What causes sap to flow?
The freezing action during the winter months and spring nights allows maple trees to produce large quantities of carbon dioxide gas. It is this gas which forces the sap to flow upward inside the tree during the warming cycle of the day. The sap moves along a pressure gradient from a zone of relatively high pressure to a zone of lower pressure. About 36 to 48 hours of below freezing temperatures, followed by a warming trend of + 5 °C are needed for good sap flow. If the trees are frozen, it normally takes longer for sap flow to occur, regardless of air temperature. It is thought that gravity may also have a role in sap flow. • Through what tissue within the tree does the sap flow? The sap flows through the outer white coloured wood which is called the sapwood. • Will the removal of sap be harmful to the tree? In a manner analogous to a blood sample taken from a healthy person, the removal of sap from a tree will not harm it, provided that proper tapping guidelines are followed. This inc
