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Soil Evolution
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  • 500-400 mya
    • No Soil
    • 4.500 - 1000 mya
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    • Periods
      • Cambrian
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    • Biology
      • Plants
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  • 400-300 mya
    • 400-360 mya Late Devonian
      • Green cover
      • Vascular Plants
      • Mycorrhiza (AMF)
      • Animals
        • Springtails
        • Arachnids
    • 360-300mya Carboniferous
      • Plants
        • Vascular
      • Early Soils
        • Micro-aggregation
      • Animals - Early Carb
        • Oribatids - Lower
        • Origin of Insects
      • Animals - Late Carb
      • Worms
  • 300-200 mya
  • 200-100 mya
    • 200-145 mya Jurassic
    • 145-66 mya Cretaceous
  • 100mya - 0 mya
    • 66 - 0 mya Cenozoic
  • Now
    • Present State of Soil
      • Desertification
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    • Save our Soil!
      • Soil Health
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Soil Evolution
  • Home
    • Start
      • Soil & Civilisation
      • Seeing Soil
      • Soil Science
      • New Science
      • Short story
    • What is Soil?
      • Clay
      • Soil Structure
      • Biome
      • Glomalisation
        • Testing
      • Soil Functions
        • Energy
          • Entropy
      • Decomposition
        • Mineralisation
        • De-lignification
        • Humification
      • Types
        • Europe
    • Challenge
      • Terrestrialisation
      • Theories so far
      • Tools
    • Darwin's version
    • Timeline
      • Copy of 100mya - 0 mya
      • Copy of 200-100 mya
      • Copy of 300-200 mya
      • Copy of 400-300 mya
      • Copy of 500-400 mya
  • 500-400 mya
    • No Soil
    • 4.500 - 1000 mya
    • 1000 - 500 mya
    • Periods
      • Cambrian
      • Ordovician
      • Silurian
    • Biology
      • Plants
      • Animals
      • Bacteria
  • 400-300 mya
    • 400-360 mya Late Devonian
      • Green cover
      • Vascular Plants
      • Mycorrhiza (AMF)
      • Animals
        • Springtails
        • Arachnids
    • 360-300mya Carboniferous
      • Plants
        • Vascular
      • Early Soils
        • Micro-aggregation
      • Animals - Early Carb
        • Oribatids - Lower
        • Origin of Insects
      • Animals - Late Carb
      • Worms
  • 300-200 mya
  • 200-100 mya
    • 200-145 mya Jurassic
    • 145-66 mya Cretaceous
  • 100mya - 0 mya
    • 66 - 0 mya Cenozoic
  • Now
    • Present State of Soil
      • Desertification
      • Concretisation
      • Globalisation
    • Practices affecting Soil
      • Chemical
        • Fertilisers
        • Carbon
        • Pesticides
      • Problem
      • Biological
    • Soil & Global Warming
      • Soil Surfaces & Global Warming
      • Soil Carbon
      • Soil & Water
      • Soil Temperature
      • Soil Biota
      • Climate Change
    • Save our Soil!
      • Soil Health
      • Regenerate
      • Ecology
      • Economics
  • More
    • Home
      • Start
        • Soil & Civilisation
        • Seeing Soil
        • Soil Science
        • New Science
        • Short story
      • What is Soil?
        • Clay
        • Soil Structure
        • Biome
        • Glomalisation
          • Testing
        • Soil Functions
          • Energy
            • Entropy
        • Decomposition
          • Mineralisation
          • De-lignification
          • Humification
        • Types
          • Europe
      • Challenge
        • Terrestrialisation
        • Theories so far
        • Tools
      • Darwin's version
      • Timeline
        • Copy of 100mya - 0 mya
        • Copy of 200-100 mya
        • Copy of 300-200 mya
        • Copy of 400-300 mya
        • Copy of 500-400 mya
    • 500-400 mya
      • No Soil
      • 4.500 - 1000 mya
      • 1000 - 500 mya
      • Periods
        • Cambrian
        • Ordovician
        • Silurian
      • Biology
        • Plants
        • Animals
        • Bacteria
    • 400-300 mya
      • 400-360 mya Late Devonian
        • Green cover
        • Vascular Plants
        • Mycorrhiza (AMF)
        • Animals
          • Springtails
          • Arachnids
      • 360-300mya Carboniferous
        • Plants
          • Vascular
        • Early Soils
          • Micro-aggregation
        • Animals - Early Carb
          • Oribatids - Lower
          • Origin of Insects
        • Animals - Late Carb
        • Worms
    • 300-200 mya
    • 200-100 mya
      • 200-145 mya Jurassic
      • 145-66 mya Cretaceous
    • 100mya - 0 mya
      • 66 - 0 mya Cenozoic
    • Now
      • Present State of Soil
        • Desertification
        • Concretisation
        • Globalisation
      • Practices affecting Soil
        • Chemical
          • Fertilisers
          • Carbon
          • Pesticides
        • Problem
        • Biological
      • Soil & Global Warming
        • Soil Surfaces & Global Warming
        • Soil Carbon
        • Soil & Water
        • Soil Temperature
        • Soil Biota
        • Climate Change
      • Save our Soil!
        • Soil Health
        • Regenerate
        • Ecology
        • Economics

