Without Plants, Earth Would Cook

[Xamonas Chegwé]

Faith in nature like faith in the noble savage are quaint but meaningless.

What faith? I studied this shit. I know that plants can survive in environments so extreme that they are practically rooted in bleach!

I am not saying humanity will survive. But life will. It will take more than a loss of modern agriculture to prevent it. If the human race vanished tomorrow, the Earth would sort itself out within a couple of centuries.

[JimC]

In any case, the discussion is almost certainly moot. There is not going to be a mega-collapse which suddenly sees all the productive agricultural land on Earth abandoned, and reverting to its natural state at whatever speed... (and I agree with XC that it would revert, although some areas that have been extensively degraded might take a very long time indeed to reach the equivalent of their previous climax community)

SF dystopias have a peculiar and morbid attraction for some, but are not a good predictor in any rational sense...

[cronus]

In any case, the discussion is almost certainly moot. There is not going to be a mega-collapse which suddenly sees all the productive agricultural land on Earth abandoned, and reverting to its natural state at whatever speed... (and I agree with XC that it would revert, although some areas that have been extensively degraded might take a very long time indeed to reach the equivalent of their previous climax community)

SF dystopias have a peculiar and morbid attraction for some, but are not a good predictor in any rational sense...

We'll see. Doubt a system that is larger than the Earth will produce a good outcome if something did collapse it.

[Svartalf]

Bad things would happen to the planet if modern agriculture stalled for any reason.

No. All those monocultures would very quickly progress through a series of seral communities until they reached the natural climax community for that region. In other words, stop ploughing, seeding, weeding and fertilising and the land will go back to whatever it looked like before you started. In the case of the UK, most agricultural land would progress via grassland and scrubland to deciduous forest - a far better absorber of CO2 than a wheatfield!

Yup. Most of these islands - indeed, most of northern Europe - used to be covered in forest until relatively recently. No global warming then ...

Define "relatively". Most of the primmeval forest in France had been dealt away with before Roman times... it just came back during the Dark Ages before the great clearing works of the high middle ages... maybe the first clearings took place in the neolithic period, long before the Celts arrived.

[Xamonas Chegwé]

Bad things would happen to the planet if modern agriculture stalled for any reason.

No. All those monocultures would very quickly progress through a series of seral communities until they reached the natural climax community for that region. In other words, stop ploughing, seeding, weeding and fertilising and the land will go back to whatever it looked like before you started. In the case of the UK, most agricultural land would progress via grassland and scrubland to deciduous forest - a far better absorber of CO2 than a wheatfield!

Yup. Most of these islands - indeed, most of northern Europe - used to be covered in forest until relatively recently. No global warming then ...

Define "relatively". Most of the primmeval forest in France had been dealt away with before Roman times... it just came back during the Dark Ages before the great clearing works of the high middle ages... maybe the first clearings took place in the neolithic period, long before the Celts arrived.

In ecological terms, before apes found a way out of the trees is "relatively recently".

[Svartalf]

Awright, on THAT scale, it's right.

[Audley Strange]

While large scale organised agriculture might collapse. it would take something even more than an Earth crossing asteroid to turn Earth into a dustbowl. After all it has already happened several times. I was watching something that said that some of those object ignited the air and caused temperature on earth to be over 500 degrees celcius, sometimes for days and that the first things to re-emerge is plants and some grasses do so quite rapidly.

[pErvinalia]

Bad things would happen to the planet if modern agriculture stalled for any reason.

No. All those monocultures would very quickly progress through a series of seral communities until they reached the natural climax community for that region. In other words, stop ploughing, seeding, weeding and fertilising and the land will go back to whatever it looked like before you started. In the case of the UK, most agricultural land would progress via grassland and scrubland to deciduous forest - a far better absorber of CO2 than a wheatfield!

You are dreaming. Most agricultural soil is bleached of natural plant nutrients and without fertilizers would quickly turn to dustbowl red.

Not everywhere, the UK's soil is extremely fertile. It would only be the places where artificial irrigation/fertilisation is needed to grow crops that don't belong in that locale that would struggle. But even they would revert to their natural climax vegetation in due course.

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.

[pErvinalia]

It's simply a fallacy that forests absorb CO2. Yes they absorb it, but they also emit it in virtually equal quantities.
They only absorb it if you plant a new forest where none existed before. As soon as the forest becomes mature, it's pretty much in balance. Otherwise, after millions of years, forests would be thousands of feet deep in carbon-based stuff.

In fact, forests contribute to the greenhouse effect. Because they absorb CO2 and change a significant quantity of it into methane. This is done by soil bacteria, and creatures like termites. And methane is a much stronger greenhouse gas than CO2.

