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How do Trees Really lift Water to their Leaves?

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8 years 8 months ago #689 by Andrew
Witsend:

I'm very happy with altrnate theories but why try and improve on osmosis? Surely it explains everything? I'm not sure that ANYTHING need be added to this process. It's just that the roots can take up water and the leaves can give out water. Perfect illustration of the same principle with reversed applications.

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8 years 8 months ago - 8 years 8 months ago #690 by Andrew
Lyner:

The arguments for accepted explanations for fluid transport in trees has not been forthcoming, in fact this thread has shown they are indeed flawed.


AKF. Why are you resurrecting this?

So your argument is not flawed?
As a matter of fact, you have no scientific argument at all. You keep repeating purple passages and the quoting the same instances. Is there any new development in research since you last posted?
We established that, in your smooth tube, you could get a measurable effect from cohesion in water which was a surprise to me. I have accepted that it happened. But is does not explain where the energy comes from.

Your explanation ignores the rest of Science on the grounds that you are ignored due to lack of qualifications. The reason that I / we don't accept your explanation for the phenomenon is because it is not a scientific one. You are hanging it all on the idea of cohesion vs adhesion. However, the Science which applies everywhere else in the World is not allowed to act inside plants - according to you. Isn't Science supposed to be consistent?

Whilst we are 'imagining', lets discuss your circulatory model and use a simple mechanical model.
Take a long loop of rope hanging over a pulley at the top of a building. Tie buckets at regular intervals onto the rope. Fill each bucket with water and add some stones. The stones represent your dissolved salts.
The buckets are spaced equally on the rope, for a start. (This is a simple model, so you have to ignore the problem of getting the buckets over the pulley at the top if the rope moves around - but that could be solved, of course.)

As an analogy to your transport theory, some water and some of the rock leaves the topmost bucket - leaving it half full and with most of the rock in it. It is now lighter than all the other buckets. Manually pull one side of the rope down and half empty the next bucket and the next and the next, as they reach the top and go over. There is now an imbalance. One side of the rope has less load than the other which, left to itself, will pull the emptier buckets back up to the top and those full of water will fall back down. You won't get a circulation.
The only way that you can sustain the motion is for someone at the top to be putting more rocks into the buckets that you want to go down. To lift water constantly, you need fractionally more weight to be added on the other side - constantly.
In a plant, the only source of extra weight, up there with the leaves, is C from the CO2 from the air (during photosynthesis). Just do the sums - compare the mass of water lost during transpiration with the mass of food produced by photosynthesis. There are just not enough 'extra rocks' produced at the top to pull the required amount of water up in the buckets. As I have so often said -The Numbers Count!
I have avoided using the Energy word because you have ignored its use in the past. The above, very mechanical, model shows that your proposed system cannot work. Can you possibly have an argument against what I have written?

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Last edit: 8 years 8 months ago by Andrew.

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8 years 8 months ago #691 by Andrew
Not hanging it on the idea of cohesion versus adhesion, this argument was for the tubular experiments, which of course applies to the density flow theory also. Science is supposed to be consistent but it clearly is not when there are errors in the science!

You appear to be missing a huge chunk of information in your analogy. Let me try to clear it up for you.

Picture a 3 mil bore tube (for instance) as one ascending limb, in this case representing the phloem, which is predominantly downward flowing sap and has far more dissolved solutes in it than the predominantly ascending sap in the xylem vessels. (published science).

Now back to the tubular experiment which admittedly is a simplified model designed only to show the density flow and that cohesion and adhesion play a part in the experiment, although I suspect not an equal part, but let’s ignore this for now.

In our ascending tube we use say 6.5mm bore tubing and do not include any salt for the moment. We raise our unequal bore tube up to say 24 meters and we do not see a flow in either direction but a stagnation of water suspended inside both the 3 mil bore tube and the 6.5 mil bore tube. In fact we could probably show 2 tubes attached to one side and a single tube attached to the other side providing there is a smooth uninterrupted bore at the upper most part of the suspended tube. All ends are open to the atmosphere but suspended in a bottle or bottles filled with water and at equal levels with the ground.

Now, let us see how this fits with your rope and bucket analogy. Ok let’s ignore the buckets and rocks for now. If we had a rope that was the same diameter and the same molecular weight, the rope with careful positioning could indeed stay suspended as there would be an equal counterbalance.

But let’s add a rope twice the size and twice the weight on one side of the pulley. Of course we would see one side pulled down by gravity and the lighter rope side drawn up without any added weights.

In the experiment and inside the tree or plant, there is an equalizing fluid balance that takes away the need for raising the fluids or indeed suspending the fluids.

Unlike the simplified experiment the tree has a multi conduited system inside a larger conduit, the bark with its roots beneath the soil. This is important in this instance because like the bottles of water, it offers support for the columns due to the air soil and water pressure applied to the outside of the tree and more so to the roots.

Yet if we cut the roots off or indeed run a chainsaw through the multiconduited tree system we do not see water oozing out but the water inside retracts up the severed trunk, and this also happens when the ends of the tubes are pulled from the bottles while the water is suspended inside the inverted U tube.

