The Friday file: It takes 40 gallons of sap to make 1 gallon of maple syrup, and each tree produces 15 gallons of sap/year. 72% of global maple syrup comes from Quebec, down from 82% in 2003. Trees can only be tapped when nighttime temperatures fall below 32°F but are above that during the day. Due to climate change, that period begins and ends 10 days earlier than in 1970.