Naked Science Forum

General Science => General Science => Topic started by: gazza711 on 03/07/2015 19:33:38

Title: How does a tree get its mass?
Post by: gazza711 on 03/07/2015 19:33:38
How do trees get their mass?
Title: Re: How does a tree get its mass?
Post by: chiralSPO on 03/07/2015 21:31:10
Most of a tree's mass is derived from water and carbon dioxide. There is also some contribution from minerals.
Title: Re: How does a tree get its mass?
Post by: Colin2B on 03/07/2015 23:18:17
Quote from: chiralSPO on 03/07/2015 21:31:10
Most of a tree's mass is derived from water and carbon dioxide. There is also some contribution from minerals.
Gazza,
The processes in plants take the hydrogen and oxygen in water and the carbon and oxygen in carbon dioxide and rearrange them to make hydrocarbons. In a tree this is mainly cellulose. These hydrocarbons are why plant materials from millions of yrs ago have decayed and formed oil etc, which is what most people think of when they hear the word hydrocarbon.

PS when a tree falls, it is gravity that pulls it down [;)]
Title: Re: How does a tree get its mass?
Post by: chiralSPO on 03/07/2015 23:31:03
Quote from: Colin2B on 03/07/2015 23:18:17

Gazza,
The processes in plants take the hydrogen and oxygen in water and the carbon and oxygen in carbon dioxide and rearrange them to make hydrocarbons. In a tree this is mainly cellulose. These hydrocarbons are why plant materials from millions of yrs ago have decayed and formed oil etc, which is what most people think of when they hear the word hydrocarbon.

PS when a tree falls, it is gravity that pulls it down [;)]

Actually, the tree mostly forms carbohydrates (like cellulose) and lignin, which is almost a hydrocarbon, but still has some oxygen in it. (Technically hydrocarbons only have C and H)
Title: Re: How does a tree get its mass?
Post by: Colin2B on 03/07/2015 23:50:31
Quote from: chiralSPO on 03/07/2015 23:31:03
(Technically hydrocarbons only have C and H)
Thanks, I've been breathing too much oxygen! Must check up on the turpentines and other products, would be interesting to see their chemistry.
Very complex material wood!
Title: Re: How does a tree get its mass?
Post by: PmbPhy on 04/07/2015 08:41:21
Quote from: chiralSPO
Most of a tree's mass is derived from water and carbon dioxide. There is also some contribution from minerals.
An interesting aside on this is that some of carbon in the atmosphere that is absorbed by things like trees is 14C, aka radiocarbon. 14C is produced in the stratosphere by bombardment of cosmic rays on Nitrogen. For details please see: https://en.wikipedia.org/wiki/Carbon-14

As time progresses the 14C isotopes decays into nitrogen. The half-life is 5,730 years. After the tree dies the only change in the amount of 14C in it is the decrease by radioactive decay. By measuring the amount of 14C in the dead tree the age of the material can be determined using carbon dating. See: https://en.wikipedia.org/wiki/Radiocarbon_dating

That's how we can age organic material back as far as 50,000 years.
Title: Re: How does a tree get its mass?
Post by: wolfekeeper on 04/07/2015 23:40:01
Really almost all the mass that makes up a tree comes from the air. The water comes from rain which falls out of the sky, and carbon dioxide comes from the air also.

The sunlight powers the splitting of the water into hydrogen and oxygen and then the hydrogen reacts with the carbon dioxide to form carbohydrates.

The tree also sucks up some nitrogen compounds from the roots to be able to form proteins. These come from nitrogen fixing bacteria, which suck in nitrogen from the air.

The tree also needs trace minerals and various other things from the roots, and it manufacturers oils.