400-360 mya Late Devonian

Plants Mycorrhiza Animals Springtails Arachnids Green Cover

400-360Mya

Over the next 40 million years, all sorts of animals started running around, feeding around plant roots, thereby sucking energy into soil.  In so doing, they created materials that helped the parts - plant animal and mineral - stick together to start making soil.  The key development for this is the tri-relationship between roots, fungi, and springtails. 

400-360mya Mid - Late Devonian

Green Covering

Over the next 40-50 million years or so, soils evolved to cover some of the planet. We have seen that small plants, like bryophytes were already growing. Up till this time, the roots tried to cling to rocks, but now they could go deeper into the sediments. 

I propose that a litter layer was formed at this time, of moss and other bryophytes debris, which was not decomposed much, but provided a canopy for roots to start growing outwards. In turn these provided a new environment - rhizosphere for, for creatures to dwell in. The new undergrowth would be much like those on old stone walls where lots of ferns grow, creating a new environment. Trees started to appear.

400-360Mya
Early Soil
Litter layer
Histosol
Shallow Soil
Litter roof

Well-preserved assemblages of soil organisms are few and far between because soil environments are generally not preserved – the conditions for undisturbed burial and preservation in the geological record are few and far between – the percentage of the stratigraphic column containing fossil soils (palaeosols) is very very small. Some creatures, despite looking well armoured. dont fossilise well. However, we do have a treasure trove for this time, as we will see - in the rocks at  Gilbao

Mike Benton said “Various plants had crept onto the land and a very minor way long before with quite a debate among paleo botanists and others to determine absolutely when plants first began to green the landscape. Conditions were warm, but there wasn't a great deal of food, because it was just bare rock and without much soil. Plants had to conquer a couple of things. One of course was if you creep away from the water a bit too much, you've got no water. And if there's not much soil, how on earth do you develop roots, and how is water stored and how do you obtain it."

Cooperative evolution

There is general recognition that there was a co-evolution of plants and soil around this time. But there are lots more characters working together for that to occur. One group helped plants grow, while another group started on the decomposition process.

Here are the key characters, bacteria, fungi, with plants and animals, that were working together on the new processes which created the soil, its spaces, structure and roof.

Growing

One key  relation is that between plant roots and fungi, we call mycorrhiza . Also, involved in the same new 'rhizo' sphere were lots of legged creatures - called arthropods - running round eating and pooing. The fungi, bacteria and the basic plants were all spread by spores - there were few seed bearing plants then.  The new found relations with arthropods, like springtails, helped disperse this new life grouping across the surface of the planet.

Decay

The other relationship involved the dead plant parts that were being broken down by bacteria and saprophytic fungi, see below.. The smaller dead plant parts provide food and energy to some of the creatures which were detrivores, like millipedes.

