Ask me again in about 3 years.
To preface this post, note that our previous research has shown that the spring season has been moving earlier in the calendar year for at least the past 50 yrs. Models we have done indicate that the fall season (which most people ignore) is corresponding moving later and later in the calendar year. At some point, it is possible that these two very distinct seasons will merge into one (at least initially) longer season. At this point however, the two seasons are still separated by a fairly long period which traditionally could not be spanned -- a taphole would not be viable (produce sap) for that length of time (November through April) without experiencing a good amount of "taphole drying" and loss of yield. However, given all we've learned over the past 10-15 yrs about taphole sanitation, we've broadened the length of time a taphole is viable enough to make it worth investigating.
Note that this is a study I've been wanting to do for about the past 10 years. Other things kept getting in the way (funding being one). However, we were very fortunate to have just received funding to do it, thus this happens to be the last "major" study I initiate before I retire.
To start, we selected three groups of well matched trees. All will be on vacuum. Some we tapped in November. Of these, some will be let as, some will be drilled 1" deeper, and the rest will be reamed larger (they started at 1/4" rather than 5/16") and also drilled 1" deeper, as we get closer to the "normal" sugaring season. A forth group of those trees will have tubing to the first taphole cut and capped and a 2nd hole drilled 2" above the original taphole (to reduce adding more stained wood from a 2nd taphole). For all treatments that are changed, a new spout will be added when we redrill/ream.
Another set of trees will be tapped in mid-January. A subset of those will be drilled deeper in the spring. Another subset will be reamed and drilled deeper.
A final set of trees will be tapped at the more traditional time.
Altogether that makes 8 treatments, with 10 trees per treatment. Periodically we will measure sap yields and sugar contents. Study will be repeated for 3 years to account for seasonal variability. If you've seen the recent (December 2017) Vermont Maple Mainline
https://www.uvm.edu/sites/default/fi...ember-2017.pdf the photo on the front cover shows just one section of the chambers we are using for that study. In total we have over 80 of those large chambers....research ain't always cheap.
Much of our research on climate change over the past several years leading up to this project has been funded donations from Tonewood
https://www.tonewoodmaple.com/ The project I describe above is primarily funded by the USDA ACER ACCESS program and is also sponsored by Lapierre Equipment Co. (by a generous reduction in price for the chambers).
As far as "how much is too much"....that's a different question altogether (but related). We've started on that one a while back. We finished Yr 4 of a total of at least 5 Yrs...more likely it'll end up being 10 Yrs or more before the project is completely done (by which time I will be long gone), but we hope to release the 5 Yr results at the end of 2018 or beginning of 2019. So once again, I'll have to answer with "ask again" next year. We have a major publication planned that will summarize all our work (about 8 individual, but related projects) on what we call our "Sustainability" project. Should come out in about 2 Yrs.
So hopefully that illustrates that we tend to plan ahead a fair bit. You'll just have to stay tuned.