> These vessels have evolved intricate adaptations that can maintain the water in liquid form, even under the extreme low pressures
This sentence undersells the phenomenon quite a bit: the “extreme low pressure” is in fact several bars of negative pressure and the challenge of maintaining water in liquid form is avoiding cavitation.
I grow marijuana and chillies from time to time. I got good at it. I will say that plants are malleable in untold ways and so I find this article to be unsurprising.
Plants will do what they need to do in the end. I've done stuff like co2 bombing, and increasing nutrients to the point to where I get a whole new ecosystem of insects and an entirely new situation.
It is such fascinating stuff that it's actually the life I want to live. I'm a computer scientist but now I yearn for the botanical sciences.
I highly recommend checking out defoliation strategies and low-stress training methods for anyone interested. Plants are not dumb creatures. The results you can get from them are astonishing and the science of what plants actually are becomes more profound by the day.
I'm studying for a bachelor's degree in horticulture part-time through a distance-learning university. If you're more interested in growing plants, I'd say horticulture is a better fit than botany. If you're more interested in understanding how plants work, botany is probably the better choice. That said, you'll still learn a lot of botany in a horticulture degree as well obviously
Thank you sir. I actually got my CS from distance learning and somehow the combination of growing things and monitoring everything using CS just grabs me. I would work on any farm anywhere with appropriate agency.
Oooo, I get a bit excited about interdisciplinary techno-plant-and-livestock
Another area that might be easier to break in to as far as work goes is labouring for an irrigation business, kinda agricultural plumbing.
You’ve probably seen pivots[1] and side-roll irrigation systems.
This would put you in more direct contact with the farm operators, expose you to a wide range of agricultural crops, and also tie neatly in to your existing CS skill set with regard to agricultural SCADA (Supervisory Control and Data Acquisition), or Industrial Arduino as I like to call it.
Working for seed processes / distributors and fertiliser and pest & weed control industries could also be another foot-in-the-door move.
Botany comprises all, but most people see it as a synonym of plant classification.
Horticulture is about growing plants and multiplying it, often with flower power overtones and moon myths that vastly underestimate its importance.
Veganism is often mistaken as a synonym of "botany loving people", but is just a religious movement started by a priest, and centered around the random ideas that:
1) Plants occupy a lower rank of importance among life beings because they lack a single particular type of sensor that only the cool animals have, and...
2) Plants are safe to eat, because they were designed by god for us
None of those ideas are validated by real facts. As people grows in the cozy comfort of their religious group they lose the capability to see the whole picture and turn into food zombies that move and hate just by inertia. You can show science here for weeks and weeks without finding a sign of intelligent life.
---------------
Many people stop here and will never heard about:
Geobotany. Be afraid, very afraid. This is what a cabal of Da Vincy code linguists would do in the dark to bring pain to the world.
Most people will be put off by it in seconds, by the strange words and tedious lists, but there is an unexpected reward at the end when all pieces fall in place. You will never see the wildlife in the same way.
And plant physiology, that is like a really good sci-fi book.
Very complicated, defiant, dealing with really futuristic problems, and with more "hit the coin" moments that Mario. Who would imagine that the future of the humanity is linked with the capability to huge organisms to do physical work that makes the stronger animal look like crap
With a lot of software getting eaten up I’m increasingly interested in biology. Seems like one of the later frontiers that could have massive benefits, and AI is really well suited to help us understand it.
True and also, the actual physical contact and results are absolute magic. Maybe we need to create a "computer scientists for botony" forum. I think that has legs.
Botany is great because the results are basically what I'd call magic. It's such beauty (and horror on occasion).
The marriage of CS and botany seems like a match made in heaven and just from writing these comments I've convinced myself that it's probably the most practical way to go forward in life.
Just about everything we experience in our lives is a constant distraction from the fact that biology and its mechanisms are the most interesting thing in our existence.
Have you considered computational biology? They are always looking for people. Knuth said a while back that biology has tons of open and useful problems left to be solved.
This goes against all previous research/measurements for actually tall trees (looks like they only considered up to 80m) and the fact that there are exactly zeros trees in the world taller than 130 meters [1]. Wide capillaries at the base, like stated in the article, don't seem to be related.