Early Soil

In a study by the UK's Natural History Museum  of recent soils in order to try and understand fossil soils, researchers found support for their theory that early (400mya) soils were:

Formed of communities of cyanobacteria, fungi, lichens, small rootless plants

mostly thin (millimetre and centimetre scale)

inhabited by diverse but minute arthropods

already host to sophisticated symbioses among fungi, cyanobacteria, algae and plants”

Present-day clubmosses in extreme conditions. like 400mya

Bacteria

“There are numerous ways in which bacteria can interact with clay minerals and alter them: dissolution, refinement and transformation, reduction of trace elements incorporated in the clay minerals and uptake of trace elements from these minerals…In addition, bacteria can influence layer charge, cation exchange capacity (CEC), exchangeable cations, Brunauer–Emmett–Teller surface, swelling and the rheological properties of clay minerals. The field of clay mineral–microorganism interaction is still wide open” (Retallack, 1992) 

While we have seen that bacteria have been present since3.5 billion years ago, it was probably around 400mya they came into their own in soil (Wellman and Gray, 2000). They would have been creating those cation chemical pathways, still so important to this day. They help make nitrogen and phosphate more available to plants. Those phosphate solubilizing bacteria (PSB) provide sparingly available phosphorous compounds that fungi can utilise, to help feed into plant roots.

Saprophytic Fungi

Two sorts of fungi had emerged - those living with roots called mycorrhiza and those living on dead stuffs, saprophytic fungi. These are the ones we are most familiar with - as they send up 'fruiting bodies'. They live aerobically and produce enzymes that allow them to decompose the tough plant cell wall compounds: cellulose, hemicellulose, and pectin. 

Many now also decompose lignin, but was that ability around 400mya? As we are finding with other early living groups, the evolution of these fungi is not straightforward. "After arbuscular mycorrhizal fungi were segregated from zygomycetes into the new phylum Glomeromycota, (Schubler et al 2001) zygomycetes became paraphyletic (Spatafora et al 2017)(Hibbert et al 2007) (Li et al 2021). In other words they arose several times from various sources.

"Saprophytic fungi have been divided into three main groups: (i) white rot fungi, (ii) brown rot fungi and (iii) soft rot fungi. ...All these types of fungi are able to decompose lignin, but only white rot degrade it completely to CO2 and H2O (Blanchette 1995)." (Janusz 2017)
ChatGPT says the common understanding is that "the chronological order of evolution would likely be: Soft rot fungi first, followed by brown rot fungi, and finally white rot fungi. However, the precise evolutionary timeline of these fungi is still an area of active research and may be subject to revision as new evidence emerges"

I believe (to be proven!) that early saprophytes had limited decomposition  powers, mainly to cellulose and pectin, but  lignin decomposition was later, and that delay had major consequences in the years ahead. See Quirk

Plants

Liverworts and mosses had been joined by ferns and horsetails as well as seed-bearing plants called gymnosperms, like conifers and ginkgos. They covered more land, trapping more energy from the sun.

Their roots would have been shallow and their debris would have been predominantly cellulose with little lignin. More on plants

Arthropods

Small legged creatures were running round, probably passing spores, but also eating fungi and debris, and pooing out the remains, which happen to be adhesives sticking various bits of debris and minerals together.

The three key small animals are all over the world are the springtails, mites and nematode 

Many of them are considered to be ‘generalistic’, in that they may have a primary preference for what to eat but will eat alternatives. While some are predominantly fungal eaters, they can change to eating debris and are not that fussy. They can make do with a wide variety of food, rather than specific to a particular group. This has stood many early soil inhabitants well over many difficult years. 

Some springtails look like living fossils from 400 mya. The mycorrhizal fungi are found on 80% of plants roots. These processes are much the same today, while roots and environmental conditions have changed. It is probably the most important process ever of life, having evolved all this time ago, adapted throughout hundreds of millions of years, and today hold the key to improve soils. Animals

3-way process

The 3-way process between roots fungi and springtails is the most important building process of the soil and emerged during this period. It is aerobic requiring oxygen to function. All else has been built upon it, and it is still today one of the most vital life processes on earth. 

