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Impossible Heights: Newsletter Challenge (August 2012)

Posted July 31, 2012 12:00 AM

This month's Challenge Question: Specs & Techs from GlobalSpec:"

Between 10 and 15 atm of pressure would be required to transport water to the top leaves of California's redwoods, which can reach heights of 120 meters. How could the water be transported upward such a distance?

And the answer is:

When two solutions are separated by a membrane, the solvent in the more dilute solution moves to the more concentrated solution. This process is well known and it is called osmosis. The movement of solvents produce pressure in the more concentrated solution. Eventually the process reaches equilibrium. The pressure at equilibrium (this is the pressure that stops the osmosis) is called osmotic pressure. Now, let's see how water can be transported up the tree. The leaves in trees continuously lose water to the air by a process called transpiration. By losing water the leaf fluid inside becomes more concentrated. Then the water (less concentrated) surrounding the leaves (from the trunk, the branches and the stems of the tree) moves inside by osmosis. Water is pushed up by osmotic pressure. It is not possible to move water up a big distance by a process called capillarity, because capillarity is very low pressure process.

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#1

Re: Impossible Heights: Newsletter Challenge (August 2012)

07/31/2012 12:39 AM

Wicking...

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#87
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/28/2012 3:14 PM

@Solareagle, re wicking

I think you are onto something there. Most of the other replies mention pressure, i.e. pushing up from below or sucking from above. This would have to assume that the tube is airtight, which I very much doubt. There must then also be some serious pressure in the bottom of the trunk - maybe even enough to rupture the tube?

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#92
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/29/2012 8:46 AM

It's not a tube its a cell wall to cell wall transfer water and minerals.

Teak and other trees actually absorb sand and other small mineral particles along with the water passing them up from the roots into the Trunks as the tree grows.

A tree is not static it constantly expands in several directions as it grows a solid mass of cellulose cells.

With many different types of cells doing different tasks roots leaves bark water and nutrient mineral/ transfer.

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#93
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/29/2012 10:28 AM

I believe your first statement is true, which makes your second statement impossible. If there is no tube, then no particles can be transferred. Minerals can and do pass through cell walls, but only in dissolved form, AFAIK.

I have noticed that oak firewood grown in my area (foothills, where much of the water is surface water carrying few minerals) leaves significantly less ash than oak brought up from the valley, where the water has a significantly higher mineral content. I have not had the opportunity to compare redwood from different sources in a similar fashion, but I suspect it would show similar differences.

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#94
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/29/2012 10:45 AM

It is absolutely true that trees are capable of transferring particulates. Speak to a wood trim molder & they will tell you that willow is a hard wood to run for this very reason- the silica particles are murder on the molding knives.

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#97
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/29/2012 11:32 AM

The fact that there are particulates in wood does not indicate that they were transferred from the ground to the wood in the form of particles. The minerals are transported in solution and gradually precipitate to form crystals inside the cells.

At times when water is plentiful, minerals will dissolve and be carried up into the plant along with the water. When the soil moisture drops, plant moisture will drop as well, so the mineral concentration in the cells will rise, and precipitation can occur, forming particles.

Wine commonly forms significant amounts of tartrate crystals (particles) when cooled or aged. This is not an indication of inadequate filtration. All of the ingredients for forming those crystals came up through the stems of the grape vines in liquid form.

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#98
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/29/2012 11:45 AM

You are correct about the precipitation/dissolution equilibrium happening, but i would not apply this to silica (which has an extremely low solubility level!) in the form of sand. This would tend form a somewhat evenly dispersed, very fine precipitate. Willow will have actual, random sand grains.

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#99
In reply to #97

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/29/2012 2:11 PM

I don't think that out-solution depends on a drop the moisture level of the soil. Water incoming from the roots carries minerals, whereas moisture leaving the plant cannot. So the concentration will increase continually until the dissolved material deposits and/or micro-particulates coalesce. I use the term "deposit" rather than "crystallise" because silica For example) typically deposits in glassy form rather than as crystals.

Some trees such as oaks, and scotch pines appear to locate the silica(tes) in micro-tubes, which forms into hard, strong, and abrasive fibres as the sapwood dries out.

Other trees seem to isolate micro-particles into isolated groups, and the particles can be bound by outsolution to form larger particles. I'm not certain whether this is the mechanism for the stones reported in willow.

BTW, both glassy fibres and particles will blunt saws.

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#100
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/30/2012 12:26 AM

take a filtered coffee

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#88
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/28/2012 7:46 PM

It appears everyone is assuming the tree is actually drawing or pushing the water up a continuous tube (the laws of physics make this impossible).

