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Author Topic: How do Trees Really lift Water to their Leaves?  (Read 245035 times)

lyner

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Re: How do Trees Really lift Water to their Leaves?
« Reply #325 on: 12/07/2009 22:21:09 »
AKF
Why do you introduce a nonsense question about why trees "bother" to shed [edit] leaves.
If large leaves were not shed they would rupture in frost and let infection enter. Any connection with your theory is spurious (not for the first time).
« Last Edit: 13/07/2009 10:29:54 by sophiecentaur »
 

lyner

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Re: How do Trees Really lift Water to their Leaves?
« Reply #326 on: 13/07/2009 10:42:24 »
AFK
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A tree grows slowly and is filled with fluids from the onset so does not require fluids to be lifted to the leaves as per Sophies rope and bucket analogy

I just re-read this comment. Do you not see what rubbish it is? If a tree is 30m high, it GREW there. All materials needed to be lifted up there during the growing process. How long it took is irrelevant to the energy needed.

How can you expect to be taken seriously when you misunderstand elementary things like that?

If you accept that Energy is conserved in chemical and physical processes then you need to apply that principle in all of your ideas. You can't pick and choose what Science to use and what not to use. It's a consistent package - not mumbo jumbo, like your ideas.

 

Offline Andrew K Fletcher

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Re: How do Trees Really lift Water to their Leaves?
« Reply #327 on: 15/07/2009 20:32:30 »
Circulation of fluids is what counts as the tree grows, the tree maintains circulation using density changes caused by evaporation.

HOW ON EARTH CAN A TREE EVAPORATE WATER WITHOUT ALTERING THE DENSITY OF THE SAP inside the leaves and branches? does the tree somehow magically whisp the density away? Does it someohow suck sufficient water in from the atmosphere to replace the water it loses?

If 98% of all the water drawn through the roots evaporates through the leaves and the water inside the leaves contains a solution of sugar and salts surely some concentration of said salts and sugars will take place! Why have our learned bretheren overlooked something so blatantly obvious? Common sense lacking?

Easy question here...........



AFK
Quote
A tree grows slowly and is filled with fluids from the onset so does not require fluids to be lifted to the leaves as per Sophies rope and bucket analogy

I just re-read this comment. Do you not see what rubbish it is? If a tree is 30m high, it GREW there. All materials needed to be lifted up there during the growing process. How long it took is irrelevant to the energy needed.

How can you expect to be taken seriously when you misunderstand elementary things like that?

If you accept that Energy is conserved in chemical and physical processes then you need to apply that principle in all of your ideas. You can't pick and choose what Science to use and what not to use. It's a consistent package - not mumbo jumbo, like your ideas.


 

Offline BenV

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Re: How do Trees Really lift Water to their Leaves?
« Reply #328 on: 15/07/2009 22:27:00 »
Andrew.  Where do you think plants get the material from which to grow?
 

Offline Andrew K Fletcher

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Re: How do Trees Really lift Water to their Leaves?
« Reply #329 on: 16/07/2009 07:29:13 »
Andrew.  Where do you think plants get the material from which to grow?

From the dilute solution of nutrients in the soil, water from the atmosphere, sugars from photosynthesis and carbon dioxide and oxygen from the atmosphere. http://biology.clc.uc.edu/Courses/bio104/photosyn.htm A link to refresh your memory Ben :)

Almost forgot to add some trees use bacteria to draw nitrogen from the atmosphere.
« Last Edit: 16/07/2009 08:06:41 by Andrew K Fletcher »
 

Offline Andrew K Fletcher

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Re: How do Trees Really lift Water to their Leaves?
« Reply #330 on: 16/07/2009 07:31:35 »
Now
AKF
Why do you introduce a nonsense question about why trees "bother" to shed [edit] leaves.
If large leaves were not shed they would rupture in frost and let infection enter. Any connection with your theory is spurious (not for the first time).
who is being nonsensical? How does a tree know there is about to be frost? Does it watch the BBC weather forcast as the leaves fall long before the first frost in most cases? No what happens is that increased rainfall introduces far more water into the tree diluting the sap. Coupled with huge increases in humidity and damp together with colder air causes the circulation in the tree to slow down and at times to the point of circulatory arrest. Density changes are also slowed down by a huge reduction in sunlight so again sugar production slows down and evaporation rates also slow down. Density in the sap at the leaf is reduced by the migration of solutes and nutrients away from the source to a sink causing the leaves to change colour as the tree effectively washes the life out of the leaves. Take the same tree to a more temperate climate and it seldom sheds leaves.