I agree it doesn't pass the sniff test (where are the 500 meter trees in the rainforests?) but I think it would make an excellent goal for molecularbiological and genetic engineering. We (our civilization) need to become much more skilled at that before we start editing the human germline, and we will inevitably want to edit the human germline eventually (or rather we are currently exhibiting great restraint in not doing so but I'm not sure how much longer that will last), and anyway thousand meter trees just sound like they would be really cool.
Sounds cool but for such experimentation you would want relatively fast experimental iterations to get anywhere, and this would take literal ages. You can play around with growth speed of course but that’s a different question and might be in some ways opposed to achieving height.
I don't think so. You don't have to reach the height limit just to iteratively develop the initial implementation of the pump system. A system that actively moves water would push it out the top so you've got an observable phenomenon to work with.
I’m sure there will be a ton of unexpected complexities that arise only when you are trying to push the limits, like in all engineering domains. And it’s all a highly interconnected system, you cannot expect to dramatically change the water flow without impacting others aspects.
I know it is quite distant, but from my experience in large-scale data engineering, 90% of the time goes in addressing subtle issues that can only be observed hours into a job, the rest of the issues are quickly resolved earlier. I am assuming that such complexities will be so much harder in physical systems, and even more so in biological systems.
In theory you can always have taller mountains if you just have a (exponentially!) wider base. But given all sorts of practical constraints, Earth mountains are pretty much limited to <10 km.
Mostly true on Earth, but not on other planets with lower gravity, and AFAIK it depends on the rock type. Hence why you have Olympus Mons on Mars (or insanely tall ice mountains on Pluto, when that material couldn't form such a steep talus angle on Earth).
Which would also serve as reasonable challenges for genetic and molecularbiological engineering so ... what's your point?
Or do you mean to suggest that the failure of any accepted tree height records to surpass the maximum capillary distance can be explained by some other factor? (Based on your other comment it seems safe to assume that isn't what you meant but anyhow.) That seems far too convenient given that the observed cutoff is within the expected range.
"The placard recorded that the Nooksack tree produced 96,345 board feet (227.348 cubic meters) of the "finest quality" lumber.
The New York Times regarded the tree in a March 7, 1897 issue as the "most magnificent fir tree ever beheld by human eyes" and called its destruction a "truly pitiable tale" and a "crime".
The Morning Times of February 28, 1897 claimed that the wood, sawed into one-inch strips, would reach from "Whatcom [the tree's location] to China"."
to be fair, without humans there would be nobody to declare "barbarism". At one time, all humans were barbarians, it took a certain level of cultural development before the word "barbarism" was necessary, so at that point it was "new". It remains be be shown whether cultures that call other cultures "barbaric" are actually "better".
Barbarism was just the ethnic slang Greeks had for non Greeks that Romans then adopted for non Romans. But cultures playing “I’m the best” is not new nor did it require cultural development; othering is a natural part of game theory to make sure your tribe has tighter cohesion against intruders.
There are stories that the moss on trees in temperate rainforests allow the tree to pull water from their branches instead of the ground, increasing their max height.
For a while there were people poaching the moss that facilitated this, which is a problem because it grows only inches per year.
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”.
If you think of it that way, you have a real problem. It only takes about 10 meters for the weight of a column of water to create enough downward force that it starts vaporizing, at which point no pumping action works. This is why any deep well has a submerged pump. You simply can't pull water upward further than that with negative pressure in the Earth's atmosphere. It must be pushed with positive pressure instead.
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.
The trick for trees is capillaries, which change the equation. The 10 meter limit only applies to larger columns. With capillaries there's a high negative tension that allows evaporation from leaves to pull the xylem sap up 100 meters or more.
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.
One of the things Susan Simard proved was that deep rooted trees that had found subterranean water continue pulling that water at full speed at night when transpiration is low, and that water finds its way into the fungal networks in the soil and into nearby plants.
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.
I don't understand how osmosis enters into this? Capillary action is sufficient to explain water traveling up the roots to a point where it was removed. Evaporation from leaves is sufficient to explain removal during the day. You'd need some other explanation for extraction by fungi or etc at night.
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.
The 10 metre thing assumes you have a suction side which is 10 metres lower than the pump, or at least a suction that is long/low enough that it can’t meet the pump’s NPSHr (Net Positive Suction Head required).
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.
This line of reasoning has always cracked me up. The internal dialog acidentally out loud at the least flattering moment. I believe the correct response to be:
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?
That analysis only applies to a single discreet pump. A line of pumps in series does not suffer from that problem and that is roughly what a biological system would be expected to consist of.