I can imagine two possible answers:

1. the 'cells' of the tree pass water (or water molecules) from one to the other via the cell walls. Kinda loke the check valve theory but bi-directional.

2. Another possibility is is the tree breaking down the length of travel into 'steps'. The water is drawn up into a pool. The next tube is offset from the first and draws again. Maybe this is done somehow on a cell level?

gc

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#90
In reply to #88

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/29/2012 6:31 AM

"up a continuous tube (the laws of physics make this impossible)."

I have no idea what makes you believe this. The pressure on the outside of the roots at the bottom of the tree is sufficient to support a column that is the full height of the tree, so the membranes need to be strong enough to withstand this.

Osmosis can easily generate sufficient pressure.

Similarly, for pure water, surface tension in a capillary of diameter 300nm would generate sufficient tension to draw the water 100-m. Solutes would normally reduce the surface tension, which would require the diameter to be reduced. The only additional requirements are:
that the tree can remove dissolved gases sufficiently that the widest effective tube diameter in the column does not allow the column to break; and
The tubes containing the water don't collapse (and note that for such small tubes the total forces are rather small).

This means that physics per se is not an ultimate limitation. It is all down to the structure of the tree.

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#2

Re: Impossible Heights: Newsletter Challenge (August 2012)

07/31/2012 7:12 AM

capillary action

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Re: Impossible Heights: Newsletter Challenge (August 2012)

07/31/2012 7:17 AM

A combination of processes is involved, including osmosis within the roots, capillary action within the cells in the trunk and branches and transpiration through the leaves (needles). Transpiration (a form of evaporation) creates a 'negative pressure' which provides a sucking action to help draw water upward.

Plus a bit of magic provided by the Keebler Elves.

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#4
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Re: Impossible Heights: Newsletter Challenge (August 2012)

07/31/2012 10:47 PM

GA Usb. So it's a case of the leaves suck and the roots push, with some capillary boost in-between. Energy mainly from the Sun (evaporation)?

-J

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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 9:42 AM

Energy mainly from the Sun

I look forward to the next blog on where energy comes from.

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#74
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/21/2012 6:16 PM

Definitely energy from the sun - but due to photosynthesis producing soluble starches causing osmosis. After all, the main effect of evaporation is that it creates a requirement for the water to be repaced...

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#7
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Re: Impossible Heights: Newsletter Challenge (August 2012)

07/31/2012 11:41 PM

Not to be nitpicky, but the process is primarily osmosis. The transpiration from the leaves results in a partial pressure due to a difference in the purity of the water. The cell membranes want to equalize the partial pressure of the water. Capillary action has very little to do with the process (and generally won't lift water very far...)

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#17
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 5:24 AM

C Warner's comment is correct.

The tracheids in conifers are about 30-um in diameter, which would correspond to a column height of only about 0.5-m for pure water - and starch content tends to reduce the surface tension.

More detail:
The principle mechanism is that starches are generated by photosynthesis in the leaves (needles), and the high starch concentration sucks the water upwards by osmosis. Conversely the starches are pulled downwards by the concentration gradient, so they can be utilised by the remainder of the tree.

With the exception of active pumping and valves, all the other mechanisms so far mentioned in this thread are also known to occur. It has been speculated that there may also be a measure of pumping withing the living parts of the root system only, but it is certainly not a major contributor, and SFIK this has yet to be observed.

References:
http://en.wikipedia.org/wiki/Capillary_action
Ham Keillor-Faulkner in
www.scientificamerican.com/article.cfm?id=how-do-large-trees-such-a&page=2

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#36
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 2:54 PM
Re: Impossible Heights: Newsletter Challenge (August 2012) 08/01/2012 4:24 AM
C Warner's comment is correct.

"The tracheids in conifers are about 30-um in diameter, which would correspond to a column height of only about 0.5-m for pure water - and starch content tends to reduce the surface tension." - Anonymous poster.

When pumping a deep mine it is often necessary to stage the pumping. The lowest pump lifts to a pool that serves as a source for the next stage.

The tracheids are arranged in a fashion that would support this transport mechanism relying on osmosis alone.

However, the same mechanism of lower "valve", tube and upper "valve", will function well if the driving mechanism is mechanical pumping caused by the trunk of the tree swaying in the wind, or the water in the bark being warmed during the day and cooled at night.

There may not be any "proof" as yet that trees use thermal and mechanical pumping, but since they can, proof that they don't is needed before these potential mechanisms can be ruled out.

