Without Plants, Earth Would Cook

[JimC]

The climax environment for much of Australia is not forest in any case. What was once forest will return to it eventually. The rest will go back to whatever it was, more or less.

Too general for a vastly diverse continent. Many different types of climax community can be found in Oz, including a variety of forests, with the interesting twist that, for at least 50,000 years, aboriginal use of fire for land management has made significant areas of Australia develop a very different vegetation community than what would have otherwise been the case...

[Xamonas Chegwé]

The climax environment for much of Australia is not forest in any case. What was once forest will return to it eventually. The rest will go back to whatever it was, more or less.

Too general for a vastly diverse continent. Many different types of climax community can be found in Oz, including a variety of forests, with the interesting twist that, for at least 50,000 years, aboriginal use of fire for land management has made significant areas of Australia develop a very different vegetation community than what would have otherwise been the case...

Known as a disclimax - or it used to be, the term appears out of favour since I was at college - an alternative climax community caused by human (or other invading species) intervention. The "dis" prefix stands for "displaced" as opposed to being a negation. Examples in the UK are grouse moors, grazed grasslands and, obviously, arable land.

[rainbow]

That's not necessarily so. If the weed load is too high, then you will get a stalled succession, and be stuck in a secondary state for, potentially, good.

The weed load? What exactly is a weed?

When my weed load is too high, I jus' sits and stares into space...

[JimC]

That's not necessarily so. If the weed load is too high, then you will get a stalled succession, and be stuck in a secondary state for, potentially, good.

The weed load? What exactly is a weed?

When my weed load is too high, I jus' sits and stares into space...

That makes me nostalgic...

[pErvinalia]

The climax environment for much of Australia is not forest in any case. What was once forest will return to it eventually. The rest will go back to whatever it was, more or less.

Too general for a vastly diverse continent. Many different types of climax community can be found in Oz, including a variety of forests, with the interesting twist that, for at least 50,000 years, aboriginal use of fire for land management has made significant areas of Australia develop a very different vegetation community than what would have otherwise been the case...

Yeah, this is where is starts getting interesting.

But in regards to the "natural" communities in much of our farming land, it is indeed forest. Whether it can return to that same type of forest is debatable. Thin, nutrient depleted soils, salinity, lack of native species seed stocks and/or faunal dispersal mechanisms, and changed fire regimes, means that there's no certainty in any of this.

[mistermack]

Methane is a short lived greenhouse gas, and in the context that you talk, isn't a threat to global warming. Forests are stores of carbon. If you go from a field of broccoli to a field of wooded forest, you are storing more carbon. That means less carbon in the atmosphere.

Methane is not short lived, when it is continuously produced. It's always there.
And forests take decades to grow. The carbon that they store will be replaced from the oceans, at a similar rate. The atmosphere wouldn't be changed at all by a forest growing. And the carbon stored in the forest is just a one-off. It can never be repeated, without releasing the carbon stored. It's totally insignificant in the long term.

[Xamonas Chegwé]

The climax environment for much of Australia is not forest in any case. What was once forest will return to it eventually. The rest will go back to whatever it was, more or less.

Too general for a vastly diverse continent. Many different types of climax community can be found in Oz, including a variety of forests, with the interesting twist that, for at least 50,000 years, aboriginal use of fire for land management has made significant areas of Australia develop a very different vegetation community than what would have otherwise been the case...

Yeah, this is where is starts getting interesting.

But in regards to the "natural" communities in much of our farming land, it is indeed forest. Whether it can return to that same type of forest is debatable. Thin, nutrient depleted soils, salinity, lack of native species seed stocks and/or faunal dispersal mechanisms, and changed fire regimes, means that there's no certainty in any of this.

Might take a few centuries, even a millennium or two, but it will get there.