There are no pumps in a tree, in series or not. There’s nothing between the roots and leaves that actively drives water upward in any way. The xylem is literally dead tissue.
Please notice that the comment I was responding to there made claims of physical infeasibility that I was responding to. I was not expressing any claims regarding actual concrete trees that you could go and visit.
More generally you seem to be dismissing out of hand the primary topic of discussion which is neither constructive nor enlightening.
Yeah, that "extreme low pressure" part of the article had me scratching my head. Even a complete vacuum at the top will not suck water up more than 10 meters! The author was probably oversimplifying for a lay audience.
Capillary action is subject to the same limits as suction at the top. Capillary action can't increase the water pressure at the bottom of the tree.
If you put a straight thin capillary tube upright in water so it sucks up water from the bottom, no matter how thin, it can't draw water up above ~10m of water level.
the research is relevant to the issue of transpiration column hieght as a postulated limitation to overall hieght of any tree.
a column of water is pulled by hydrogen bonding between molecules in a tug of war fashion, the top of the column is where water is dissociated from the column at such a rate as to maintain low pressure with respect to the column[xylem]
in summary water moves from bottom to top in a transpiration stream, that ultimately ejects water vapour from the leaves, resulting in a low efficiency mechanism, that loses a lot of the water but occurs at such a rate that the low efficiency is "good enough" for whats needed.
> a transpiration stream, that ultimately ejects water vapour from the leaves
I don't believe this is correct, or rather is not a required component of the system but rather incidental. The chemical system within the leaf removes water via chemical reaction. There is a respiration process to dispose of waste gasses. Water vapor happens to be lost to this process not of necessity but rather because keeping it separate is quite difficult (ie requires significant complexity and additional energy expenditure). I expect that many desert adapted species approach perfection (but have not bothered to verify).
Not sure if you’ve ever visited the groves in California where these huge trees grow but they seem to find the place where the wind doesn’t really seem to bother them, among other reasons (fog staying and little creeks terminating are others). And when the wind comes along it’s surprising how little they actually wave. Such tiny radii change I reckon cannot move much water like you’d need for a pumping notion. So I’d say it has barely if any an influence
Maybe it's not more trouble pumping, eh, sucking water up. But that the top branches are the last ones to get water in periods of draught, and have therefore more resilience?
Similarly, it blows my mind that all trees are made of air, specifically the carbon in it. I used to think that the biomass must come from the soil, but reality is more interesting.
There’s also a theory that the moss on these trees is mutualism instead of simply epiphytic. The moss holds moisture, which can be accessed by the tree.
While admittedly contested and only reproduced by a few labs outside Gerald Pollack's at University of Washington, there is a solid case that it could play a role in transporting water and sap to the tops of trees. At least, it's involved in the motion induced in hydrophilic tubes when there is sufficient ambient radiant energy (uv/infrared).
Schurr, J.M. (2013). Phenomena associated with gel–water interfaces: analyses and alternatives to the long-range ordered water hypothesis. J. Phys. Chem. B, 117(25), 7653–7674. https://doi.org/10.1021/jp302589y
Elton, D.C., Spencer, P.D., Riches, J.D. & Williams, E.D. (2020). Exclusion zone phenomena in water — a critical review of experimental findings and theories. Int. J. Mol. Sci., 21(14), 5041. https://doi.org/10.3390/ijms21145041 (open access; the most thorough critical review)
Elton, D.C. & Spencer, P.D. (2021). Pathological water science — four examples and what they have in common. In Water in Biomechanical and Related Systems (Biologically-Inspired Systems, vol. 17), pp. 155–170. Springer. https://doi.org/10.1007/978-3-030-67227-0_8 (preprint: https://arxiv.org/abs/2010.07287)
I regretably didnt save it but there was a truly hilarious topic on usenet sci.physics long long ago. If we've gathered enough evidence against something or if the thing goes against accepted consensus you are forbidden from doing further research and new evidence is no longer allowed. The topic then invited others to list such topics. The list grew to hundreds of entries and people couldnt resist getting angry reading their personal trigger words despite there being many more silly things on it.
Be careful with that dismissal. The concept of an exclusion zone itself appears to be legitimate. More generally, there's lots of strange and surprising effects that crop up on the molecular level at interfaces in solution. However not all mechanistic explanations for such behavior are shall we say "widely accepted".