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#59
In reply to #36

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/07/2012 10:32 AM

All these are valid considerations, but I suggest looking at the accuracy of the question to start; is there any concurrent downward flow of waste elimination products as well or are they strictly disposed of by evaporation (and as oxygen of course & very thankfully!)? This would create a partialsuction effect that could possibly be applied in a staged effect similar to later posts on cappilaries, reducing the overall head pressure effect. Either way, there is definitely not 10- 15 atm. pressure on the sap at the base of one of these!

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#60
In reply to #59

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/07/2012 11:18 AM

Suction of 10-15 atmospheres would seem to be even less likely than pressure of that magnitude. As injured trees seem to seep gently regardless of the location of the injury, the reality must be that there is a moderate net pressure relative to atmospheric at all heights. Can this be achieved by a combination of variable impurity concentration and liquid flow?

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#61
In reply to #60

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/07/2012 11:42 AM

Is there a way to obtain 'suction'>1atm?

Clearly any 'suction'/'negative pressure' is a small fraction of the force required.

Apparently, the answer to your last question is 'yes'.

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#63
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/07/2012 12:13 PM

"Is there a way to obtain 'suction'>1atm?"
Not, so far as I know, that is relevant to this situation (but I didn't wish to dilute my main point).
However, as an example of where such suction is possible, have you ever tried to pull (not slide) apart two wetted surfaces that are closely spaced and held together via a layer of water (the secret is in the radius of curvature of any water surface that could be formed - 1-atm corresponds to approximately 0.75-um ).

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#62
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/07/2012 11:49 AM

there is a moderate net pressure relative to atmospheric at all heights.

That has an insightful ring to it.

What mechanism causes this evenly distributed prorated pressure?

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Re: Impossible Heights: Newsletter Challenge (August 2012)

07/31/2012 10:50 PM

Those who studied Botany should shed some light on this.

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Re: Impossible Heights: Newsletter Challenge (August 2012)

07/31/2012 11:33 PM

Why can not we use pump, if required some more booster pumps in serial...?

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#8

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 12:07 AM

Hi all!

I'm a newcomer and i'm very interested in this subject. So, if i say somethings incorect, sorry every body!

120 meters is approximted to 120 meters of water, so if converts to pressure unit, it's 120m H20 = 12 bar or 11.61 atm. When u transported it to the top, there's a number of loss power. There're two differ loss type, and with the long distance, i think most of loss power is made by the long pipe dimension:

hw = a x v x v/(2.g) x l :

.hw: loss power ( m H20 )

. a: the Coefficient of long loss power, choose = 0,1.

. v: velocity of flow through the area of pipe, choose = 4 m/s

. g: Coefficient of weigh ( m/s/s)

. l: distance transportion ( m )

So, the simple loss power maybe calculate by:

hw = 0.1x4x4/2/9.81 x120 = 9.785 mH20

Choose hw = 12m, so required pressure is: 12+120 = 132 mH20 = 12.77 atm

So, if we chose pressure is 13 atm, it can transport water up to the top ( about energy ).

But this fomular is so simple, every coefficients must choose base on the conditions of transportation, the dimension we design, the specification table, ...

Thanks for reading!

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#9
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 1:03 AM

All living things are made up of cells sell contains cell sap and the cell membrane is permeable as such water can pass through the cell membrane through osmosis. Due to evaporation of water from the leaves the cell sap in cells at top level become much concentrated than draw water from adjacent cell below by osmosis effective increase in cell sap concentration of cell below it and the process repeats thus from rout to top the water moves from cell to cell by osmosis

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#75
In reply to #9

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/21/2012 10:00 PM

This is the closest to the correct answer one cell wall to another overcoming 2,000 psi at the base if it was a pipe this is more of a wicking action than a pumping action.

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#13
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 1:21 AM

Do you not have trees where you are?

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#10

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 1:03 AM

None of the above.

The giant redwoods grow that tall only at selected areas of the west coast, where upwelling of moist air from the ocean deliver a fog regularly to the top of these trees. It is soaked up where is needed and used.

Excess moisture is used at night, when the leaf's pores are open, and can be delivered to the roots via capillaries. Friction is sufficient to drop the pressures to manageable levels. Communication from the roots upwards is possible via checkvalves, the same system your veins in the legs are using, or the long neck of a giraffe. But, from the top of my head I do not know, if that actually takes place or not in the redwoods..

What I know is, that Nature reuses anything invented once.

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#16
In reply to #10

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 5:02 AM

Fog is responsible for at most 40% of water uptake.
In any case, without valves or osmosis the water would simply flow down to the base of the tree.
Redwoods do not have a system of valves. They rely almost entirely on osmosis.