Now back to the flow and return system. According to the above explanation and indeed observations, we can have several upward flowing xylem vessels that are counterbalanced by a ingle downward flowing phloem vessel (for arguments sake) This would give us a mechanism for shedding a huge volume of water at the leaves while returning a smaller yet denser volume down the phloem vessel. Again this experiment was conducted albeit a scaled down version of the Brixham Experiment. “ x ascending salt free and one descending tube attached at the centre which was raised to 2.5 metres. Result was that the flow and return continued to work regardless of the weight on either side of the inverted U tube.

The extra molecular weight at the leaf is not entirely relying on CO2. For example, a deciduous tree that has shed it’s leaves cannot rely on CO2 but somehow manages to circulate fluids to the emerging buds.

You have overlooked the nutrients and colloids from the soil, these are delivered to the leaves in dilute solution and MUST be concentrated by evaporation! Sugars are produced at the leaf from CO2 but cannot be produced if there are no leaves!

Inside the deciduous tree that has shed it’s leaves we have suspended sugars and salts, most of which migrate to the roots during the fall again verifying the need for gravity in any theory that addresses the ascent of sap in tall trees. All that would be required for circulation to continue is an unequal density in the sap and the warmth during the spring and summer provides an external heat / density change to the sap, sufficient to trigger an increase in circulation, but also an increase in positive pressure at the branches, providing the impetus for buds to emerge.

Yes I do have an argument, not against your work an motion analogy but against how you have applied it to a fluid based system.

Andrew

P.S. Yes there has been a huge development recently with regards to publication.

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8 years 8 months ago #692 by Andrew
Lyner:
So a few lines of total logic are answered with far too much verbiage to even read, let alone answer.
You have not answered the overwhelming fact that, somewhere, you have to produce an equal WEIGHT of falling water plus stuff (plus a little bit) to balance the amount of water you need to raise. (You would not argue against the idea of vast amounts of water being transpired, I presume) Whether you are discussing 20m or 1cm. Where do all these extra weights - ropes, salts etc. come from way up there in the tree? If you want to pull something up you need something to pull it down with. If you want the process to continue, according to your model, you keep needing extra weight added at the top. Where could it possibly come from? This is not Science - it's what a child with a construction kit would conclude. It could not work on that principle.
Can you really not understand that?

I wonder why I bother, sometimes.

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8 years 8 months ago #693 by Andrew
Try the "Bleeping" experiments before you jump to conclusions!

Listen to what has been said!

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8 years 8 months ago #694 by Andrew
Lyner:
We frequently find that alternate Science theories just change direction to suit rather than dealing with inconsistencies. If a molecule interacts chemically or mechanically with its neighbours in a particular way under one set of circumstances then, unless conditions are radically changed, we normally expect it to behave the same way in another set.
Just how the molecules are supposed to know they're in a tree and not in a tube beats me. Unless it's supposed to be the 'flow' that sustains the flow - being perpetual motion.

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8 years 8 months ago #695 by Andrew
Water is inside the tree during growth and the tree does not have to lift water to it's leaves because it is already at the leaf and if it is not then the leaf is desiccated and dies! No need to explain how a dead tree can suddenly decide it wants to pull water from the ground because it does not happen in nature. “Having said that I remember a Yucca Plant that died below completely yet somehow sent down a taproot through the dead trunk and began growing again.”

So if the fluids are suspended from ground level, all we need to show is how these fluids circulate by introducing a density pumping mechanism.

Here we have a density change caused by evaporation , which no one can argue against!

As molecules of denser solution are acted upon by gravity they have to migrate down the tree from a source to a sink and in doing so drag on all of the other sap molecules inducing not only a downward flow but a return flow. “for every action there is a reaction” The downward flow “source to sink” in a tree is located in the phloem. The sap in the phloem contains more dissolved solutes and is denser than the upward flowing xylem sap. If you can for a minute picture the beads of phloem sap as links in a chain around the branches and trunk of a tree it is not difficult to see how phloem in some parts of the tree can move against gravity as it is dragged around the circuit by the downward flowing denser sap.

We don’t need to show buckets with stones in them and rope as an analogy, it simply does not fit with the fluid model because the fluid model adapts to suit the different diameters of tubular cells within a tree.
I have mentioned before that the density changes in the ocean caused by evaporation and heat drive the Altlantic Conveyor System, an underwater river bigger than all the rivers in the World put together. In the ocean there are no vessels or tubular cells to obscure the density bulk flow.

In a domestic pump-less hot water system we can see a flow and return “copper pipes” This appears to behave the same as the ocean and does not rely on nylon as a material as you suggested earlier.

INDEED WHY WOULD WE EXPECT THE SAP IN A TREE TO BEHAVE DIFFERENTLY?

Your rope analogy cannot adapt or alter it’s shape, it is after all a solid, so for example as it passes over the pulley it would have to become thinner having shed some rope to the atmosphere and as you rightly state would counterbalance any added density. “your rocks in a bucket”.