Roots of plants produce exudates which make their surrounding attractive to mycorrhizal fungi. Root exudates may act as signals for microbial recognition. Some’flavonoids’ may be suppressors of certain pathogenic fungi. Root exudates can also indirectly suppress pathogens by attracting antagonists of plant pathogens. Strigolactones are carotenoid-derived signalling molecules and released from roots that enable symbiotic fungi to detect their host plants and have been identified in AM fungi and can induce AM spore germination and hyphal branching (Marschner, 2019). 

The fungal filaments provide the roots with much more water and nutrients particularly phosphates. In return the roots provide the energy for fungi. The fungi produce glomalin, discovered about 30 year ago, which makes up a quarter of all soil carbon, and is the main food for springtails, often around 100,000 per sqm. This vast number chew the glomalin and poo it out as glomalin related soil proteins (GRSPs). This spreads the carbon compounds, captured in the leaves conducted into the roots, throughout the soil. The springtails also help distribute the fungal spores and keep the roots clean of dead fungal matter.  GRSPs are gluey substances which bind together various mineral and vegetable particles to make the aggregates which provide the pores for life and holding water.

Spores

Spores are the main spreaders for plants fungi and bacteria. Spores are asexual and take less energy to produce than a seed. Spores do not vary a lot, but in those times, it did not require variation to adapt to conditions because there was a lot of land open to anything which could survive. The distribution of spores – of plants, fungi and bacteria, must have been monumental. The structure of these spores must have been crucial in order to spread the message across this bare planet. They would be distributed by water and wind.

Spores are also involved in setting up the relationship between roots and fungi. How do fungal spores travel to reach the roots? What are the mechanisms underground? Perhaps some of those arthropods running round helped. From woodlice scuttling along, slugs slugging it out, springtails springing, and mites doing their mighty thing this army on the move could move spores. There were no high fliers, just movers and shakers. We have seen that springtails can detect bacterial spores, but that is for food. Could the larger fungal spores be carried? When the fungal spores landed and grew into the roots, they would grow hyphae which expand what roots could do.

Pores

As peds arrive, so do spaces beteen them - pores. These provide a new - albeit small, environment for creatures to live in. In this new world, there are lots if new questions:

How is microbial dispersal influenced by the pore spaces being filled with air, water, or nutrient medium? 

How does pore space geometry affect microbial dispersal, such as channels angled in zigzag patterns, forcing the microbes to navigate through increasingly sharper turns? 

Are bacteria and protists influenced in their dispersal capabilities to new pore spaces by the presence of a fungal hypha? 

How does drying and rewetting soil, and the moving and growing microorganisms, affect the spatial arrangement of the chips’ pore space? 

To answer these questions, electronic chips have been made to replicate the pores. "Both soil microbes and minerals enter the chips, which enables us to investigate diverse community interdependences, such as inter-kingdom and food-web interactions, and feedbacks between microbes and the pore space microstructures.
"Our experiments show that water and nutrient conditions mainly affect water-dwelling organism groups of bacteria and protists, while the shape of the microstructures has an effect on fungal dispersal. Fungal hyphae strongly enhance the colonization success for both bacteria and protists in an initially dry pore space via increased pore wetting. The chips also reveal spatiotemporal changes of microhabitats: hyphae both open up new passages in the pore space system and block them for both organisms and abiotic soil components. Water movements, triggered by drying and rewetting the soil, lead to the development of preferential water pathways that differentiate microhabitats further" (Mafla-Endara et al 2021). 

Structure

To have pores, there has to be a structure. "Across the DFS (distributive fluvial system)  there is evidence of plant-sediment interactions in the form of vegetation-induced sedimentary structures, rooting features, and accumulations of plant debris. Plant remains are also found in nearshore facies adjacent to the DFS, attesting to the development of a novel non-marine/marine teleconnection from the production and export of new biological sedimentary particles. The Hangman Sandstone Formation is illustrative of the revolutionary power of cladoxylopsid trees as biogeomorphic agents, forming densely spaced forests and shedding exceptionally abundant plant debris, whilst also impacting local landforms and sediment accumulations and profoundly changing landform resilience against flood disturbance events. These findings provide evidence that the Eifelian Stage (393.3-387.7 Ma) marks the onset of tree-driven changes to physical environments that would forever change Earth's non-marine landscapes and biosphere...The debris thus appears to be a passive accumulation of shed woody material of uniform taxonomy of the former sediment substrate, with limited interaction with classic sedimentary particles and having nit experienced orientation of flowing water. ". Davies 2024 