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#41
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/02/2012 12:46 AM

isn't osmosis a kind of valve?

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#45
In reply to #41

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/02/2012 3:51 PM

No - try Wikipedia?

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#24
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 9:39 AM

Very good points made.

The question 'googles' too easy. If proffered answers were correct, we'd have tall trees everywhere. A look on the interweb for an answer, and it's much said (Saw this one the other day and couldn't be ******* to state interweb wisdom). Question remains, why in that location ?

I'll not list the webplaces I've looked at, the audience is aware enough to do that themsef, and answers given. If this were a simple problem, Redwoods would be growing all over the place.

GA for stirring the pot. This question might have been better posed as, "why do redwood grow in California?'

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#30
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 11:15 AM

The fog is required when the ground is dry, which in California is during the growing season...

You can say that mist, fire, silica and tannin are absolutely relevant to the life cycle (and eventual height) of giant redwoods, but maybe those are answers to different questions.

There are giant redwoods thriving in Kew, without the benefit of coastal mist. They are only 150 years old, so of course nowhere near 115-m tall. It could be interesting to return in 1000+ years to see whether they have reached their full height.

If you are after alternative questions, you might consider: "Why does the continuous path of water (needed to transport minerals from the soil) not cause water to drain away from the top of the tree?"

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#34
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 1:43 PM

You have a valid point. There are quite a few planted coast redwoods (Sequoia Sempervirens) of similar age here in the foothills and also in the central valley, where there is essentially zero summer fog. In these locations, they must have continuous artificial or natural ground water. I have seen at least a couple of places where properties were abandoned; once the artificial water source is cut off, the trees die.

The giant redwoods (Sequoia Gigantea) do not naturally grow along the coast. Rather they grow at significantly higher altitudes where orographic lifting provides them with some summer fog and adequate rainfall. The northernmost grove is at an altitude of roughly 5000 ft (1500 m) about 25 mi (40 km) NNE from here. The larger southern groves are at higher altitudes; in Sequoia National Park, most of them grow at around 6000-7000 ft. (1800-2100 m) altitude.

The giant redwoods are generally not as tall as the coast redwoods, but they are much larger in girth. Check out the Mark Twain Stump, which is about 25 ft (nearly 8m) in diameter.

I suspect that the trees in Kew Gardens are coast redwoods (flat, soft needles/leaves), rather than giant redwoods (rounded conical pointed scales/leaves).

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#44
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/02/2012 3:04 PM

Some of each

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#39
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 7:45 PM

Fog doesn't carry nutrients.

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#11

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 1:05 AM

capillarity - like liquid helium

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#38
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 5:19 PM

Capillarity: making fun of hats

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#12

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 1:19 AM

Trees just suck.

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#14

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 1:48 AM

the water isnt really being transported 120 metres , it is being transported 0.1 mm or so each time , 1,200,000 times over , moving from cell to cell by osmosis carrying nutrients with it from the soil

question i have though, is what mechanism controls the amount of water shared with cells lower down the tree and those at the top , where is the "brain" that decides how much sugars , nutrients and other chemicals are blended and carried to which parts of the tree , and if there is a process of cell building to create wood , then is there also a process to remove waste products ?

if trees dont have a " brain " then what consciousness controls its growth to become what it is ?

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#42
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/02/2012 12:50 AM

FIFO - first in first out

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#46
In reply to #14

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/02/2012 4:20 PM

Not a brain, but lots of local equilibria driven by individual cells adapting to local conditions.

I.e. cell activity regulates local equilibria between water uptake/evaporation (leaves) water uptake (roots), creation of starches by photosynthesis (leaves), and extraction of starches (all living cells). There is also some completely passive activity "dead" cells).

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#15

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 4:17 AM

It's a combination of suction, (like putting blotting paper in water, if you leave it long enough it will travel to the top) and dew which although it doesn't look much but deposits masses of water, if you look at a high hill or mountain, without any rain there are always rivulets running, the more mist the faster the rivulets run,the same with fog, ( If I stole a bucket of fog, would it be mist?).

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#27
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Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 10:24 AM

"If I stole a bucket of fog, would it be mist?"

If it came from California, its to Oregon.

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#31
In reply to #27

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 12:02 PM

Thats not fair you get 5 I get Zippo.

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#35
In reply to #31

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 2:21 PM

Now you got the 5!

They should really make the off-topic points be negative; it takes 5 GAs to offset a single initial OT, or 7 GAs to convert a single OT into a GA. I have no idea how they chose the value of 5...