When density changes in sap, it exerts a dragging effect on the molecules while at the same time exerts a positive pressure on the molecules in front of it. This positive pressure forces the more dilute xylem sap to move upwards above the original level adding the impetus for the tree to continue to grow vertically. It also explains as I have said before how sap exudes from a cut stem, nothing to do with root pressure but to do again with density changes in the sap!

Here is another analogy. Instead of rope we use stretchy slime. The slime can evaporate water to the atmosphere and become denser. The denser slime bulges as dissolved salts apply positive pressure to the slime causing it to visibly swell, (observed using latex soft walled tubing) and the upward flowing stretchy slime can be drawn up from a reservoir of slime under tension applied by the downward flowing slime causing it to become thinner (again observed in soft walled tubing). But the tree has the equivalent of a fluid filled support stocking “The Bark” that not only prevents the sap from bulging but prevents the internal cells from changing shape-due to the pressures applied internally. Very much like the pressure we apply to varicose veins and oedema using the stockings.

Trees grow and die perpetually or am I mistaken?

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8 years 8 months ago - 8 years 8 months ago #696 by Andrew
Witsend:

Hi Andrew. I'm not in the habit of agreeing with Sophiecentaur - but I must here make an exception. He's drawn an analogy to buckets and stones? Where is your answer? Alternate science is absolutely the very best of all things. In principle I am full blown, heart felt, initiate. But I draw the line when alternate science also becomes illogical.


Page one of this thread contains a reference to our understanding of osmosis by the now late professor H.T.Hammel, Emeritus Professor of the Max Plank Institute and a life,s work into the ascent of sap in tall trees, many published papers and he was definately not convinced by osmosis explaining everything or indeed anything in it's curent format.

Logic must also apply to the curent explanations for the ascent of sap in tall trees, but alas is clearly lacking in logic. For example: the evaporation of water from the leaves cannot suck / drag / move / pull / call it what you like on a column of water in a tall tree! We cannot suck water up more than 10 meters in an open ended tube, many people have tried over the years and failed so why should a tree have different rules?

Ok Andrew K Fletcher - I take it back. That was really well explained. It's more or less what I understood as the action of osmosis. Just couldn't think that it could be improved on or even that it should be questioned.

Clearly there's some nicety that eludes me.

Thanks for the explanation. I now need to understand why Sophiecentaur objects. It's possibly because you aren't qualified? That's why he won't answer my questions. Just tells me to get an eduction. I think we've been joined in the same bracket.

Incidentally I love your quote that you include in every post. I can't get an experiment replicated - and I know a little about that contempt.

Unless it's supposed to be the 'flow' that sustains the flow - being perpetual motion. Sophiecentaur

I think the point is that the sap from the phloem is not the same as the sap from the xylum. The actual sap is different, therefore their molecules are also different.

Here's my take, for what it's worth. The trees' roots are only able to take water in. They do not transpire. So once in it never comes out. That's simple osmosis. I remember it was described as a valve action that closed as the cells became turgid. So it's a one way action. The water is transported from the roots to the the xylum and then up the tree trunk in a sponge action. That precludes a pump action and the question then is how far is the reasonable for water to reach from a sucking rather than a pump action? I know damp rises.

It then reaches the leaves where it is taken into the leaf cells through that same osmotic action. There it is changed into sugar through the miracle of photosynthesis which then is ready to be transferred to various parts of the tree for it's general well-being. Then, having been manufactured the same sugary sap is fed back to the phloem cells in the stem of the leaves - as opposed to the xylum cells at its centre. Excess water is transpired from the leaves as a waste product of photosynthesis, together with oxygen, and the cells, through osmosis take in more water from the xylum cells to replace that lost in transpiration- and on and on. The action is, indeed, perpetual. But only in the same way as our own digestive system is pretty well perpetual. But I'm not sure that it needs anything more complicated than the xylum's ability to hold water - much as a sponge would hold water.

If I've missed the point - apologies.

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Last edit: 8 years 8 months ago by Andrew.

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8 years 8 months ago #697 by Andrew
Lyner:
AKF
You do not seem to understand so much of the Science I quote to you that really cannot rely on your having understood what you have read of H.T.Hammel's work either. Do you have a reference which I can access easily and make my own assessment of what he actually says, please?
If you deny the relevance of Energy in all this, then you are onto a loser if you want a valid theory. Leaves, at the top of a tree, were produced with materials, including water, that had to be carried up there from the ground. If that didn't require energy to raise the stuff in the first place then we have to seriously reconsider the whole of our understanding of everything. Energy is needed to lift the water for transpiration - where does it come from? (Using the accepted definition of energy please)

Your ideas could only be considered if you were to do a complete energy budget, in which you say how much energy is put in, where it comes from and how much is got out.
It needs more than just verbal arm waving. The shape and width of your tubes has no effect on the gravitational potential energy involved in lifting the water. You have, clearly not seen the ultimate relevance of my simplified rope model - the rope cannot evaporate - it is the water in the buckets that evaporates. The rope is the intermolecular attraction, if you like.
As I commented earlier. You just shift your ground rather than dealing with my specific objections. Is that true Science?

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