Vacuums and small trees

[Grabouss]

We often see articles saying not to tap smaller that 10, 12 inches, depending on the source. The reasoning I often see is to not harm the tree. So them we look at vacuum systems that can double your sap yield. I’m no biologist and no veteran to maple sugaring by any means but this makes me wonder, which guy has the more potential of harming the tree? The guy tapping an 8” tree with a bucket or the guy tapping a 12” tree with a vacuum system?

[metalhead62]

the problem isn't removing sap it is the tap hole itself and what is called ringing a tree which is putting so many holes in a small tree that it cant grow fast enough to allow the tree to heal while the hole its self may heal it also needs to heal inside where you cant see it a couple inches so each side of the hole will compartmentalize and if done long enough it will start to look like a big burl in the middle of the trunk and or kill the tree

[Grabouss]

Thanks for the info. Certainly makes sense!

[DrTimPerkins]

There are two factors that are important in the sustainability of tapping. Wounding (which is what most tapping guidelines are based on) and carbohydrate (sugar) extraction. For the most part, as long as tapping guidelines are adhered to, and trees are growing reasonably well, the amount of wood growth in the subsequent growing season offsets the wood and water transport capacity that is "lost" by wounding (the compartmentalized area or visible stain we see within the tree that is no longer functional for water transport or sugar storage). When trees are not growing well (too dense a stand, poor nutrients, insufficient water, etc), and the stress is prolonged, then wounding, especially if trees are overtapped, could be a problem. In terms of carbohydrate extraction, typically only a small fraction of the sugar reserves are removed by maple production...even under vacuum. Where it becomes an issue is again for small, especially suppressed trees. Those are living near the carbon breakpoint (they don't get enough sun in the understory to grow much), so any amount of sugar extraction can be detrimental, when with gravity or vacuum.