Where does a tree come from?

I have a little puzzler for you. Think of a 200 year old oak tree, which might weigh over 100 tons. Now thats a serious amount of mass, and we all know that matter cannot be created or destroyed, although matter and energy are interchangeable according to Einstein's equation of E = MCsquared. That mass must have come from somewhere - the question is where. Perhaps you could vote on this, leaving the discussion to a bit later so as to not influence peoples voting. Perhaps you could give me your views by means of the poll.

 

Isnt the answer a mixture? plants are essentially carbon based, and take up CO2, so some of it comes from thin air or rather the co2 within the air. The plants is also heavy with water taken up by roots which absorb the rain and nuturients (which all have mass albeit small) in the ground (from the air again/or ground). The leave photosynthasize(spelling) converting co2 etc into food using sunlight. I know some of this biology is a bit basic, but i think its roughly about right.

 

Gotta admit I found it difficult to pick just one, so I stupidly went for the somewhere else option, which I didn't think was right either.:D

I bet Peter has got some strong scientific therory, if thats the right word, for what goes on.

But we're not supposed to be discussing it NOW.:o

 

Im afraid its all a bit over my head, but voted from the ground. Best part of a bottle of rijoca with my tea hasnt helped me either!

 

I voted for the "somewhere else" option, because really it is a combination of things.

When you consider what makes up the tree, a considerable proportion will be water, which of course it gets from rain. The rest of it of course comes from the ground, and will ultimately be returned to the ground (though not necessarily in the same place). That's why we don't lose or gain any matter, it just shifts about.

 

Thanks for all the votes folks. I won't keep you in suspence for too long - but I am interested in your answers. All will be revealed in a little while.

 

Methinks there is a trick in Peters poll
( the answers not B and Q is it ?)

 

No sun = no tree, no any life as we know it.
Beam me up Scotty:D

As far as I can recollect according to Einstein, matter can be neither created or destroyed -it's here or there in one form or another.

Trees, beans, human beans, all as far as I know rely on solar energy. Click the switch to off and see what happens.

A really interesting thread Peter. I'm looking forward to your definitive answer:thumb:

 

Carbon dioxide water and light I think.:confused::rolleyes:

 

The Air.:thumb:

 

God created everything.

 

Thank you to everyone who participated in this poll, The purpose was to set people thinking, rather than to say that only one of the answers is right. Hence the suggestion of not giving away the answer too soon.

I think this a most interesting question. We see trees and plants every day, but rarely stop and think about where they have come from. The exact answer is a bit more complicated than a single choice answer,and I think some people understood that.

The answer is really quite bizarre - the vast majority of the mass of a tree simply condenses out of thin air. I know that the water is drawn up from the ground, but in principle the tree doesn't come from the ground. After 100 years of growth the ground under a tree is essentially the same as it was before the tree started to grow.

99% of a tree is made up of 4 simple chemical elements. Carbon (the basis of all life forms), hydrogen, oxygen, and nitrogen. And all of those are simply blowing in the wind. The carbon comes from the absorption of carbon dioxide from the air during photosynthesis. The hydrogen and oxygen come from water, which also comes out of the air in the form of moisture vapour that condenses into rain. This falls on the soil and is sucked up by the roots, but it simply passes through the soil and doesn't originate there. Some plants, such as tree ferns, take it directly from the air: they don't need roots for anything other than stability. And nitrogen also comes directly from the air (nitrogen comprises 80% of the air that we breathe). Plants usually can't use nitrogen gas from the air, they want it in the form of nitrate salts. Luckily microbes in the soil are able to absorb nitrogen gas and they convert it into nitrates that the roots pick up. But like the water the nitrogen is simply passing through the ground rather than originating in it.

So does anything come from the soil. They answer is yes, but it is way less than 1%. A simple way to understand what doesn't come from the air is to look at the remains of a tree that has been fully burnt (ie no remaining charcoal). All the carbon, hydrogen, oxygen and nitrogen are returned to the air mainly as carbon dioxide and water vapour. The growing process is completely reversed. Even the heat released is a release of the energy that was absorbed from the sun in the growing process. A bonfire is just a release of stored sunlight. But there are always some ashes left behind. These are the minerals such as potassium, phosphorous, and loads of other trace elements that don't form gasses. These have genuinely been taken from the ground below as they can't be taken from the air. And this illustrates why it is important to return wood ash to the soil. Failure to do so could permanently deplete the ground.

What about the energy from the sun. Well, I am afraid that this was a Herringus rubra. Sunlight is certainly needed for the tree to grow, but energy is very light and the energy stored in the tree will weigh much less than a millionth of a gram. For instance less than 100 grams of material are turned totally into energy in a hydrogen bomb, and a tree holds less energy than that.

So there you are. Quite bizarre. Trees essentially appear out of thin air. Congratulations to all of you who knew that, and to those who weren't so sure - you are in good company. This same question was put to graduate students at MIT (Massachusetts Institute of Technology), some time ago, and 80% of them got it wrong!

 

That's right interesting. It makes perfect sense when you explain it, but as you said, most of us don't really think about it.

 

Um. I ought, as I spent many years telling pupils to do, have read and understood the question.
'Where' not 'how'.
Though maybe a more unambiguous question would have asked - 'from what do trees come from?' But that wouldn't have had quite the same range of possible answers.

Superb explanation Peter.:thumb:
Thanks for posting the thread.

 

Peter - good answer to a good question.( This one is going in the next quiz I set ! ):D
They are growing maize or sweetcorn this year in the fields near my house, and I was wondering where all that growth ( 2 metres in 3 months ) came from. I just could not believe that the soil could supply so much nutrient for this volume of plant material.
To summarise 99% comes through water and the photosynthesis elements. So then all the loving Miracle grow and FBB and chicken poo , et al , that we dote on our little plants - this contributes to only 1% of the grand picture?:confused: