Australian Megafauna: Impacts on Soils

Ayrton

Ad Honorem
Jan 2017
4,268
Bendigo
We have to remember there are large areas in Australia that are fertile. A whole swath in NSW, where a huge amount of our produce comes from ( there is abattle on as they want to use this land for CSG - crazy .

Another example is the Dorrigo plateau in coastal central east coast. It probably had mega fauna and was burnt but it has high fertility for other reasons very specific to that area ( ancient basalt lave flows on surface, the plateau slopes back away from the escarpment ( unusual ) , high rainfall due to it being a far easterly extension of the 'Great Divide' (coast from inland , basically), so... high rain fall, low run off and erosion, basalt underlay + lotza years = 'krasnozem'






Which may look like , inland 'soil' but it isnt .

... and just down the hill near my place



Not dry or desolate at all!
Now, inland , and in other areas where those factors are different the soil is very infertile as its so old, worn out, leached, etc .

For the extreme. if one goes to the craton areas ... Pilbara, Yilgarn, etc . much more so .

https://en.wikipedia.org/wiki/Craton

This I think is the main reason a lot of Australia has such poor soils . Of course, continual fire, natural or spread by humans will have an effect , yet we have to realize, one of the main uses of fire stick was just not for 'farming' but to stop bigger more destructive burns gaining moment . So, without the fire stick management, the impact of natural fire may have been worse .

regarding animal manures, I remember from BD once we did a table of all different manures fertility , eg, chicken is high, cow, horse, sheep, is lesser but good, kangaroo is very poor. So unless we could access the quality off mega fauna poo-poo ..... ?

But I think the things I mentioned first , which basically boils down to geology and geography, would far outweigh the loss or gain from long term mega fauna - or not .

I guess the other thing to do is look at why the other areas ( like Great Planes in USA for eg) are fertile and how those soils were formed ... something I have little knowledge of .
Thanks, Specul8. (I have an urge to call you Specky. That way I can chat with Specky and Sparky on this thread.. which has a nice friendly feel).

I have a general point to make. Soils might be more stable in some areas than others, but if land is burnt often enough and long enough, and the manures being deposited (by kangaroos, as you mention) are ‘poor’, then soils will eventually erode away without much root growth to hold them. Where is your deep Permaculture and biodynamic and soil ecological understandings gone, son!? Just kidding.

But I do think stable soils are to do with deep roots. Whether trees or grasses, very broadly speaking, it’s the roots that matter, and deep ones.

Unless the burning is done right, eventually you degrade soils. I say this because deep soils produce regular and lush growth, even in dry seasons, and the plant species change through their cycles, but burns create green pick, the fast food of landscape (IMO). Green pick, all of sudden, makes me wonder if we are talking about monocultures?

If Aboriginal management of landscape created monocultures, whether green pick or swathes of semi-wild cereals, then disaster was coming, surely? It might have taken thousands of years, but it was coming. Modern monoculture farming destroys soils far quicker, but the Aboriginals took a softer approach and degraded soils more slowly?

The loss of megafauna could have played a part too, for whatever reason the megafauna disappeared, whether man-aided or cataclysm made.

I am thinking things aloud, not proclaiming an agenda, btw.

Did you perchance see my posts mentioning Elaine Ingram? I am keen to know if you are aware of her? And if not, if you are interested to watch one of her lectures on soils on YouTube? I have had an interest in soils (as a pure amateur) for a long time, but having watched some of her talks, I was amazed at her thoughts and investigations. She is not alone, but I was left with so much to think about after seeing one of her lectures. Just a thought. Her ideas inform much of what I am saying and much of my thinking about Australian ‘soils’. (Her lectures are specifically on soils as a living eco-system, not centred on particular landscapes).
 
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specul8

Ad Honorem
Oct 2016
3,413
Australia
Thanks, Specul8. (I have an urge to call you Specky. That way I can chat with Specky and Sparky on this thread.. which has a nice friendly feel).

I have a general point to make. Soils might be more stable in some areas than others, but if land is burnt often enough and long enough, and the manures being deposited (by kangaroos, as you mention) are ‘poor’, then soils will eventually erode away without much root growth to hold them. Where is your deep Permaculture and biodynamic and soil ecological understandings gone, son!? Just kidding.

But I do think stable soils are to do with deep roots. Whether trees or grasses, very broadly speaking, it’s the roots that matter, and deep ones.

Unless the burning is done right, eventually you degrade soils. I say this because deep soils produce regular and lush growth, even in dry seasons, and the plant species change through their cycles, but burns create green pick, the fast food of landscape (IMO). Green pick, all of sudden, makes me wonder if we are talking about monocultures?

If Aboriginal management of landscape created monocultures, whether green pick or swathes of semi-wild cereals, then disaster was coming, surely? It might have taken thousands of years, but it was coming. Modern monoculture farming destroys soils far quicker, but the Aboriginals took a softer approach and degraded soils more slowly?