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#49
In reply to #35

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/03/2012 9:36 AM

The 5 only applies if the OT is applied by the auteur. As this means it is deliberately off-topic, it would seem reasonable never to allow it to become a GA.
On the other hand... that usually has five fingers as well

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#50
In reply to #49

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/03/2012 11:28 AM

I have to disagree. I have seen several cases where the original author marked the post as Off Topic, but I considered it not only On Topic, but a GA as well!

If I were in charge, I'd make an author-marked OT worth -2 points (or 2 OT points). It would still take 4 GA votes to make it become a GA.

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#51
In reply to #50

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/03/2012 4:21 PM

The whimsy (five fingers on the other hand) implied that the choice was made arbitrarily - do you disagree?

It seems to me that this also applies to the community's awarding of GAs. Even the presently voted "GA" (one of the more justified in recent challenges) could be regarded as dubious, given that

Osmosis is relegated to the roots,

Capillary action (which is featured equally with osmosis) provides less than 0.5% of the "lift", and

"Negative pressure" is meaningless here, as the needles would wilt in the absence of positive internal pressure.

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#53
In reply to #51

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/03/2012 9:38 PM

I've never heard of a connection between the word 'whimsy' and 'five fingers on the other hand'. I checked four different dictionaries, and none even hinted at such... So I fail to see the connection to the number 5.

It is certainly true that the decision of whether a post is on- or off-topic is often more than a little arbitrary. This is the case both for the original author and for anyone reading a given post.

"Osmosis: a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one, thus equalizing the concentrations on each side of the membrane." Why should that be limited to the roots? When you cut a wilted branch and place it in water, I believe it is mostly osmosis that makes the leaves lift up again.

I do agree that capillarity is a small part of the force involved, although I have no way to assign a value to that fraction.

I'd agree with you on the wilting from 'negative pressure' for most trees, but redwoods (both coast and giant) have much more structure in their leaves than most other trees. I have both growing here, and neither wilt perceptibly, even when a branchlet dies.

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#55
In reply to #53

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/04/2012 5:14 AM

English is a difficult language...

On the other hand... 5 fingers per hand... So let's make the number 5...
These "connections" were whimsical suggestion on my part as to how CR4 might have arrived at the number 5 (I can't imagine the actual basis to have been any less arbitrary - though it may have been less irrational).

The statements from Usbport's "GA" that I highlighted were those that I believed to be unhelpful.

Specifically, "relegated" is always a human assignment, not a physical fact; in this case it refers to Usbport's assignment of all osmotic activity to the roots. Osmotic processes determine the counterflow of water and starches throughout the interior of the tree; however, I suspect that Usbport intended a reference to osmotically active membranes, which are indeed confined to the roots and (theoretically) to the leaves.

Capillary proportion: I checked the references and used the 0.5-metre maximum value for the capillary effect proposed by Anon1.

Wilting: "perceptibly" is the operative word here. Rigidised dead structure will hide the appearance of wilting, but I believe that the living cells will still shut down in much the same way in a needle as they do in a more conventional leaf. However, a better demonstrator for the absence (both of leaf suction and of capillary pulling) is that the trunks always "bleed" when injured, regardless of height.

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#56
In reply to #55

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/04/2012 10:36 AM

Ever heard of xylem and phloem?

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#57
In reply to #56

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/05/2012 1:41 PM

Yes, thanks. Mature phloem in conifers does not appear to be adapted for long-range moisture transport. So the 30-um diameter I used for calculating capillary lift relates to secondary xylem.

Unfortunately (from the aspect of absolute precision), my comment relating to high trees negated effects that are negligible in this regard. Yes, there can be some small negative pressure - but it is limited by transpiration energy as well as by what can be supported by surface tension and by the structure of the leaf.

Maybe I'm mistaken, but I didn't think expression of this nomenclature would add significantly to the discussion.

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#82
In reply to #51

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/28/2012 10:09 AM

"Negative pressure" is meaningless here, as the needles would wilt in the absence of positive internal pressure.

Not necessarily. That might be why they are needles instead of leaves.

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#78
In reply to #15

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/23/2012 1:32 AM

Blotting paper cellulose redwood cellulose wicking action not sucking.

Mist Clouds Fog thats evaporation and condensation tree is just in the way.

Read question again.