And then there's homeopathy which is a largely unrelated and entirely nonsensical thing.
I don't get why it is believed that trees can't pump water above a certain limit, all it should take is a system of valves, something that plants already have for other purposes. It certainly isn't lumuted by trees literally sucking water up as that would limit them to a height that can be easily exceeded by the majority of trees.
It seems that trees just don't grow that tall anymore. Even common trees such as the spruce seem to be able to reach 100m, they just kind of don't.
One possibility is the depletion of nutrients. But what I think is to blame is the lack of elephants. They constantly ruined young trees and the lucky few that survived then grew huge. Perhaps the redwoods were actually created by the natives, who removed young trees, and kept the old trees standing.
Another paper for the “Obviously” category. Otherwise the leafs at the top would be brown. But I did a PhD myself and our papers were exactly the same. Noone wants to rock the boat. Professors just want to get to their pension without problems. And people will cite things that are in line with their own stuff. So there you have it. Just proving the obvious time and time and time again.
> These vessels have evolved intricate adaptations that can maintain the water in liquid form, even under the extreme low pressures
This sentence undersells the phenomenon quite a bit: the “extreme low pressure” is in fact several bars of negative pressure and the challenge of maintaining water in liquid form is avoiding cavitation.
I was exposed to the physics of trees though the entrance exam to École Polytechnique (France's best University) and it's been carved in my mind since then: http://alainrobichon.free.fr/Concours/X_PC_PH1_01.pdf
AFAIK students are still being given this masterpiece for practice even though it's now 25 years old.
I grow marijuana and chillies from time to time. I got good at it. I will say that plants are malleable in untold ways and so I find this article to be unsurprising.
Plants will do what they need to do in the end. I've done stuff like co2 bombing, and increasing nutrients to the point to where I get a whole new ecosystem of insects and an entirely new situation.
It is such fascinating stuff that it's actually the life I want to live. I'm a computer scientist but now I yearn for the botanical sciences.
I highly recommend checking out defoliation strategies and low-stress training methods for anyone interested. Plants are not dumb creatures. The results you can get from them are astonishing and the science of what plants actually are becomes more profound by the day.
I'm studying for a bachelor's degree in horticulture part-time through a distance-learning university. If you're more interested in growing plants, I'd say horticulture is a better fit than botany. If you're more interested in understanding how plants work, botany is probably the better choice. That said, you'll still learn a lot of botany in a horticulture degree as well obviously
Thank you sir. I actually got my CS from distance learning and somehow the combination of growing things and monitoring everything using CS just grabs me. I would work on any farm anywhere with appropriate agency.
Oooo, I get a bit excited about interdisciplinary techno-plant-and-livestock
Another area that might be easier to break in to as far as work goes is labouring for an irrigation business, kinda agricultural plumbing.
You’ve probably seen pivots[1] and side-roll irrigation systems.
This would put you in more direct contact with the farm operators, expose you to a wide range of agricultural crops, and also tie neatly in to your existing CS skill set with regard to agricultural SCADA (Supervisory Control and Data Acquisition), or Industrial Arduino as I like to call it.
Working for seed processes / distributors and fertiliser and pest & weed control industries could also be another foot-in-the-door move.
https://en.wikipedia.org/wiki/Center-pivot_irrigation
this is low key one of the few things that I think of doing for the rest of my life, though my bias is towards seaweed farming and related ecosystems
Botany comprises all, but most people see it as a synonym of plant classification.
Horticulture is about growing plants and multiplying it, often with flower power overtones and moon myths that vastly underestimate its importance.
Veganism is often mistaken as a synonym of "botany loving people", but is just a religious movement started by a priest, and centered around the random ideas that:
1) Plants occupy a lower rank of importance among life beings because they lack a single particular type of sensor that only the cool animals have, and...
2) Plants are safe to eat, because they were designed by god for us
None of those ideas are validated by real facts. As people grows in the cozy comfort of their religious group they lose the capability to see the whole picture and turn into food zombies that move and hate just by inertia. You can show science here for weeks and weeks without finding a sign of intelligent life.
---------------
Many people stop here and will never heard about:
Geobotany. Be afraid, very afraid. This is what a cabal of Da Vincy code linguists would do in the dark to bring pain to the world.
Most people will be put off by it in seconds, by the strange words and tedious lists, but there is an unexpected reward at the end when all pieces fall in place. You will never see the wildlife in the same way.
