Not that it really matters, but the article also refers to it as “drawing water to the top”. That seems more representative of reality than “pumping water from the bottom”.
This is why the question is interesting. You can't just suck water to the top of a 60 meter tree. There must be some kind of positive-pressure pumping involved.
There's no free lunch here. The Sun drives the evaporation, and if the tree were in a closed system with no solar input, the humidity would eventually get high enough to stop it.
... that would be the least of the tree's problems.
The tree is a perpetual motion machine hooked up directly to the wheelworks of nature! It PUMPS 500 liters per day usibg Wind, solar, capilar action and evaporation! How do i charge my car with this?
The other day my friend said they wanted a new nervous system and my brain went down this route of pulling out the old one and putting in the new one.
Is the new nervous system really you?
Simard attributes intention to this, but osmosis is “fair”. It seeks to move water to where sugars are and sugars to where water is. So a plant giving up sugars will receive water, and one low on water will give up sugars in the process of equalization.
Do fungi contain pumps to maintain disequilibrium in this work? I could not say. But even when they first learned the trick of tapping roots the basic premise would have worked in a rudimentary fashion woth no further optimization.
As a largely unrelated aside, there will still be a chemical potential across a membrane that doesn't permit a solute to cross. So water can diffuse into a concentrated solution without the solute flowing backwards into the reservoir. Alternatively, small solutes can leave while larger solutes are retained. This is the basis of dialysis.
Trees aren't even accessing water at ground level most times but pulling it up from 5-30 feet down. Fungal distribution is also a capillary action network (with asterisks) and ends up making some of that pumping more horizontal, but at the expense that if a tree's root sap is high in sugar due to dehydration, then the fungal network both introduces water to those roots but also exports sugar at the same time. Simard tries to anthropomorphize this process. It's my only real complaint with her work.
The asterisks are that fungal networks can react to information faster than the documented transport mechanisms work so we don't really know how the heck they do their thing yet. So it's possible that they're also maintaining nutrient gradients to feed themselves beyond the straight arbitrage that osmosis represents.
In a tree the inlet to the “pump” is at the base of the tree. It’s not like there’s a pump sitting in the tree at 80 metres trying to suck water up from the ground, that would obviously fail. It’s more like a very long pump.
More generally you seem to be dismissing out of hand the primary topic of discussion which is neither constructive nor enlightening.
Or the high pressure is down here, whichever way you want to look at it.