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#18

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 6:05 AM

Root cells actively import mineral ions. This effectively reduces water concentration inside the root cells, and water moves in by osmosis generating pressure upwards from the roots. Water inside the tiny tubes (in the xylem) adheres to the walls of the tube by hydrogen bonding, supporting the column of water against the force of gravity. Water is cohesive due to hydrogen bonding and the column of water is able to act as one mass from roots to leaves. Water evaporating from the leaves creates a low water pressure within the leaf which creates a pulling effect, raising the column of water up through the plant. So, root pressure, cohesion-tension, and evaporation from the leaf power the 'transpiration stream'

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#19
In reply to #18

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 6:43 AM

Although minerals contribute to the osmosis, the effect is relatively small. The reason is that sap has much higher concentrations of starches than of mineral ions (maple syrrup, anyone?).

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#20

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 8:12 AM

how about tree gnomes with really small buckets and lots of rope?

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#21
In reply to #20

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 8:57 AM

....they'll just have to have a toke more frequently...

Hang on,, that says "rope". Disregard.

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#22

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 9:17 AM

The water gains potential energy on its way from the ground to the leaves.

The energy must be coming from the transport mechanism. I can't model how or where that energy transfer occurs. Bio pumping and valving perhaps? Any one care to have a stab at that?

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#23

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 9:18 AM

How could the water be transported upward such a distance?
Rainfall.

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#26
In reply to #23

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 10:07 AM

Like heat travel from hot to cold area,moisture too travel from moist(earth) to dry area(top of trees).

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#33
In reply to #26

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 12:53 PM

All i am stating is why make something more complicated than it has to be. I am a believer in the KISS principal.

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#28
In reply to #23

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 10:39 AM

Evaporation goes up. Rainfall comes down.

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#29

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 10:49 AM

The transfer of force horizontally in this Newton pendulum is pretty understandable. Similar shift of material (water) could happen in plants as well. I don't think the static pressure of bottom cells of a coconut tree would be greater than those of a banana tree. Like each person passing a brick to another person who is above him, until each brick reaches up to 3rd floor or 3oth floor or even 300th floor, if those many people are there.

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#32

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 12:24 PM

My little experience is that most of the water is transported upwards between the trunk and the bark. Could it not be because of stretching and shrinking of the bark due to heat changes or flexing of the tree by wind.

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#37

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 4:50 PM

The General Sherman Tree has 600,000 board feet and the trunk itself weighs over 4,000,000 pounds and is estimated at 2000 yrs old.. . About half the weight is water which it can drink around 500 gallons of a day....


http://www.youtube.com/watch?v=QJvtJeB2Iq0

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#40

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/01/2012 8:33 PM

In the Journel Physics Today Feb 2000 was an article that breifly mentioned about this remarkable fact that trees can move massive amounts of water through huge verical distances.

Trying to explain this phenomina via fundamental physics is not easy and certainly many people who have tried to answer this question are pretty close. My contribution would add that water itself has a remarkable property it actually be subjected to huge NEGATIVE pressures. This might sound wierd but it is possible to have a huge column of water in a perfectly sealed tube with an open bottom and not pour out. This is very difficult to achieve in practise. Marcellin Berthelot in 1850 claimed a negative pressue of -50 atm in a glass ampoule. Recently experiments done with natural rocks in 1991 has a figure of 1400 atm.

So water in a sense can be very difficult to "pull apart", like it is very difficult to compress. In a tree is a massive network of fine capillaires that spread out in the crown of the tree into a massive surface area so the adhesive forces would be massive and then with the energy of the sun evaporation of the water molecules would allow massive amounts of water to "pulled up" into the atmosphere.

A truely remarkable process. Well thats my contribution,

Cheers Alan Mainwaring

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#81
In reply to #40

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/28/2012 9:54 AM

Sometimes called the tensile strength of a liquid.

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#43

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/02/2012 12:59 AM

has there ever been a detection of motion in the diameter of a tree?

this would be a sign of pumping inside the tree.

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#47
In reply to #43

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/02/2012 4:28 PM

There are small changes in the diameter - due to varying osmotic pressure. But this has nothing to do with mechanical pumping. Indeed, it's proven (as far as anything can be in botany) that no mechanical pumping mechanism exists in the phloem.

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#48

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/02/2012 4:55 PM

The mechanism that enables redwoods to raise water to great heights (and/or to retain it there) is osmosis.

The reason that redwoods can grow during summers with low rainfall is that the leaves can absorb moisture from rising mists; this also causes temporary flow of fluid down the tree, which assists in transport of photosynthesized material to bulk the trunk.

The reason redwoods can grow so tall and fat is that the high tannin in the trunk content protects it against pests - so they stand for long enough to do so.

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#52

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/03/2012 8:04 PM
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#54
In reply to #52

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/04/2012 4:42 AM

That water is never going to drip out at the top of those tubes.

