A little something for the "for what it's worth" department.
There's a Northeast Ohio member here with the following in his signature;
"Tapping the same trees my great, great and great grandfathers tapped".
So... If we allow 25 years per generation, that gives us 100 years; guessing this member is 30 something gives us 130 years of tapping these same trees. Estimating that these trees were close to 50 years old before they were tapped and we have a bush with 180+/- year old trees - still healthy and still producing. Assuming these older fellows were using 7/16" taps - and maybe even putting 3-4 per tree, we now have 180+/- year old healthy trees that have been tapped for 130 years using older technology.
With all of that said; in the past four weeks, this bush and this member, have produced 53 gallons of syrup to date, on 225 buckets and 50 gravity lines. He produced 127 gallons in 2010 and I can only guess he uses 5/16' spouts now. The numbers and the history are impressive and speak loudly for the sustainability of producing maple syrup and the tenacity of the sugar maple. These men have obviously taken care of their woods.
I am not supporting vacuum or gravity one way or the other - I just don't know enough yet - and I have a lot of respect for what the good Doctor has to say about his chosen field. As for the long term effects of tapping, whether we should be on gravity or on vacuum, and how many taps are acceptable I for one, respect his opinion.
John Allin
14x18 Hemlock Timber Frame Sugar House 2009
Leader 2x6 w/Patriot Raised Flue Pan 2009
Leader Steam Hood 2014 - Clear Filter Press 2015
Leader Revolution Pan and SS Pre-Heater 2016
CDL Hobby RO & Air Tech L25 Hi Vac Pump 2019
06' Gator HPX to collect wood & sap
14' Ski-Doo Tundra for winter work in the woods
Great Family 3 grown kids+spouses and 7 grand kids who like the woods
7th Gen Born in Canada - Raised in Chardon Ohio - Maple Capital of the World..<grin>.