The loss of megafauna could have played a part too, for whatever reason the megafauna disappeared, whether man-aided or cataclysm made.

I am thinking things aloud, not proclaiming an agenda, btw.

Did you perchance see my posts mentioning Elaine Ingram? I am keen to know if you are aware of her? And if not, if you are interested to watch one of her lectures on soils on YouTube? I have had an interest in soils (as a pure amateur) for a long time, but having watched some of her talks, I was amazed at her thoughts and investigations. She is not alone, but I was left with so much to think about after seeing one of her lectures. Just a thought. Her ideas inform much of what I am saying and much of my thinking about Australian ‘soils’. (Her lectures are specifically on soils as a living eco-system, not centred on particular landscapes).
I dont think I am familar with her work, but she looks familiar, sure I would be interested in checking it out , but I am sorta tied up with other things at the moment so not much spare time . ... unless it rains a lot, but we having a drought .

I became rather fascinated with soil micro biology, especially all those little critters that appear when one makes good 500 prep . I wanted to get them under a good microscope , but my research partner ( who had the large microscope ) ended up being a real dick and shut the project down ??? :zany: )

The whole thing emulated an alchemical process, and the little black, white and red 'bugs ' ?

Hmmmm ...




I also read a great book, whuch I cant seem to find or I.D. any more , I think it was called 'The Underground' about the whole underground ecosystem - fascinating ! One significant thing (population) that has caused BIG probs due to its removal was 'prairie dogs' / 'ground hogs' , fascinating reading section that !


Or we could experience the whole soil microbiotic world musically ..... :) .... via Vangelis




 

Ayrton

Ad Honorem
Jan 2017
4,268
Bendigo
I dont think I am familar with her work, but she looks familiar, sure I would be interested in checking it out , but I am sorta tied up with other things at the moment so not much spare time . ... unless it rains a lot, but we having a drought .

I became rather fascinated with soil micro biology, especially all those little critters that appear when one makes good 500 prep . I wanted to get them under a good microscope , but my research partner ( who had the large microscope ) ended up being a real dick and shut the project down ??? :zany: )

The whole thing emulated an alchemical process, and the little black, white and red 'bugs ' ?

Hmmmm ...




I also read a great book, whuch I cant seem to find or I.D. any more , I think it was called 'The Underground' about the whole underground ecosystem - fascinating ! One significant thing (population) that has caused BIG probs due to its removal was 'prairie dogs' / 'ground hogs' , fascinating reading section that !


Or we could experience the whole soil microbiotic world musically ..... :) .... via Vangelis




I really, really think you should sit back on the net one night and watch Ingram’s talk at Oxford. It will take up about an hour and a half - maybe before you go to bed. I have a feeling you’ll already know a lot about what she has to say, but my feeling is also that there will be things that might amaze you. (You can pop in here and abuse me if I predict wrongly!)

I thought I knew a good lot about ecology and the soil especially, but my jaw dropped a few times when I first heard her talk. You may have heard it all already, so I hope I am not encouraging you to waste any valuable time, but...

Btw she is a soil biologist and agricultural advisor and in no sense a hippy (it’s me who is the hippy....kinda...)

NB I am not trying to sign you up for a Cult either... but if you want me to, I could always start one. :)
 

Ayrton

Ad Honorem
Jan 2017
4,268
Bendigo
Salaminia and i were just having a chat over on the Dark Emu thread and it has got me really thinking... rather an achievement, when I think about it... well done, Salaminia, lol.

Pre-Aboriginal invasion of the Australian continent, did the megafauna roam over much of the continent? And did they live predominantly in a forested environment? Or were the soils here always rather on the thin side?

As a starting gambit, I offer the idea that forests were just about everywhere, but the soils - like in the Amazon basin - may have been thin, with most of the organic matter (carbon) sequestered in trees etc. and fauna (including megafauna, but of course!)

So, like cattle ranchers in the Amazon basin, could Aboriginals have gradually burned down the forests - or, to be more accurate, thinned our forests? Could this have destroyed a lot of megafauna habitat for a start?

Did Aboriginals come to Australia from slash-and-burn cultures north of the Australian continent, but because of the dryer weather regime here, the forests were changed and much was lost and thin soils exposed to the vagaries of the weather? And Salaminia mentioned the rise of the Eucalypt. Has a point.
 
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sparky

Ad Honorem
Jan 2017
5,248
Sydney
.
The way I see it , soil is an ecosystem which need moisture , no moisture ....poor soil

Australia land mass became progressively dryer ,

it is quite telling than the area of fertility are those where there is substantial rainfall
 
Mar 2015
873
Europe
.
The way I see it , soil is an ecosystem which need moisture , no moisture ....poor soil

Australia land mass became progressively dryer ,

it is quite telling than the area of fertility are those where there is substantial rainfall

Not actually the case.
Plants need water and nutrient minerals (like phosphorus, potassium and several microelements).