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#58

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/07/2012 10:03 AM

Use a coffeemaker!...Of course, a really big one. Heated by the Calefornian sun.

Side effect: The water becomes sterilized.

Maybe that more than one machine is necassery. I don´t know because I don´t build such machines but I use them to produce "American coffee, European style".

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#64

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/07/2012 1:52 PM

It has been evoked already that the water and nutrients do not need to go up a 120m column. There is no straight tube (like veins) going up the length of the tree.

Osmosis and capillarity will do the trick and work on much shorter distances.

The question is - deliberately I assume - misleading. You don't need 15 atm of pressure.

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#65
In reply to #64

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/07/2012 3:51 PM

I think Kris already pointed out (post 54) that the benefit of capillary lift could only be taken a single time. So it's down to osmosis (also a one-time effect - but capable of generating extraordinarily high pressure differential) to provide the lifting and variable concentration and flow to balance the pressure locally.

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#67
In reply to #65

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/14/2012 2:30 PM

Osmosis is a one-time effect? Yes, it would be if it were not for the fact that active pumping of ions across a membrane or other active transport can "restart" the osmotic process by regenerating relatively pure water. Not that that mechanism is being used here, but it is possible.

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#68
In reply to #65

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/14/2012 3:00 PM

Osmosis is a one-time effect per cell! If concentrations of whatever impurity (starches, minerals, salts, ...) vary from cell to cell, then osmosis can repeat (with reduced ∆P[Does ∆ appear as Delta on all machines?]) from cell to cell. The ∆P from one cell to its neighbor only needs to lift the water the height of one cell. The cumulative effect is obviously considerable!

I haven't seen any other adequate explanation...

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#71
In reply to #68

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/14/2012 5:26 PM

I think you are saying that the pressure lift depends on the concentration differential across a membrane, and the concentration can drop above that without a change in pressure.

This is in principle this could be partially true, albeit the concentration gradient will drive counterflow of fluid and impurities to balance the concentration, so the repeat will not in practice allow water to be pumped continuously through multiple stages. (Semiconductor engineers will be familiar with these issues).

Even insofar as the mechanism exists, there are two major difficulties with this proposal when applied to trees.
The first is the absence of any mechanism that will drive impurity concentration at the base of the tree to a level that exceeds the concentration where the impurities are generated.
The second is the absence of secondary membranes to drive the repeat mechanism.

The reality is that a single stage of omsosis can generate extremely high pressure, certainly tens if not hundreds of atmospheres; any limit lies in the strength and underpinning of the membrane.
NB that the weight of the tree has to be supported by pressure on its base, so this is not introducing a new problem in terms of the strength of the root structure.

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#103
In reply to #68

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/30/2012 5:14 AM

My previous comment was incomplete and probably misleading:
although osmosis is not a per-cell effect, the net pressure the tree could be maintained near-neutral at all heights if there were frequent membranes and the impurity concentration rose from section to section as we went upwards. This could possibly be effected via a simple feed-back mechanism in the photosynthesis - excess pressure slowing the production of sugars. On the face of it, however, it would either require the sections to be multi-cellular so that each communicated with needles at similar height, or for there to be an active mechanism for transferring the starches across cell boundaries. IMH(and ill-informed)O, the active mechanism looks to be more likely.

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#66

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/08/2012 1:05 AM

ever pumped up a tree with 15bar/240psi?

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#69

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/14/2012 3:11 PM

I wonder if water is conducted upward from the roots of Sequoia Sempervirens to the top of the tree. Since these coastal redwoods are usually located at the bottoms of valleys close to the coast where there is a lot of fog, wouldn't the fog coalesce on the leaves/needles to allow foliar watering?

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#70
In reply to #69

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/14/2012 3:31 PM

See posts #30 and 34.

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#72

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/17/2012 7:57 PM

As far that I heard this trees have a special.... let say weather canopee system , it seams they get the water not from the ground but from the top of the tree

it seams ??? that it is what these trees can survive only in some special misted environement ??

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#73

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/21/2012 4:19 PM

It is the result of capillary action and water surface tension that causes the water to climb in micrometer increments from cell to cell rather than the equivalent pressure of tree heigth measured with water columns etc.

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#76

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/22/2012 1:36 AM

Have an uneasy feeling of inventing a "perpetuum Mobile"!!!!

Do your all answers trying to explain it ?!?!?!?

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#77
In reply to #76

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/23/2012 12:44 AM

a "perpetuum mobiole" is a machine producing even much energie as it uses to run

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#79
In reply to #77

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/26/2012 2:05 AM

Perpetuum Mobile - taken from Latin; perpetual movement !! - no need to add energy

creating the movement (self sufficient !!)

