Does the loss of sap or damage from tapping impact long term health of trees more?

[Vermont Creation Hardwood]

With the advent of vacuum, the amount of sap removed from our maples has roughly doubled. The check valves may increase that even more. At the same time the size of damage from tapping has decreased with the use of smaller taps. The question I've not seen answered: does the large increase in the amount of sap removed per tap affect the long term health of maples negatively?

For the gravity system producer, can he double the number of taps per tree in order to approach the yield of vacuum systems? The damage per tap is reduced with modern smaller taps.

One worry I have is that the bias of the maple industry is for researchers to find that the greater sap yields don't harm the trees. I have not seen studies that address this issue, potentially one of the most important issues for the maple industry. Is there any truly independent research ongoing to address this?

[SWEETER CREATIONS]

I think maple producers have been using vacuum in Canada for over 25 years with little to no ill effects on their sugar bushes. We just started using check valves and vacuum last year, cant really comment on the long term effects yet ,but I was in the sugarbush in October and the trees had already healed up with the check valves where as the old 7/16 taps were far from healed up. Just my first year again with vacuum and check valves they seem to be what is needed, so we ordered 1000 for next year again. I too questioned the harmful effects and for me these are way less damaging to the trees and will again be using them in the future. Ive seen no harmful defoilation in the sugarbush as of yet.

[maplecrest]

after using vacuum for over thirty years, and seen the damage done to the trees i tap from 6 generations of tapping i will say that smaller spouts heal in a few months. trees give more sap than they need. mother nature plays a bigger roll in this. wind damage, lightning.drought ect. the big thing that had me thinking this tapping season was the lack of snow. and dust flowing up under my feet as i walked along tapping. but since then we have had rain and it is snowing now.but in dry years past the sap does not run long no matter how high the vacuum. the tree will give you what they can. over tapping will do more damage to a tree than any thing in my mind

[happy thoughts]

For the gravity system producer, can he double the number of taps per tree in order to approach the yield of vacuum systems? The damage per tap is reduced with modern smaller taps.

One worry I have is that the bias of the maple industry is for researchers to find that the greater sap yields don't harm the trees. I have not seen studies that address this issue, potentially one of the most important issues for the maple industry. Is there any truly independent research ongoing to address this?

Interesting questions. I would tend to think that the introduction of more foreign bodies like taps would be more damaging to the tree than sucking out more sap. So no, I don't think gravity tappers can add more taps past the current recommendations.

I've read that tapping removes less than 10% of a trees sugar stores and that's supposedly not enough to cause long term harm in a healthy tree under normal growing conditions. Also I would think that with spring a few weeks off, the tree will soon leaf out and will make more sugar in short time. It sounds like vacuum systems have been around long enough that adverse effects from it would have been long recognized. And since sugaring is big business, I would tend to think that even "dependent" researchers would keep tree health a priority. You kill the tree you kill the industry.

The use of smaller taps would also make me think they are less damaging so whatever damage loss of sap from tapping causes, if any, I'd think is easily overcome from less damage to the living parts of the tree which will be better able to produce more sugar... and so on and so on. But these are just my own uninformed thoughts

[DrTimPerkins]

The question I've not seen answered: does the large increase in the amount of sap removed per tap affect the long term health of maples negatively?

Vacuum yields in the range of 0.3-0.4 gal/tap have been achievable for at least the past 30 years with no apparent ill effects. High vacuum/good sanitation yields of 0.5-0.7+ gal/tap have been made in the past 10 years. Despite this, there don't seem to be any obvious ill effects from such sustained yields.

For the gravity system producer, can he double the number of taps per tree in order to approach the yield of vacuum systems? The damage per tap is reduced with modern smaller taps.

Not advisable. Doubling the number of taps, as well as the use of deeper, and sometimes larger (since some gravity producers still use 7/16" spouts) tapholes already creates a larger wound in the tree. Increasing the number of taps will increase the amount of non-functional wood in the tree, and is not recommended.

One worry I have is that the bias of the maple industry is for researchers to find that the greater sap yields don't harm the trees. I have not seen studies that address this issue, potentially one of the most important issues for the maple industry. Is there any truly independent research ongoing to address this?