[pErvinalia]

Methane is a short lived greenhouse gas, and in the context that you talk, isn't a threat to global warming. Forests are stores of carbon. If you go from a field of broccoli to a field of wooded forest, you are storing more carbon. That means less carbon in the atmosphere.

Methane is not short lived, when it is continuously produced. It's always there.

And it always was when the earth wasn't yet deforested by man. It didn't cause global warming then, because it was part of a balanced cycle. To say that planting forests will add to greenhouse gases is just nonsensical.

And forests take decades to grow. The carbon that they store will be replaced from the oceans, at a similar rate.

I'm not sure what you mean. How will it be replaced from the oceans?

The atmosphere wouldn't be changed at all by a forest growing. And the carbon stored in the forest is just a one-off. It can never be repeated, without releasing the carbon stored. It's totally insignificant in the long term.

One forest, sure. But if the earth was to reforest, it would make a significant difference.

[Xamonas Chegwé]

If mankind were to die out and leave the Earth to its own devices, and if we leave massive amounts of greenhouse gases in the atmosphere that raises the temperature significantly, this will have many effects on the climate: -

A rise in sea-level.
A far more humid atmosphere due to higher temperatures and increased sea area massively increasing the evaporation rate.
Higher temperatures.
Higher CO2 levels.

All of these factors are conducive to plant growth and, with no agriculture to artificially control environments and a raised tree-line due to higher temperatures raising the snow-line, would be the perfect environment for a massive increase in tree growth. Result, all that carbon (or a lot of it) gets locked up over a few millennia, and things slowly return to an equilibrium similar to that before us pesky apes started meddling.

Methan in the atmosphere is naturally converted to CO2 and water in the upper atmosphere. It has a shelf-life of about 10 years. So that would only have a relatively short-term effect on global climate.

[cronus]

If mankind were to die out and leave the Earth to its own devices, and if we leave massive amounts of greenhouse gases in the atmosphere that raises the temperature significantly, this will have many effects on the climate: -

A rise in sea-level.
A far more humid atmosphere due to higher temperatures and increased sea area massively increasing the evaporation rate.
Higher temperatures.
Higher CO2 levels.

All of these factors are conducive to plant growth and, with no agriculture to artificially control environments and a raised tree-line due to higher temperatures raising the snow-line, would be the perfect environment for a massive increase in tree growth. Result, all that carbon (or a lot of it) gets locked up over a few millennia, and things slowly return to an equilibrium similar to that before us pesky apes started meddling.

Methan in the atmosphere is naturally converted to CO2 and water in the upper atmosphere. It has a shelf-life of about 10 years. So that would only have a relatively short-term effect on global climate.

It's like the markets you can buck them for a while but leave them be and they return to their natural random state of unpredictable ups and downs...

[mistermack]

I'm not sure what you mean. How will it be replaced from the oceans?

You need to read up on vapour pressure and partial pressure. But in simple terms, CO2 is constantly passing from air to sea, and from sea to air. For any quantity of CO2 in circulation, the system finds a balance, with the proportions in sea and air settling down to fixed ratios.
If you remove CO2 from the air, you upset that balance. More CO2 is then leaving the ocean, than is entering it. So you get a transfer from water to air, till a new balance is achieved.

In practice this means that if you increase CO2 in the air, over a period, most of it goes into the water till a new balance is reached, and you increase the acidity of the ocean, as I'm sure you will have read.

Exactly the same thing happens in the opposite direction. Reduce the CO2 in the air, and over a number of years, it's replaced from the ocean, and you REDUCE the acidity of the ocean.

So if you plant forests, because they grow so slowly, they are effectively taking CO2 from the oceans. They take it from the air, and it's replaced from the oceans.
So you will be reducing the acidity of the ocean a tiny amount, and the CO2 levels in the air a miniscule amount.

If you burn a forest though, you can raise CO2 levels in the air significantly, temporarily, because it happens quickly. But those levels will drop, over a number of years, as the CO2 transfers into the oceans till a new balanced level is found.