http://www.thenakedscientists.com/forum/index.php?topic=18299.0%3Bprev_next=prev   Dentstudent answers a question on leaf shedding.
« Last Edit: 16/07/2009 07:47:23 by Andrew K Fletcher »
 

Offline Andrew K Fletcher

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Re: How do Trees Really lift Water to their Leaves?
« Reply #331 on: 16/07/2009 07:56:40 »
Interesting, so according to you, cellar walls which have a ruberoid coating or membrane on the outside and an equally waterproof coating on the inside ooze water out of the top of the membrane rather than the membrane preventing the water from entering the brickwork? I have observed this following a heavy rain by the way and attributed it to the water table level rising and water running down the outide of the building to the basement wall rather than water percolating up the membrane. Fascinating, though I must admit that a swimming pool provides an excellent example of retaining the water inside it and I have never noticed water oozing out of the soil around the outside and one would have thought this should happen based on your post content, although there may not be an external waterproof barrier on a pool. A lot of buildings do have a waterproof coating and rendered exterior.

Thinking of a way I can test your post experimentally. Though I suspect what you may be refering to is a form of evaporative sweating with condensation reaching the upper part of the coated walls. Not quite the same as active water transport but a valid point on reflection.



All answers welcome, here is a chance to do some "science"

Not literally but yes according to the tension theory if a brick evaporates water it should aslo apply the same tension to the water below so stacking one brick onto another should cause rising damp to travel to the tops of walls but it clearly does nothing of the kind.

If you cover the walls with a layer of waterproof material (I can't say I have tried tree bark- but it would be interesting) then that's exactly what happens. The water soaks up to the top and evaporates there.
Of course, without that cover, it evaporates before it reaches the top.
Scince is based on observation. My observation is that your assertion is false.
This tends to suport (though it does not prove) the opposite viewpoint.
In effect you have just proved your own ideas to be faulty.




All answers welcome, here is a chance to do some "science"

Not literally but yes according to the tension theory if a brick evaporates water it should aslo apply the same tension to the water below so stacking one brick onto another should cause rising damp to travel to the tops of walls but it clearly does nothing of the kind.
« Last Edit: 16/07/2009 08:32:59 by Andrew K Fletcher »
 

lyner

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Re: How do Trees Really lift Water to their Leaves?
« Reply #332 on: 16/07/2009 10:22:19 »
AKF
Quote
HOW ON EARTH CAN A TREE EVAPORATE WATER WITHOUT ALTERING THE DENSITY OF THE SAP . . . .
Did anyone say that it could? Of course there will be dense solutions at the top. The question is whether there is enough to provide the motive power mechanism you propose.

Quote
If 98% of all the water drawn through the roots evaporates . . . . . .
So you are implying that the 2%, falling can lift the 98% for transpiration? Fantastic. We have a brilliant new way of making skyscraper lifts work, for free.
You are still locked onto this circulation theory with not a single numerical reason to justify it. If the numbers don't tally, there must be another reason. But of course, Maths is just there in order to discredit  the unqualified, isn't it?

Quote
Easy question here
An easy question but no answer, apparently, from you.