Because this idea failed acc. Energy laws - all explanations stated for water lifting without anergy added -is irrelevant!!

See all the capillarity etc explanation-are incorrect !! As they will "contribute"

to repeating the invention of "Perpetuum Mobile"...

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#80
In reply to #79

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/26/2012 5:37 AM

One-time energy can come from anywhere (surface states, cooling...) You mean power, I think.
Evaporation uses power from sun.
So this is not the reason why capillary + evaporation is incorrect (though I still believe it to be an entirely inadequate explanation)

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#83
In reply to #79

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/28/2012 10:22 AM

I agree. osmosis and cappiliary action are mechanisms. So far no one has explained how the water's potential energy is raised to get it from the ground to the leaves.

Heat of evaporation changes the state of the water from liquid to vapour but doesn't provide the power to lift the water.

I don't think the action is unique to just Redwoods. I think every tree would work the same way. Redwood is just an extreme machine.

Wicking? Hmmm. I can't get my noggin around the energy budget in that.

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#84

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/28/2012 10:32 AM

"Between 10 and 15 atm of pressure would be required to transport water to the top leaves of California's redwoods, which can reach heights of 120 meters. How could the water be transported upward such a distance?

The answer to this challenge will be posted later this month, right here on CR4."

It's getting pretty late in the month, so where is the 'official' answer?

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#85

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/28/2012 11:41 AM

If we were dealing with a simple column of water in a single tube, then the assumption might be valid. But we have two types of tissues in plant stems, xylem and pfloem, each composed of cells in a rigid matrix functioning like the bricks and mortar in a wall. One of the tissues conducts water and inorganic nutrients from the roots to the canopy, the other conducts water and organic nutrients from the canopy to the roots, and the rigid cell walls carry the weight as mortar in the wall. Each cell is responsible for its own local transfer. (Biology 1402, Pan American University, Edinburg, Texas, Spring Semester, 1966, Dr. L. O. Sorensen)

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#86
In reply to #85

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/28/2012 12:30 PM

This isn't too easy for outsiders to find. Also, it's possible that some of the detail proposed as universal in 1966 applies to hardwoods but not to the "more primitive" softwoods.

The article in Physics Today, Jan 2008 is less complete, but illuminating, though it's still not clear whether the proposed mechanisms fully apply to softwoods.

Unfortunately, there is a lot of authoritative-looking stuff out there that is misleading including statements such as "root pressure is absent from ... tall trees or long vines"

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#89
In reply to #86

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/29/2012 5:54 AM

You still cannot adapt the "Perpetuum Mobile" system in any physics Article !!

Or is it ?!?!?!?!

Where exactly the Energy added-lifts the water up ?!?!?

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#91
In reply to #89

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/29/2012 6:54 AM

No perpetuum mobile is required.

The source of energy/power is the heat/light of the sun. The intermediary is evaporation of water. The only possible issue is understanding how the lifting mechanism affects the energy required to evaporate the water.

For surface tension, suppose evaporation removes water from various levels of the tree. Surface tension will replace it. Note that more energy is required to evaporate water from a convex meniscus than from a flat one; this equates to the extra energy required to draw the water up the tree (even assuming a fixed tube diameter, the meniscus would become more concave as we ascend the tree).

For osmosis, evaporation again removes water from various levels of the tree. The increased concentration causes water to flow from the dilute side of any membrane to the concentrated side. Here the energy equation is slightly more complex:
the vapour pressure of water reduces with increasing impurity concentration, so more energy is needed to remove a given mass of water;
in (small) addition, osmosis tends to cool the dilute side and heat the concentrated side - so some heat is extracted from the ground.

BTW, so far as I can see either or both of these mechanisms must be involved. However, even after reading a few papers, I don't know enough about the structure of conifers to be able to answer to the original question

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Guru
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#95

Re: Impossible Heights: Newsletter Challenge (August 2012)

08/29/2012 11:10 AM

AND THE ANSWER IS: WRONG!

Referring to "And the answer is: When a sound signal is received by a linear system (linear response) only the fundamental tones (the ones actually present in the sound) is sensed or transmitted. However, if the system exhibits non-linear responses, not only the fundamental tones are sensed and transmitted, but also the system reproduces the harmonics of each one of the tones present in the sound. This means that the non-linear system reproduces the sums and differences of the whole number multiples of the fundamental frequencies. It happens that the system formed by the ear and brain is actually a non-linear system, so we hear a low fundamental tone (like in human speech) and all the harmonics produced by the system, including the large wavelength of the bass tones."

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