"Clastic sediments are predominantly clay minerals and quartz particles, with minor amounts of Feldspars, micas, and heavy minerals. Porosity results from the space between the grain particles that is not filled with cement or clay. Porosity is usually in the range from 10% to 30% depending on the grain sizes, compaction, and the amount of cement present between the pores. Permeability, which is the property that permits fluid to flow through the pores, is controlled by the amount of cement, the degree of compaction, and the magnitude and variation of grain sizes." Aminzadeh 2013 

Litter layer

We now know the litter layer has been here for that time. When I say ‘litter layer’ than can be quite thick. It could include peat like substances. You could imagine mosses on peat – much like sphagnum moss on peatbogs today. Basically the ‘soil’ then is the equivalent of what we now call Horizon O. That litter and plant cover would start to protect what is going beneath. Many other developments of soil must have happened below that litter – without affecting it. Which is handy, as it means we can look at what a litter layer or peatbog is doing now, to predict back to earlier times.

This thin skin of litter is what starts to makes lumps of life, not sand, silt or clay. It is a magical mix of minerals and matter, created by life forces. This is the stable environment, that survives extremes, even mass extinctions, to protect soil development below.

Histosol

This may be the period we recognise the first signs of soils as we know today. One of the first soil types to appear and properly classified in the soil Order, is called Histosol (from the Greek histos – tissue), dominantly composed of organic material in their upper portion. The Histosol order mainly contains soils commonly called bogs, moors, or peats - all places where plants have not decomposed. These soils form when organic matter, such as leaves and mosses, decompose more slowly than it accumulates due to low microbial /fungal decay rates. The growing is doing better than the decaying, and the result leaves a litter layer.

Shallow Soil

This was the period when that fabulous construction for soil - aggregates developed. Debris and minerals mixed with fungi and bacteria and provided lots of new surfaces for life. The poo glue of springtails provided glue to build these aggregates. This shallow soil provided homes of strong structure with their rooms (pores)  for small creatures to live in, without being crushed.  While always changing, it was also very stable, compared with life above ground. 

Extinctions

There are three important extinctions in latter half of the Devonian Period, each separated by about 10 million years. There was the Kellwasser event around 370 mya and the Hangenberg Event around 360 mya bringing losses of at least 20% of families and 50% genera, mainly marine life. 

It is estimated that some three-quarters of all living species did not survive. What caused this massive loss of species diversity, one of only five such crises in geologic history? Was it global cooling? A catastrophic impact, or several impacts? Palaeontologists cannot agree. Based on two decades of research this book reviews the many theories that have been presented to explain the event, considering in particular the possibility that the extinction was indeed triggered by the multiple impacts of extra-terrestrial objects”

Which of our new found soil friends did not survive? How did many survive? And what changes occurred to others? We shall see..

Litter roof

The un-decomposed litter may well have protected soil's early shallow development.  The litter provided cover and support for the new structure in which organisms could adapt. It has housed some ‘living fossils’ for four hundred million years.  What are ‘living fossils'? How come they could be living then and now still look ery much the same? There is only one answer. The environment must have stayed the same. If the environment had changed, then according to Darwin’s theory, organisms would have been selected that better fitted the new environment. Clearly that did happen, but it also shows the soil litter organisms – the mycorrhiza, springtails and millipedes - that are much the same today show how some environments have stayed the same. Some of their mates went off and evolved into other forms, but a massive body of them remained in this stable environment. So we can look at this environment today to work out what went on all those years ago.

Plants Mycorrhiza 

Animals Springtails Arachnids Worms

Next Period 360-300 mya Carboniferous

DONT FORGET 'Thin Skin' from the book at this time.

This site is set up by Dr Charlie Clutterbuck
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