Quote
How does a tree know there is about to be frost? Does it watch the BBC weather forcast as the leaves fall long before the first frost in most cases?
You discredit yourself here, yet again.  If a tree could react quickly enough to avoid the damage of a chance frost then that would be a great energetic advantage - it would not have to grow more leaves after a mild winter. The action has to be taken in order to be on the safe side and it gets its clues from day length and night temperatures. Evergreen trees which survive extreme cold have other strategies than dropping leaves. They are subjected to exactly the same rainfall etc. as their deciduous neighbours - why don't their leaves fall of, according to you? Take a tree to a different climate and it may well react differently - but, if a species is to survive, this reaction will still be 'on the safe side'. Many equatorial trees will die if you put them in an English garden with English frosts, despite the fact that they get the same rainfall as the native plants - they will not drop their leaves deciduously but suffer from 'leaf drop' through injury by the cold.
If the leaf shedding strategy were not to protect against frost then why does it not occur so much in warmer climates?  During the monsoon, for instance. Autumns in the Eastern Seaboard of the USA are dry but the leaves are still shed.
But I don't see why you even introduced this line of thought. It is very typical that you don't deal with an objection - you just divert the flow of the argument.

BTW, it would help a lot if you posted your quotes before your replies, rather than after them. You launch into a tirade before declaring what you object to.
 

Offline Bored chemist

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lyner

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Re: How do Trees Really lift Water to their Leaves?
« Reply #334 on: 17/07/2009 00:13:01 »
BC
That wiki page is not supported by references. There are better sources but few academic ones. I was looking.
 

Offline Andrew K Fletcher

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Re: How do Trees Really lift Water to their Leaves?
« Reply #335 on: 17/07/2009 09:37:53 »
Andrew,
http://en.wikipedia.org/wiki/Damp-proof_course

http://www.buildingpreservation.com/evaluating%20chemical%20dpcs2.htm here is a better one showing the level of rising damp. Not quite a hundred meters or more vertically and it does mention the salts from soil water being concentrated by evaporation.

From another source on rising damp.

The height to which the water will rise depends on
several factors including pore structure and rate of
evaporation. Masonry containing a high proporation of
fine pores will allow the water to rise higher than a coarse
pored material; basically the water is carried up the wall
in the finer pores and not those of large diameter. The
average size of pores in masonry gives a theoretical rise
of around 1.5 meters but where evaporation is severely
retarded, for example by the use of impervious
membranes, moisture can sometimes rise in excess of
2 metres.

capilary action was discussed earlier in this thread and the flow rates observed in trees could not be addressed, neither could the height of trees be considered when using capillary action. And the final objection is the dependency on capillary action of the diameter of the vessels. The diameter of the tubular cells in trees is often much greater than the fine capillary tubes used to demonstrate even a modest lift.

I have been photographing some tall trees that have a relatively few leaves yet appear to draw water from the ground for many years and are unaffected by their inherant lack of leaves.

How can the cohesion tension "hypothesis" address this serious and obvious flaw? Quite clearly it sucks in more than one aspect. I await your reply in it's defence.

« Last Edit: 17/07/2009 16:46:51 by Andrew K Fletcher »
 

Offline rosy

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Re: How do Trees Really lift Water to their Leaves?
« Reply #336 on: 17/07/2009 11:03:56 »
How can your theory that all drawing of water from the ground requires evaporation at the leaves to provide a density flow address this serious and obvious flaw?
 

lyner

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Re: How do Trees Really lift Water to their Leaves?
« Reply #337 on: 17/07/2009 17:52:35 »
AFK
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some tall trees that have a relatively few leaves yet appear to draw water from the ground for many years and are unaffected by their inherant lack of leaves.
Do you purposely go for the non-sequeter every time?
Fewer leaves means less transpiration, which means less water is drawn up per hour.  Each leaf transpires one leaf's worth of water. What has "for many years" got to do with it?

I understand that the capillary action idea may not be satisfactory but why does that mean that yours is anything like a viable alternative?

You have avoided, as usual, a very important question applying to your idea. How much water goes up and how much water goes down? How can such a small amount of water going down provide lift for so much going up? Doesn't mechanics work in your world? Don't all the sums about energy and work mean anything to you - and I mean quantitatively, not armwavingly?
If I said that the bicycle chain going round makes your legs move as well as the wheels, I suspect that you would say I was daft. What you are saying is the equivalent of that.
 

