Terraformed Ecosystem Peculiarities

[Flyndaran]

Originally Posted by Agemegos

Not only is pedogenesis a key goal of terraforming in itself, but also more carbon is stored in soil than in [living] plants.

I imagine most terraforming would be the thousands+ years of boring genetically engineered smut covering the planet converting all that CO2 into coal-dust "snow" and spitting out O2.
Though oxidizing all that iron would free up a lot of sulfur turning the oceans quite acidic making the planet far more hostile to earth life before getting less.

[acrosome]

Originally Posted by Johnny1A.2

But does that necessarily mean that there would be no calcium carbonate type minerals at all?

There are also the profoundly weird carbonatite volcanoes.

Originally Posted by Johnny1A.2

Here's a thought: a terraformed world might be very short of good-quality iron deposits, though. It's widely thought that Earth's iron ore is largely of biotic origin.

Absent life, what might precipitate iron out of the oceans into useful form (assuming there were oceans). Absent oceans, what abiotic processes might produce useful iron ore?

That would depend upon the geology of the world, I suppose. There are volcanic deposits of just about any metal you can think of, copper especially but iron too. And gold. As I said- just about anything. And the Venera missions discovered, for instance, that Venus apparently has chondrules of both iron and metallic aluminum in at least some of its regolith. (The aluminum is often mixed with calcium or titanium.) Thus my earlier questions about low-TL smelting of aluminum. I have since learned that it is ridiculously easy. There is even a series of books about bootstrapping yourself a machine shop and it starts with smelting aluminum in home-made crucibles. (I have a copy- fun reading, and absolutely vital for any post-apocalyptic settings.)

I've been reading up on Venus recently.

[lwcamp]

Originally Posted by Agemegos

Remember that unless you're planning to exterminate an existing biosphere you not only have to oxidise the atmosphere but create the soil. There are millennia of work to do before you introduce large land animals

On earth, it took about a billion years to fully oxidize the ferrous iron dissolved in the oceans to the point that oxygen could start accumulating in the atmosphere in significant concentrations. Cutting it down to mere millenia using only biological means sounds rather optimistic.

Luke

[lwcamp]

Originally Posted by Anthony

You pretty much want wild uncontrolled excess in the prey. Actually, for a long time you probably only want plants, feeders are what you introduce when you want to stop the process.

If only herbivores are present, in several of their generations (maybe a decade or two for something like white-tail deer, much less time for smaller critters like rabbits) they will have over-grazed/browsed the rangeland to the point that they will significantly impact the productivity of the land and will be suffering from serious malnutrition. Introducing predators can increase the overall health of the hers and restore productivity to the land.

Luke

[lwcamp]

Originally Posted by Johnny1A.2

Here's a thought: a terraformed world might be very short of good-quality iron deposits, though. It's widely thought that Earth's iron ore is largely of biotic origin.

If you have oceans and a reducing atmosphre, you will have a lot of ferrous iron dissolved in the oceans. If you then make the atmosphere oxygen-rich enoughto breathe, you need to turn the iron into insoluable ferric iron. This will lead to extensive iron deposits on the ocean floor. Since these will be of relatively recent origin, the iron can be dredged or suctioned up.

Originally Posted by Johnny1A.2

Absent life, what might precipitate iron out of the oceans into useful form (assuming there were oceans).

A warmer world than Earth could lead to turbulent convection of the atmosphere above the level at which ozone is formed, or a runaway water-greenhouse condition where water vapor rises above the ozone layer. This would lead to the hydrolysis of water and subsequent escape of the hydrogen, leaving behind an oxygen-rich atmosphere. If this process goes to completion, expect an atmosphere of mostly oxygen with a density greater than the atmosphere of Venus (along with the dissappearance of the oceans). Shutting down tectonic recycling of the crust could have similar effects by cutting off the surface ocean from the water in the upper mantle and preventing removal of atmospheric oxygen by weathering. A higher UV output from the parent star might also have this effect (or it might just make a thicker ozone layer).

Luke

[Anthony]

Originally Posted by lwcamp

If only herbivores are present

Why are you introducing herbivores? Really, if it doesn't contribute to binding carbon, all it's doing is slowing down the process.

[Agemegos]

Originally Posted by Anthony

Why are you introducing herbivores?

To form soil, to transport carbon from the biotic reservoir to the soil reservoir, and to prevent the accumulation of fuel loads dense enough to support wildfires that will be hot enough to kills seeds and fire-resistant plants.

Also, to disperse seeds and spores.

[Anthony]

Originally Posted by Agemegos

To form soil, to transport carbon from the biotic reservoir to the soil reservoir, and to prevent the accumulation of fuel loads dense enough to support wildfires that will be hot enough to kills seeds and fire-resistant plants.

I'm not inclined to classify aerobic and anaerobic soil bacteria as 'herbivores', and they certainly aren't controlled by predators. Fuel loads aren't really an issue until the O2 concentration gets pretty high, and can be controlled by choice of plants.

Originally Posted by Agemegos

Also, to disperse seeds and spores.

There is some benefit to pollinators, but you probably aren't introducing flowering plants until rather late. Basically, terraforming is trying to accelerate 2.5 billion years of development on Earth, and roughly 80% of that period was the Proterozoic.

[ericthered]

Originally Posted by Anthony

Why are you introducing herbivores? Really, if it doesn't contribute to binding carbon, all it's doing is slowing down the process.

Because we want trees reefs, and and actual ecosystem that won't get knocked over by the first invasive species. Sure, you can use microbial mats to get the atmosphere in place, but you'll want a multicelluar system at the end.

[Buzzardo]

For a related read, pick up Roger Zelazny's Isle of the Dead. The main character has the ability to create worlds that suit whatever his agenda at the moment is.