime sugar mobilization in maple trees depends on reserves built up over several years rather than on just the last season," said Dr. Jan Muhr, lead author of the New Phytologist article.