Offline Andrew K Fletcher

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Re: How do Trees Really lift Water to their Leaves?
« Reply #338 on: 23/07/2009 12:23:33 »
Show us how a few leaves can suck water up tubes stretching a hundred metres when we struggle to suck water up a tube a metre high.

Explain how the buds get water delivered to them when there is not a single leaf on a tree?

Explain Strasburger's observations with circulation taking place for several weeks in a tree that has every single living process killed by introducing picric acid into it at a severed trunk immersed in a bath full of the stuff.

I repeat the Cohesion tension hypothesis sucks and is nonsense and deserves it’s rightful place deep within a fictional blackhole.

Nice try on the rising damp but one that has been put forward several times over the years and in this thread capillary action was debunked as it could not address the diameters of the tubes involved and the flow rates observed, let alone the heights achieved by trees..




AKF
Quote
HOW ON EARTH CAN A TREE EVAPORATE WATER WITHOUT ALTERING THE DENSITY OF THE SAP . . . .
Did anyone say that it could? Of course there will be dense solutions at the top. The question is whether there is enough to provide the motive power mechanism you propose.

Well yes someone has said the density changes will not take place because more water will arrive to re-dilute it and take it’s place. This of course does not prevent the change in density but merely supports a circulation theory rather than a redundant one way ticket to the atmosphere hypothesis.




Quote
If 98% of all the water drawn through the roots evaporates . . . . . .

Quote
So you are implying that the 2%, falling can lift the 98% for transpiration? Fantastic. We have a brilliant new way of making skyscraper lifts work, for free.
You are still locked onto this circulation theory with not a single numerical reason to justify it. If the numbers don't tally, there must be another reason. But of course, Maths is just there in order to discredit  the unqualified, isn't it?

Well it appears to work for the Californian Redwoods and a few other magnificent specimens towering well over a hundred metres. Did anyone observe a mechanical lift used in their construction?
 

Offline BenV

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Re: How do Trees Really lift Water to their Leaves?
« Reply #339 on: 23/07/2009 12:44:20 »
Andrew, the current explanation may be inaccurate.

Right now, yours is a long way from being complete enough to even faintly threaten it.  Stop whinging and do the science.  Start with the sums, as sophie has been asking you to do for ages.

Until you do that, you're pissing in the wind.
 

lyner

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Re: How do Trees Really lift Water to their Leaves?
« Reply #340 on: 23/07/2009 15:13:36 »
AFK
You seem to have got your quotes in a twist in your last post. Just WHO said WHAT??

(As sloppy with your use of the square bracket as with your use of Science).

I am still waiting for some figures to back up your nonsense. Did the redwoods just appear there or did they have to ~GROW up to that height, carrying their materials with them? (Edit)
« Last Edit: 23/07/2009 16:53:33 by sophiecentaur »
 

Offline Bored chemist

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Re: How do Trees Really lift Water to their Leaves?
« Reply #341 on: 23/07/2009 19:53:55 »
BC
That wiki page is not supported by references. There are better sources but few academic ones. I was looking.
I grant that it's not supported by references but all I needed to do was show that there is some evidence that such things exist. If Andrew wanted to he could have searched elsewhere. I would, had he asked, have sugested that he looked at the walls of his own house.

This page
http://en.wikipedia.org/wiki/Mathematics
is quite well referenced and I wonder if we could explain its importance to Andrew.
 

lyner

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Re: How do Trees Really lift Water to their Leaves?
« Reply #342 on: 23/07/2009 21:21:23 »
BC.
It's just mumbo jumbo, you know. It's not repeatable and you have to be a professor to use it.
 

Offline _Stefan_

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Re: How do Trees Really lift Water to their Leaves?
« Reply #343 on: 24/07/2009 05:49:43 »
Why does AKF bother to post at all if he is unwilling to properly address critique?
 

lyner

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Re: How do Trees Really lift Water to their Leaves?
« Reply #344 on: 24/07/2009 20:38:17 »
I think he thrives on adverse criticism of his ideas. It saves him having to examine them too closely, himself, because he can. instead, get blindly defensive about them.

There's a lot of inverse technical snobbery there, I think.
 

