The maple syrup season at Cornell's Arnot Forest has been good so far. We started production earlier than usual, and currently have about 60% of an average crop. We average 500 gallons per year; currently we have 285 gallons with more as I type. The weather is optimistically good through the beginning of next week. We are looking forward to another great Maple Weekend on March 17 and 18.
The picture below shows the inside of a check valve on one of my research trees. The check valve, normally used with a tubing system, prevents the tree from pulling sap into the tree during a freeze as the tree's internal pressure goes negative. The resorption of sap moves bacteria and yeast into the tree. These microbes accumulate and grow in the tap hole, eventually plugging the xylem vessels and ending the season. The check valves aren't essential on my research trees, but the picture is a nice illustration of the flow of sap.
Speaking of the flow of sap, check out this video of the vacuum releaser. The releaser allows for the sap to separate from the vacuum without losing vacuum inside the tubing system.