Yes. At the UVM PMRC (I assume you would consider use independent....we definitely don't want to encourage maple producers to use practices that are not sustainable) we currently have three different (but related) ongoing studies examining the impact of carbohydrate removal on tree health and growth. There are other ancillary studies related to this work also being conducted. The overall goal is to examine current tapping guidelines in terms of BOTH tree wounding AND carbohydrate removal rates in order to develop new tapping guidelines based upon each of these two factors (current guidelines were developed with only wounding in mind). Unfortunately, as in many cases, it takes some time to do this work, and then to verify the results, before we can release the findings. So, while I can't yet speak of the results of these studies, perhaps an analogy will help.

You give blood. Your neighbor doesn't. Other than feeling good and helping others, there are really no advantages or disadvantages to giving blood compared to your neighbor. Even your Dr. would not be able to tell if you give blood or not (unless you tell them or they see the needle scars). Giving a pint has no real effect on you either way. Realistically, for most adults, giving a pint, or maybe even two pints at a time once each year wouldn't have any additional effect (unless you were really stressed by something else). Now say your 15 year old wants to give blood too. Probably wouldn't hurt them either - but maybe you'd have a little more concern. But how about your 10 yrs old....your 5 yr old? How about your 5 or 10 yr old that was sick or stressed by something else (like lack of proper diet, or for a tree, lack of sunlight because it's growing really slowly under the canopy of older, larger trees)? Probably not a good idea for youngsters in that condition to give blood (or in the case of a tree, to be tapped) until they're a little older, bigger, and have less stress.

Hopefully we can stop talking about people and blood about a year from now and actually discuss trees and sap.

[PerryW]

but If I have 100 kids, I figure it's okay to send a dozen or two of the younger kids to give a couple quarts of blood? The upside is, after a 5 year old gives a quart of blood, they ain't quite so rambunctious for a few days.

[Vermont Creation Hardwood]

I think Perry's analogy is more apt. After years of giving a pint every year, now we're taking two pints, with the latest technology getting closer to three pints. At what point is it too much? That these studies are ongoing now after 25 or more years of vacuum seems a little after the fact. The answer at the moment then is that we don't know? We don't know how much sap is too much for the trees?

Of course it's not how much is too much for normal years. In these parts a number of years ago we had a very nasty ice storm that stripped maples of most of their branches. I saw trunks that basically only had major branches and those were shortened dramatically. This was over a wide area. They came back, mostly. But if their reserves had been depleted by increasing sap extraction each year, at what point would they not?

On the other hand we thin the stands to give them optimum growth. Does our care balance the sap we take?

As far as the gravity question goes, 7/16 was the standard for many years. Why do you say that dropping to 5/16 does not allow more taps for the gravity producer? I understand that that tree wounding is the concern. Does that mean that the 7/16 taps were too much for all those years?

[northwoods_forestry]

For the gravity system producer, can he double the number of taps per tree in order to approach the yield of vacuum systems? The damage per tap is reduced with modern smaller taps.

Very interesting discussion. I considered going vacuum a couple years back when I was looking to increase production. I decided against it, but rather than doubling the # of taps/tree I have doubled the # of trees I tap. At the scale I'm working this seemed to make more economic sense and I had the trees to do it. Relying on gravity and the whims of nature, however, I don't get the more consistant volume that a vacuum system seems to produce.

[PerryW]

Very interesting discussion. I considered going vacuum a couple years back when I was looking to increase production. I decided against it, but rather than doubling the # of taps/tree I have doubled the # of trees I tap. At the scale I'm working this seemed to make more economic sense and I had the trees to do it. Relying on gravity and the whims of nature, however, I don't get the more consistant volume that a vacuum system seems to produce.

Well said! that's exactly my theory. I just grew my # of taps to fit the amount of wood I'm willing to put up annually for my 1-man show.


Also my trees are fairly spread out and trying to strive for 5 taps on a lateral (for vacuum) would make for an expensive tubing setup. And keeping it simple has it's advantages. No midnight bearing repairs.

[spud]

but If I have 100 kids, I figure it's okay to send a dozen or two of the younger kids to give a couple quarts of blood? The upside is, after a 5 year old gives a quart of blood, they ain't quite so rambunctious for a few days.

WOW.

I read this whole Thread and found it to be interesting at first. Vermont Creation Hardwood had some good questions and was looking for answers. I felt the Doc's explanation was real good and it made a whole lot of sense to me. The comments made after the Doc's explanation I think are foolish.

Spud