Water tends to wash away the nutrient minerals - "leach" them.
Much of Australia is flat and stable, with old rocks. A lot of the fertilizer minerals have been leached away over time, leaving just the insoluble rocks of little value to plants, such as silica.


Even when climate is wet, the fertility of soil makes a difference. For example, on east coast near Sydney, the Sydney sandstone gives poor infertile soils despite abundant rain. Nearby, in the same climate, the shales from Parramatta to Cumberland plain provide more fertile soils.
 

Ayrton

Ad Honorem
Jan 2017
4,268
Bendigo
This:
https://www.researchgate.net/publication/259043822_The_aftermath_of_megafaunal_extinction_Ecosystem_transformation_in_Pleistocene_Australia
from Lynch Crater in Queensland, suggests that decrease of big grazers caused increase of fire.
Great article. Whether completely on the money or not, it certainly matches just about exactly with my speculations. Not sure if that is good or bad, but it certainly encourages me to think I might not be alone in what I suspect.
 

Ayrton

Ad Honorem
Jan 2017
4,268
Bendigo
Not actually the case.
Plants need water and nutrient minerals (like phosphorus, potassium and several microelements).


Water tends to wash away the nutrient minerals - "leach" them.
Much of Australia is flat and stable, with old rocks. A lot of the fertilizer minerals have been leached away over time, leaving just the insoluble rocks of little value to plants, such as silica.


Even when climate is wet, the fertility of soil makes a difference. For example, on east coast near Sydney, the Sydney sandstone gives poor infertile soils despite abundant rain. Nearby, in the same climate, the shales from Parramatta to Cumberland plain provide more fertile soils.
I am interested on subjects like Permaculture and Holistic Management - and soils generally. I know I keep bullying Specul8 about watching Dr Ingram (soil biologist and agricultural advisor) on YouTube, but I think, for me at least, she clinched it on what makes soils function.

So when we talk about ‘infertile’ soils I immediately think about ‘primary material’ which we might think of as almost biology free ‘dirt’. Bacteria and viruses may exist, but not much else. Add organic matter and we begin to get soil. Some moisture and not too much freezing, and add larger forms of biology + including, one imagines, megafauna cycling - and you build deeper humus filled soils (both carbon sequestation and cycling through biology).

So nowadays when I see desertification, I tend to see a lack of megafauna both cycling carbon and helping set carbon storage in soils. I wonder if the Sahara and other deserts are, so to speak, man made, due to over hunting of megafauna and, in many places, extinction of megafauna through agriculture, especially noticeable in places like ancient Mesopotamia. The American prairies are turning back to ‘dirt’ as modern farming methods inexorably denude carbon (in all forms, living and decaying and stable) from the soil.

Anyway, thanks for your link. Plenty of food (carbon, lol) for thought!
 
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Mar 2015
873
Europe
Some moisture and not too much freezing, and add larger forms of biology + including, one imagines, megafauna cycling - and you build deeper humus filled soils (both carbon sequestation and cycling through biology).

So nowadays when I see desertification, I tend to see a lack of megafauna both cycling carbon and helping set carbon storage in soils.

I think that phosphorus cycle is more vital than carbon cycle. Carbon is renewable because it is taken up from carbon dioxide in air. Phosphorus is not.


One thing that was problematic in Australia is fire regime.


When plants grow plant matter, there are three things which can happen to them:

  1. They may be eaten by large animals
  2. They may die and rot, meaning they are eaten by small organisms such as bacteria and fungi
  3. They may burn
There are vegetation types in Australia that do not easily burn.
Rainforests do not easily burn, because the plants are always wet, alive or dead. So the wet dead plants rot and do not burn.
But deserts also do not easily burn. The scattered plants in desert die and dry but they are so far from each other that even if one dry plant were burned, the fire would not spread to others. Even over time, as new plants sprout and die between old dead plants, the old dead plants somehow decay in desert, so that they do not accumulate enough to spread fire.


So fire needs seasonally wet and dry climate, with enough rain to support dense vegetation, but then enough dry weather for the dead plants to dry.


But even then, it depends on the specifics of vegetation.
For example, in semiarid climate, grasslands grow grass which dries up and burns well.
But in also semiaric climate, the vegetation might consist of succulents, like cacti of America or spurges of Africa.
Cactus scrub will not burn easily. A live cactus may be scalded or killed by fire of dry plants next to it, but then it would give off just steam and smoke, rather than catch fire.

A dead cactus would also tend to rot rather than dry. Even if a few cacti in a scrub are dead and dry and able to burn, with only a few recently dead cacti being dry and flammable, a cactus scrub might not support a fire.


There are some succulents in Australia - but rather few. Not as prominent as cacti of America or spurges of Africa.