And plant physiology, that is like a really good sci-fi book.
Very complicated, defiant, dealing with really futuristic problems, and with more "hit the coin" moments that Mario. Who would imagine that the future of the humanity is linked with the capability to huge organisms to do physical work that makes the stronger animal look like crap
one time, while communing with Nature, I looked up at the transpiring coastal tree line flexing in the wind and I uttered, "pumps."
My hunch is that torsion, flex and their effect on the capillary structures are at play, but I haven't been able to step away from CS myself.
With a lot of software getting eaten up I’m increasingly interested in biology. Seems like one of the later frontiers that could have massive benefits, and AI is really well suited to help us understand it.
True and also, the actual physical contact and results are absolute magic. Maybe we need to create a "computer scientists for botony" forum. I think that has legs.
Botany is great because the results are basically what I'd call magic. It's such beauty (and horror on occasion).
The marriage of CS and botany seems like a match made in heaven and just from writing these comments I've convinced myself that it's probably the most practical way to go forward in life.
Just about everything we experience in our lives is a constant distraction from the fact that biology and its mechanisms are the most interesting thing in our existence.
But but… physics—space and time etc?
— Carl Sagan
Absolutely this.
There is apparently such a thing as "Computational Botany", where you model virtual plants.
Have you considered computational biology? They are always looking for people. Knuth said a while back that biology has tons of open and useful problems left to be solved.
[dead]
This goes against all previous research/measurements for actually tall trees (looks like they only considered up to 80m) and the fact that there are exactly zeros trees in the world taller than 130 meters [1]. Wide capillaries at the base, like stated in the article, don't seem to be related.
[1] https://www.sfgate.com/science/article/REDWOODS-How-tall-can...
I agree it doesn't pass the sniff test (where are the 500 meter trees in the rainforests?) but I think it would make an excellent goal for molecularbiological and genetic engineering. We (our civilization) need to become much more skilled at that before we start editing the human germline, and we will inevitably want to edit the human germline eventually (or rather we are currently exhibiting great restraint in not doing so but I'm not sure how much longer that will last), and anyway thousand meter trees just sound like they would be really cool.
Sounds cool but for such experimentation you would want relatively fast experimental iterations to get anywhere, and this would take literal ages. You can play around with growth speed of course but that’s a different question and might be in some ways opposed to achieving height.
I don't think so. You don't have to reach the height limit just to iteratively develop the initial implementation of the pump system. A system that actively moves water would push it out the top so you've got an observable phenomenon to work with.
I’m sure there will be a ton of unexpected complexities that arise only when you are trying to push the limits, like in all engineering domains. And it’s all a highly interconnected system, you cannot expect to dramatically change the water flow without impacting others aspects.
I know it is quite distant, but from my experience in large-scale data engineering, 90% of the time goes in addressing subtle issues that can only be observed hours into a job, the rest of the issues are quickly resolved earlier. I am assuming that such complexities will be so much harder in physical systems, and even more so in biological systems.
There are obviously other factors limiting tree growth, like compressive strength.
I seem to recall for some long-ago course that the 8,000m peaks are up around the compresssive limit so yoou couldn't really have a taller mountain.
In theory you can always have taller mountains if you just have a (exponentially!) wider base. But given all sorts of practical constraints, Earth mountains are pretty much limited to <10 km.
Mostly true on Earth, but not on other planets with lower gravity, and AFAIK it depends on the rock type. Hence why you have Olympus Mons on Mars (or insanely tall ice mountains on Pluto, when that material couldn't form such a steep talus angle on Earth).
Well, yes, I'm talking about ~1g on earth. And, also yes, rock type makes a difference but I assume there is some commonality with the tallest peaks.
Which would also serve as reasonable challenges for genetic and molecularbiological engineering so ... what's your point?
Or do you mean to suggest that the failure of any accepted tree height records to surpass the maximum capillary distance can be explained by some other factor? (Based on your other comment it seems safe to assume that isn't what you meant but anyhow.) That seems far too convenient given that the observed cutoff is within the expected range.
I was referring to your "500m trees" which would be over 3x taller than the tallest trees ever seen.
> 500m
500ft is taller than the max ever, not 1640 ft
Couldn't both things be true? Water transport is not the limiting factor, but some other thing is?
