Several years ago, a new method of producing maple sap for conversion into syrup was announced. What the researchers did was grow many small maple saplings, then cut their tops off and suck sap out of the end with vacuum equipment. This lasts for something like 7 years before the trees die and need to be re-planted.
Multiple people, including the original researchers, have considered that this would be more sustainable if coppiced trees were used, with one limb/trunk (I don't know the coppicing term) being cut and sucked at a time, while the plant as a whole can continue growing. This could also allow other products to come from the trees if it works right. The problem is that there doesn't seem to be any record of someone trying this yet.
So I came here to ask: has anyone tried this (and just not mentiond it), or would anyone be willing to try it?
The most obvious thing that we would want to learn is whether this allows the tree (or other woody plant) to keep growing at all - if not, then there would be no point. We also need to know things like whether the growth of the tree is affected somehow by sap extraction, whether this makes previously non-viable trees into commercially viable sap trees, whether this can dry out the ground and kill guild plants, and whether sap can be harvested out-of-season.
Here is a list of plants that I think have potential to be tested for this:
maples (Acer spp., likely including strange ones like vine maple, this is the standard on the market)
birches (Betula spp., probably the second-most popular after maple, produces after maple by a different mechanism, tastes spicy and savory, burns if reduced by only boiling)
alder (alnus spp., much like birch)
hophornbeam (Ostrya spp., like birch but produces even later, wood might be quite valuable in poles)
other Betulaceae plants (all of them should be much like birch)
lindens (Tilia spp., produce bast fiber and edible leaves too)
plane/"sycamore" (Platanus spp., the syrup tastes like butterscotch)
walnuts (Juglans spp., probably varies a lot between species)
hickories and pecans (Carya spp., a version made from bark and sugar is more popular, but the relationship to walnuts makes it likely)
all grape vines (Vitis spp., well-regarded as a survival source of sap)
other Vitaceae vines (probably, since others can climb to the canopy like the recognized grape vines)
chestnuts (Castanea spp., rumored)
beeches (Fagus spp., rumored)
apples and crabapples (Malus spp., just a guess, would be good for sour candy)
mulberries (Morus spp., just a guess, seems to produce bast fiber)
osage orange (would produce orange dye with potential medicinal value, but risky to both equipment and health)
tulip tree (Liriodendron, reports seem to refer to flower nectar rather than syrup, but extracting sap might work anyway)
poplar/cottonwood/aspen (Populus spp., rumored)
elm (Ulmus spp., rumored)
edit: removed the latex and resin entries because I'm about 80% sure that they don't work like that anyway.
I have not done it. I am aware of the research you're referencing. I'm planning on coppicing a number of maples on our site this winter. I had not considered doing this. Now I will have to think about it ;) Another possible approach would be to pollard an appropriate sized tree, do the vacuum tube extraction immediately after cutting, then let it proceed as a pollard, not revisit it for extraction, but instead pollard another for the next season. Not quite the same, but might work with trees that won't take pollarding.
As I recall, the study didn't appear to indicate any harm to the young trees from the extraction, just the injury of cutting them off. That suggests to me that pollarding should work just fine. It also implies that you're not likely to harm the coppiced tree, but empirical evidence is called for.
dangit, another item on the to do list.
Forgot to mention that certain trees, like hornbeams, tend to grow multiple trunks without interference, and I think that works just like coppicing. If so, some people could test this idea without even coppicing a tree themselves.
Joshua Seewald wrote:and whether sap can be harvested out-of-season.
It isn't possible to get syrup-quality sap at that time of year regardless of the production method. The trees are producing "buddy syrup", in relation to the budding that occurs in early spring when warmer temperatures occur, which causes the sap to taste bitter. Sugar content is much lower as well, and I'm not sure what other value it might have outside of the tree's usage. Depending on location, a 1 month period between January-April is the normal time of year to collect sap for syrup. There have been some experiments done by tapping from September-November, which also produce viable syrup-sap, but I haven't read up on the research much.
I have no problem testing this newer method come March, and could easily find some of younger saplings that are "weeds" in an orchard I have access to - just depends on my time and budget.
From what I have read, the criteria/process is something like this:
Capping - a thick plastic bag over the top, with a hose clamp around it and the tree, and a spout into the bag. Apparently there is enough pressure that the sap just goes into the spout. I'm sure better items exist to create a better seal with more direct contact for sap to flow into the tube
Spout size - Not sure if there is an ideal spout size
Trees - I've read the trees need to be chest-high, 3-4'' in diameter, no bigger or regrowth is lessened. I'll personally test based on that criteria as it's all I've been able to find.
Tubing/Vacuum Pump - I'm unfamiliar with vacuum systems, so I'm not sure what size of tubing is best for them. 5/16 is what the instructable used
Anything else that needs to be considered?
"Our ability to change the face of the earth increases at a faster rate than our ability to foresee the consequences of that change"
- L.Charles Birch
Joshua, I have heard of this research too, back when it came out. I thought it was a nifty idea, both for the short establishment period and the higher yields. Re-reading it just now, there's even more interesting ideas such as selecting sweeter trees (likely not considered in the past) or regenerating damaged sugarbush (not just by replanting, but possibly by coppicing!).
I have thought it would be fun to try, but there always seem to be too many "fun projects" in the queue.
Since you are new to Permies, welcome!
I understand what you are getting at by saying "coppice" and it's interesting to add that extra layer of pole/wood harvest to the maple sugaring (or maybe it's the other way around). I don't know if the best time for cutting for the poles/wood is the same time as for sugaring? (It could only really matter if it's the worst... but not sure if sugars in the bark/wood would make it undesirable due to rot/decay/insects?)
The methods in the study could be thought of as simply "pruning" OR they could also be "coppicing" or "pollarding" (which could be interesting since the sap tubes are often setup for gravity flow to the tank, and different heights of pollard could establish a slope)
A "plantation" is merely a managed woodland, and coppice could be the method of management. In the article they refer to the proposed system as "plantation" to compare to current system of old, often wild, sugarbush.