- The north eastern part on North America was once tree covered with a forest type known as the Carolinian Forest. This was a mix of various hardwoods and softwoods. Dominating the forest was a the mighty sugar maple. In the early spring as the frost is coming out of the ground the sap begins to "run." This means the sap starts flowing to the upper reaches of the tree. The maple sap runs about 1 inch below the surface of the tree bark and provides the nutrients for the foliage and new growth of th