Sap!

I got home at dusk tonight and decided to check my maple trees. Earlier in the week I set an empty milk jug beneath each tree and attached vinyl tubing to each tap. The other end of the tubing went into the milk jug.   The weather wasn't super warm today so I wasn't expecting to get any sap but I wanted to be sure the strong winds hadn't knocked off the tubing.  I checked the 3 taps on the box elder trees first.  All the tubes were attached and dry.  One milk jug had tipped over but the tubes were still inside it.  Next I checked the east maple in the front yard.  Holey smoley - there were droplets in the tubing and about ten ounces of sap in the milk jug.  My plan is actually working!  This is the tree that I accidentally broke a tap. Below that broken tap was a large area of wet bark.  I saw a twelve inch wet stain on the bark.  The west maple had tubes in place but they were dry.  I imagine the east maple gets the most unobstructed afternoon sunshine and that is why it is the first one to deliver sap.  According to those who know, the fluctuation in the air temperature is what makes the sap flow.  When it is warm, positive pressure inside the tree forces the sap to flow out of wounds or tap holes. When the tree gets cold, negative pressure draws up water from beneath the roots replenishing the sap.  The sugar is from the photosynthesis of the previous summer.  Amino acids in the sap give the sap the distinctive maple flavor - very different from plain sugar.  Tapping the tree takes away less than 10% of the tree's sugar - not enough to harm a healthy tree.  That reminds me, two years ago I tried to cut down one of the box elder trees I tapped.  I used a reciprocating saw and a bow saw.  I was unsuccessful but I cut the bark nearly all the way around the trunk.  I wonder if that tree will give any sap at all.  All my sawing did not negatively affect it's green leaves though.  I'll just have to wait and see.