Having said that, forests are a good thing for biodiversity, and they must help a bit in keeping oxygen levels up.

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.

[Xamonas Chegwé]

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?

I'll answer that. A weed is a plant that thrives better in an environment than the things that humans want to grow there! It is a purely anthropic term and has no meaning ecologically.

What causes a disclimax tends to be direct human intervention or the effects thereof (such as grazing). "Weeds" belong where they grow by virtue of the fact that they grow there! The organisms that prevent a climax community developing tend to be animals, not plants.

[pErvinalia]

That's not quite correct. A weed can be exotic, and a weed can have a seed load that is way out of natural proportions with primary species. You are talking about a natural system that hasn't been significantly altered by humans. The fact is, we have changed significantly the proportions and origins of weeds to primary species in our landscapes. And in a lot of cases, native species are either globally extinct, or regionally extinct. There's no doubt that given enough time, plant life will colonise almost any environment buggered up by humans, but to say that it will necessarily return to it's pre-disturbance state is mistaken.

[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?

I'll answer that. A weed is a plant that thrives better in an environment than the things that humans want to grow there! It is a purely anthropic term and has no meaning ecologically.

What causes a disclimax tends to be direct human intervention or the effects thereof (such as grazing). "Weeds" belong where they grow by virtue of the fact that they grow there! The organisms that prevent a climax community developing tend to be animals, not plants.

Agreed that "weed" is an anthropic term, but the existence of an exotic plant without natural enemies or diseases in an area could mean that, if human activity were to cease, the eventual climax community could be very different to the pre-human state. This tends to show up very clearly in places like Oz; England is already such a mongrel plant community with many plants in common with Europe, and many coming from waves of human colonisation, that it is probably in some ways more robust in the face of potential plant invaders...

[Xamonas Chegwé]

That's not quite correct. A weed can be exotic, and a weed can have a seed load that is way out of natural proportions with primary species. You are talking about a natural system that hasn't been significantly altered by humans. The fact is, we have changed significantly the proportions and origins of weeds to primary species in our landscapes. And in a lot of cases, native species are either globally extinct, or regionally extinct. There's no doubt that given enough time, plant life will colonise almost any environment buggered up by humans, but to say that it will necessarily return to it's pre-disturbance state is mistaken.

If you read the thread, Scrumple's contention was that the removal of agriculture would result in dust bowls and barren ground due to all the nutrients being leached from the soil by forced agriculture. It was this bollocks I was arguing against.

Non-native, invasive species would certainly have an effect on the eventual climax community. Plants such as Rhododendron, Himalayan Balsam and Japanese Knotweed would firmly establish themselves in some areas. However, the majority of the UK would return to mature woodland fairly rapidly (within 1000 years) without human interference. The non-native species that would be the greatest factor slowing this return would probably be rabbits - although they would be kept in check by packs of feral dogs, reverting quickly to a wolf-like state, that would become the primary terrestrial predator in a post-human age.

[pErvinalia]

That's not quite correct. A weed can be exotic, and a weed can have a seed load that is way out of natural proportions with primary species. You are talking about a natural system that hasn't been significantly altered by humans. The fact is, we have changed significantly the proportions and origins of weeds to primary species in our landscapes. And in a lot of cases, native species are either globally extinct, or regionally extinct. There's no doubt that given enough time, plant life will colonise almost any environment buggered up by humans, but to say that it will necessarily return to it's pre-disturbance state is mistaken.

If you read the thread, Scrumple's contention was that the removal of agriculture would result in dust bowls and barren ground due to all the nutrients being leached from the soil by forced agriculture. It was this bollocks I was arguing against.

Sure. But even that isn't entirely bollocks. Perhaps in the UK where you have deep fertile soils. But in places like Australia, with thin infertile soils in much of the marginal agricultural lands in the country, the reversion to a woodland of any sort might be a very VERY long time in the coming. In fact, quite large areas of Australia's marginal agricultural lands have become largely useless and certainly can't sustain forest due to the ravages of salinity.

Non-native, invasive species would certainly have an effect on the eventual climax community. Plants such as Rhododendron, Himalayan Balsam and Japanese Knotweed would firmly establish themselves in some areas. However, the majority of the UK would return to mature woodland fairly rapidly (within 1000 years) without human interference. The non-native species that would be the greatest factor slowing this return would probably be rabbits - although they would be kept in check by packs of feral dogs, reverting quickly to a wolf-like state, that would become the primary terrestrial predator in a post-human age.

There's more to the world than the USUK, Seth.

[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.