Kurzgesagt has two videos on trees addressing this and other questions.
https://m.youtube.com/watch?v=ZSch_NgZpQs
https://m.youtube.com/watch?v=pHJIhxZEoxg
The largest tree on record is rejected in part because it's over the theoretical limit: https://en.wikipedia.org/wiki/Nooksack_Giant
Too bad we cut it down, along with almost every other giant Douglas-fir.
Human barbarism is not new...
"The placard recorded that the Nooksack tree produced 96,345 board feet (227.348 cubic meters) of the "finest quality" lumber.
The New York Times regarded the tree in a March 7, 1897 issue as the "most magnificent fir tree ever beheld by human eyes" and called its destruction a "truly pitiable tale" and a "crime".
The Morning Times of February 28, 1897 claimed that the wood, sawed into one-inch strips, would reach from "Whatcom [the tree's location] to China"."
>Human barbarism is not new...
to be fair, without humans there would be nobody to declare "barbarism". At one time, all humans were barbarians, it took a certain level of cultural development before the word "barbarism" was necessary, so at that point it was "new". It remains be be shown whether cultures that call other cultures "barbaric" are actually "better".
Yeah man if a barbarian fells a tree in the forest but nobody is around to hear it, is it still barbaric?
Barbarism was just the ethnic slang Greeks had for non Greeks that Romans then adopted for non Romans. But cultures playing “I’m the best” is not new nor did it require cultural development; othering is a natural part of game theory to make sure your tribe has tighter cohesion against intruders.
Yeah, they were called barbarians because they talked funny. Bar bar barbar bar, they went.
Maybe they were talking about https://en.wikipedia.org/wiki/Barbara%27s_Rhubarb_Bar
...and if you aren't pronouncing it "Var" you might be one ;-)
This is such a useless comment. What even is your point?
There are stories that the moss on trees in temperate rainforests allow the tree to pull water from their branches instead of the ground, increasing their max height.
For a while there were people poaching the moss that facilitated this, which is a problem because it grows only inches per year.
God that's sad. We really can't have anything nice.
It’s harder to remove the moss from high up in the tree and there are more risks in doing so. I was never clear on how prevalent this shittery was.
Who wants moss!? Is it luxury moss?
When peeled off the trunk it comes off in sheets, which is a bit harder to accomplish than just creating tufts and blobs of moss.
Yes, for terrariums
I just visited this beauty[1] a few weeks ago. Not 400ft tall, but over half that and over 13ft round at the base!
We're lucky to have a handful of big Doug Firs, Sitka Spruce, and Western Red Cedars left on Vancouver Island.
[1]: https://en.wikipedia.org/wiki/Big_Lonely_Doug
>Giant trees have no trouble pumping water to top branches
Hm, may be because they are not really "pumping" the water?
What would you call it?
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”.
If you think of it that way, you have a real problem. It only takes about 10 meters for the weight of a column of water to create enough downward force that it starts vaporizing, at which point no pumping action works. This is why any deep well has a submerged pump. You simply can't pull water upward further than that with negative pressure in the Earth's atmosphere. It must be pushed with positive pressure instead.
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.
The trick for trees is capillaries, which change the equation. The 10 meter limit only applies to larger columns. With capillaries there's a high negative tension that allows evaporation from leaves to pull the xylem sap up 100 meters or more.
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.
One of the things Susan Simard proved was that deep rooted trees that had found subterranean water continue pulling that water at full speed at night when transpiration is low, and that water finds its way into the fungal networks in the soil and into nearby plants.
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.
I don't understand how osmosis enters into this? Capillary action is sufficient to explain water traveling up the roots to a point where it was removed. Evaporation from leaves is sufficient to explain removal during the day. You'd need some other explanation for extraction by fungi or etc at night.
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.
The 10 metre thing assumes you have a suction side which is 10 metres lower than the pump, or at least a suction that is long/low enough that it can’t meet the pump’s NPSHr (Net Positive Suction Head required).
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.
>if the tree were in a closed system with no solar input
... that would be the least of the tree's problems.
This line of reasoning has always cracked me up. The internal dialog acidentally out loud at the least flattering moment. I believe the correct response to be:
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?
Well, if you chop it down and burn it to boil water, then Use it to spin up a turbine…
It’s like the pop sci fact that if you took all your blood vessels and laid them end to end… you would die.
That analysis only applies to a single discreet pump. A line of pumps in series does not suffer from that problem and that is roughly what a biological system would be expected to consist of.