Offline _Stefan_

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Re: How do Trees Really lift Water to their Leaves?
« Reply #345 on: 25/07/2009 06:58:05 »
Wonderful. And you can't ignore him either, lest people start taking him seriously.
 

Offline Andrew K Fletcher

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Re: How do Trees Really lift Water to their Leaves?
« Reply #346 on: 31/08/2009 13:49:46 »
Modeling xylem and phloem water flows in trees according to cohesion theory and münch hypothesis

HÖLTTÄ T. (1) ; VESALA T. (1) ; SEVANTO S. (1) ; PERÄMÄKI M. (2) ; NIKINMAA E. (2) ;

(1) Department of Physical Sciences, University of Helsinki, P.O. Box 64, 00014, FINLANDE
(2) Department of Forest Ecology, University of Helsinki, P.O. Box 24, 00014, FINLANDE
Abstract
Water and solute flows in the coupled system of xylem and phloem were modeled together with predictions for xylem and whole stem diameter changes. With the model we could produce water circulation between xylem and phloem as presented by the Münch hypothesis. Viscosity was modeled as an explicit function of solute concentration and this was found to vary the resistance of the phloem sap flow by many orders of magnitude in the possible physiological range of sap concentrations. Also, the sensitivity of the predicted phloem translocation to changes in the boundary conditions and parameters such as sugar loading, transpiration, and hydraulic conductivity were studied. The system was found to be quite sensitive to the sugar-loading rate, as too high sugar concentration, (approximately 7 MPa) would cause phloem translocation to be irreversibly hindered and soon totally blocked due to accumulation of sugar at the top of the phloem and the consequent rise in the viscosity of the phloem sap. Too low sugar loading rate, on the other hand, would not induce a sufficient axial water pressure gradient. The model also revealed the existence of Münch counter flow, i.e., xylem water flow in the absence of transpiration resulting from water circulation between the xylem and phloem. Modeled diameter changes of the stem were found to be compatible with actual stem diameter measurements from earlier studies. The diurnal diameter variation of the whole stem was approximately 0.1 mm of which the xylem constituted approximately one-third.
Revue / Journal Title
Trees   ISSN 0931-1890   CODEN TRESEY
Source / Source
2006, vol. 20, no1, pp. 67-78 [12 page(s) (article)] (43 ref.)
 

lyner

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Re: How do Trees Really lift Water to their Leaves?
« Reply #347 on: 31/08/2009 18:51:16 »
AKF
Very interesting but does it say anywhere that the whole thing is "driven by gravity", which is the claim you make and with which I (several of us) disagree? I don't think anyone has a problem with the idea that solutions flow around plants. I don't think you have posted anything to support the gravity idea, have you?
 

Offline Andrew K Fletcher

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Re: How do Trees Really lift Water to their Leaves?
« Reply #348 on: 31/08/2009 19:12:29 »
AFK
Quote
A tree grows slowly and is filled with fluids from the onset so does not require fluids to be lifted to the leaves as per Sophies rope and bucket analogy

I just re-read this comment. Do you not see what rubbish it is? If a tree is 30m high, it GREW there. All materials needed to be lifted up there during the growing process. How long it took is irrelevant to the energy needed.

How can you expect to be taken seriously when you misunderstand elementary things like that?

If you accept that Energy is conserved in chemical and physical processes then you need to apply that principle in all of your ideas. You can't pick and choose what Science to use and what not to use. It's a consistent package - not mumbo jumbo, like your ideas.



Your blinkered approach is limiting Sophie. Circulation of fluids is all that is required, not a one way indian rope trick but a gentle rotation of fluids where the downward flow provides an increase head of flow in the return / xylem side providing the impetus for vertical growth.

The paper abstract mentions circulation when transpiration has stopped. read it.
 

lyner

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Re: How do Trees Really lift Water to their Leaves?
« Reply #349 on: 04/09/2009 00:12:01 »
Blinkered or careful? My question was whether the reference supports your gravity idea. If it does then you could, perhaps, cut and paste the paragraph for us.
 

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Re: How do Trees Really lift Water to their Leaves?
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