Year 4 of gravity tubing experiments in Underhill, Vermont. This line of 3/16 tubing has 37 taps. 

On April 17th, the vacuum at the uppermost tree was still 25.5” and here, 30 trees down the line, it is 24.5”. Like the Energizer Bunny, it just keeps on running, with no maintenance since the trees were tapped in early March, other than pulling one tap from a hollow tree. 

So far, this line has produced 36 gallons of sap per tap from trees that are mostly no bigger than 12” DBH.

Published: June 2013