There are no pumps in a tree, in series or not. There’s nothing between the roots and leaves that actively drives water upward in any way. The xylem is literally dead tissue.
Please notice that the comment I was responding to there made claims of physical infeasibility that I was responding to. I was not expressing any claims regarding actual concrete trees that you could go and visit.
More generally you seem to be dismissing out of hand the primary topic of discussion which is neither constructive nor enlightening.
Yeah, that "extreme low pressure" part of the article had me scratching my head. Even a complete vacuum at the top will not suck water up more than 10 meters! The author was probably oversimplifying for a lay audience.
Yeah it's the difference between creating low vs high pressure.
The low pressure is up there already, for free.
Or the high pressure is down here, whichever way you want to look at it.
more like capillary action.
https://en.wikipedia.org/wiki/Xylem#Cohesion-tension_theory
Capillary action is subject to the same limits as suction at the top. Capillary action can't increase the water pressure at the bottom of the tree.
If you put a straight thin capillary tube upright in water so it sucks up water from the bottom, no matter how thin, it can't draw water up above ~10m of water level.
Oh, so we don't really know how it works. Fun.
the research is relevant to the issue of transpiration column hieght as a postulated limitation to overall hieght of any tree.
a column of water is pulled by hydrogen bonding between molecules in a tug of war fashion, the top of the column is where water is dissociated from the column at such a rate as to maintain low pressure with respect to the column[xylem]
in summary water moves from bottom to top in a transpiration stream, that ultimately ejects water vapour from the leaves, resulting in a low efficiency mechanism, that loses a lot of the water but occurs at such a rate that the low efficiency is "good enough" for whats needed.
> a transpiration stream, that ultimately ejects water vapour from the leaves
I don't believe this is correct, or rather is not a required component of the system but rather incidental. The chemical system within the leaf removes water via chemical reaction. There is a respiration process to dispose of waste gasses. Water vapor happens to be lost to this process not of necessity but rather because keeping it separate is quite difficult (ie requires significant complexity and additional energy expenditure). I expect that many desert adapted species approach perfection (but have not bothered to verify).
Capillary action and mechanical pumping by wind.
They do wave in the wind, and evolution is likely capturing some of that motion for work.
Not sure if you’ve ever visited the groves in California where these huge trees grow but they seem to find the place where the wind doesn’t really seem to bother them, among other reasons (fog staying and little creeks terminating are others). And when the wind comes along it’s surprising how little they actually wave. Such tiny radii change I reckon cannot move much water like you’d need for a pumping notion. So I’d say it has barely if any an influence
“Trees contain lots of thin, hollow vessels and they suck water upwards by creating low pressure at the top,”
So sucking / pulling?
So a suction pump?
Same principle as chimneys. But I also noticed this line:
> leaves which have adapted to withstand greater water stress before wilting.
That must be one of the "adjustments to water transport" mentioned. So I suggest that they do, in fact, have trouble pumping water to top branches.
Maybe it's not more trouble pumping, eh, sucking water up. But that the top branches are the last ones to get water in periods of draught, and have therefore more resilience?
Or, it’s simply a rate to variably adjust to, so the tree is neither flooding nor parching the leaf.
My recollection is that capillary action is a little from column a and a little from column b.
on the other hand, many giant trees get the water out of the air via fog:
Coalescence of coastal fog accounts for a considerable part of the trees' water needs.[23]
https://en.wikipedia.org/wiki/Sequoia_sempervirens#Fog_and_f...
https://en.wikipedia.org/wiki/Sequoia_sempervirens
Similarly, it blows my mind that all trees are made of air, specifically the carbon in it. I used to think that the biomass must come from the soil, but reality is more interesting.
Kind of like how the vast majority of weight loss in animals happens via exhaling.
Weirder still is the realization that all the air is just trapped light.
Actually, all matter is just trapped energy.
There is no such thing as energy.
Rather, no such thing as matter. Energy is pervasive.
It's also kind of weird to think that soil, really, is just ground up "stuff" that used to be trees, plants, rocks, etc.
Sequoia are still limited in height by gravity, probably due to capillary pressures. [1] If they evolved to be segmented, they could probably do it.
[1] https://www.sfgate.com/science/article/REDWOODS-How-tall-can...
There’s also a theory that the moss on these trees is mutualism instead of simply epiphytic. The moss holds moisture, which can be accessed by the tree.
Folks still sleeping on structured water.
While admittedly contested and only reproduced by a few labs outside Gerald Pollack's at University of Washington, there is a solid case that it could play a role in transporting water and sap to the tops of trees. At least, it's involved in the motion induced in hydrophilic tubes when there is sufficient ambient radiant energy (uv/infrared).
Relevant papers:
"Exclusion-zone water inside and outside of plant xylem vessels." 2024 Scientific Reports. https://www.nature.com/articles/s41598-024-62983-3
"Surface-induced flow: a natural microscopic engine using infrared energy as fuel." 202 Science Advances. https://www.science.org/doi/10.1126/sciadv.aba0941
"Long-range forces extending from polymer-gel surfaces." 2003 Phys. Rev. E. https://link.aps.org/doi/10.1103/PhysRevE.68.031408
Pollack's site: https://www.pollacklab.org/
Some critiques of Pollack's theory:
Schurr, J.M. (2013). Phenomena associated with gel–water interfaces: analyses and alternatives to the long-range ordered water hypothesis. J. Phys. Chem. B, 117(25), 7653–7674. https://doi.org/10.1021/jp302589y Elton, D.C., Spencer, P.D., Riches, J.D. & Williams, E.D. (2020). Exclusion zone phenomena in water — a critical review of experimental findings and theories. Int. J. Mol. Sci., 21(14), 5041. https://doi.org/10.3390/ijms21145041 (open access; the most thorough critical review) Elton, D.C. & Spencer, P.D. (2021). Pathological water science — four examples and what they have in common. In Water in Biomechanical and Related Systems (Biologically-Inspired Systems, vol. 17), pp. 155–170. Springer. https://doi.org/10.1007/978-3-030-67227-0_8 (preprint: https://arxiv.org/abs/2010.07287)
I regretably didnt save it but there was a truly hilarious topic on usenet sci.physics long long ago. If we've gathered enough evidence against something or if the thing goes against accepted consensus you are forbidden from doing further research and new evidence is no longer allowed. The topic then invited others to list such topics. The list grew to hundreds of entries and people couldnt resist getting angry reading their personal trigger words despite there being many more silly things on it.
Yours shall be filed under homeopathy :)
Be careful with that dismissal. The concept of an exclusion zone itself appears to be legitimate. More generally, there's lots of strange and surprising effects that crop up on the molecular level at interfaces in solution. However not all mechanistic explanations for such behavior are shall we say "widely accepted".
And then there's homeopathy which is a largely unrelated and entirely nonsensical thing.
I don't get why it is believed that trees can't pump water above a certain limit, all it should take is a system of valves, something that plants already have for other purposes. It certainly isn't lumuted by trees literally sucking water up as that would limit them to a height that can be easily exceeded by the majority of trees.
It seems that trees just don't grow that tall anymore. Even common trees such as the spruce seem to be able to reach 100m, they just kind of don't.
One possibility is the depletion of nutrients. But what I think is to blame is the lack of elephants. They constantly ruined young trees and the lucky few that survived then grew huge. Perhaps the redwoods were actually created by the natives, who removed young trees, and kept the old trees standing.
> all it should take is a system of valves,
That would work, but it's not how to works apparently. According to this veritasium video, it's because of "negative pressure" aka tension.
https://www.youtube.com/watch?v=BickMFHAZR0
I recommend watching, I think it's one of the best veritasium Dereck has ever produced.
Also, wasn’t the 250 ppm atmospheric CO2 concentration prior to the start of the Industrial Revolution a historic low as far a geological-time goes?
I suppose that’s not particularly relevant for more recent old growth tall trees that seem to have got by fine in a colder Earth.
But it’s easy to imagine a warmer, wetter, Earth with higher atmospheric CO2 concentrations being more conducive to taller tree growth.
On the other hand, I probably don’t really know what I’m talking about, not my area of expertise.
plants are very brave, both metaphorically and physically.
Another paper for the “Obviously” category. Otherwise the leafs at the top would be brown. But I did a PhD myself and our papers were exactly the same. Noone wants to rock the boat. Professors just want to get to their pension without problems. And people will cite things that are in line with their own stuff. So there you have it. Just proving the obvious time and time and time again.
“The root cause is nailed down (not a theory anymore)…” —Claude
Any truth to whether water pumped by tree (branches) is potable?
I’m glad to find the trees are doing well, even the big ones, that managed to grow big... ???
Happy for them.
This made me laugh out loud. Thanks.
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