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Soil Animals & Global Warming

The Soil has a major role to play in Global Warming, as it holds more carbon that the vegetation and air combined. Yet, it doesn't appear to be factored into any governmental initiatives to hold/sequester carbon on the soil - see 'Save our Arable Soils'


This is how it works, although we are only starting to understand the role soil animals play in making the soil web work. Soil animals play a key role in moving carbon around in the soil. UNFCCC video shows importance of carbon in the soil. See role of soil animals in cycling soil carbon. They played an incredible role keeping carbon dioxide levels low when soils evolved in Devonian times.
Soil Carbon

This page is largely based on this paper
'Biotic interactions mediate soil microbial feedbacks to climate change


This long-term study showed that small soil surface animals can limit the effects of global warming. That sounds quite insignificant, yet may be one of the most important aspects to factor in.to Global Warming calculations*. 

The Intergovernmental Panel on Climate Change projections factor the land into their calculations. But they are predominantly physically and chemically based. In 10.4.1 they say there is "There is unanimous agreement among the models that future climate change will reduce the efficiency of the land and ocean carbon cycle to absorb anthropogenic CO2" (that means chemicals made by humans - in particular carbon dioxide and methane). They believe that increased global temperatures will lead to more carbon dioxide gases released from the soils.


Role of Microbes
Decomposition of organic material by soil microbes generates an annual global release of 50–75 Petagrams of carbon to the atmosphere. in the form of carbon dioxide and methane (1 Petagram equals 1 billion metric tons). To make sense of that, this is nearly 10 times more than all human derived emissions. So, what goes on and in the soil is vitally important, and ignoring the role of 12 Quadrillion soil animals could make all the difference. The trouble is we don't know what is going under our feet, when it comes to factoring in the life in the soil.

The microbial processes, those fungi and bacteria that are digesting bits of debris making chemicals are sensitive to global change factors, meaning they when it gets warmer, they are likely to produce even more Petagrams of carbon gases. This will drive carbon cycle–climate feedbacks with the potential to increase still further atmospheric warming.

While we know that global warming has the potential to accelerate the microbial is processes, leading to increased carbon emissions that will accelerate climate change through a dangerous feedback cycle, little has been known about which ecosystems will be most affected and why. What role may soil animals play. After all they were pretty important 350 million years ago in making the atmosphere for higher plants.

The study 
We need the microbes to digest the debris. But the microbes fart out some of the end products. Instead of this going to air, the creatures are eaten and the carbon saved. It is the next stage in the feeding levels that  other predators benefit from , and enable to world to go round. 

An international collaboration between researchers at the Yale School of Forestry & 
Woodlice collecting
Environmental Studies (F&ES), the University of Helsinki, the Institute of Microbiology of the ASCR in the Czech Republic, and the University of New Hampshire -- was designed to shed light on this issue.They found: "In disturbed environments, where soil animals are not present, the feedback between climate change and microbial carbon production was strong, yet, when the soil community is healthy and diverse, we saw that animals feed on the microorganisms, limiting the feedback effects." The soil animals they studies were Isopods, we know better as 'woodlice' You may see them under piles of stones and they feed on fungal remains and other microbes.          
Collecting Woodlice

Microbes, when warmer and better food supply (nitrates), will increase so produce more carbon dioxide and methane gas, both released into the atmosphere and contributing to global warming. If, however, there is a good range of soil animals, some will be eating these microbes, controlling their numbers. More importantly for us. this means the carbon that would have gone up into the air, now goes into the animal's bodies. And then their predators bodies. And so on up the food chain to beetles, ants and birds. Again the role of soil animals seems v important in global warming, but virtually unrecognized. 
This "top-down" control matters only when there are no limitations to the production of nutrients at the bottom of the food web. These would occur as a result of global warming. One of the authors said. "As a result of climate change, there's going to be more nitrogen deposition, it's going to be warmer -- many of the things that limit fungal growth are going to be alleviated," he said. "And by stimulating microbial activity it will trigger higher carbon emissions. So when those 'bottom up' limitations are gone, the grazing animals become even more important."
Plots and PotsSo they checked out the role of the grazing animals - woodlice, by setting out plots with various combinations of warmth, nitrate and isopods. They found that when the soil is warmer and has nitrate feed, the isopods were very successful at keeping the microbes,measured as fungal cords, under control
Fungal Cords
In the graph below, the cords with no isopods (2nd left) were much much taller in N and W&N than those with cords and their predatory isopods (far right). This means that soils with woodlice do not send so much carbon gas into the air.
Woodlice graph

I wonder how much that graph adds up to across the world? The microbes - while doing an essential job, produce the carbon gases. While to soil animal do an even more important job - they get hold of that carbon and recycle it. When they are eaten, that carbon goes in the prey, and so on up the food chain. 

Put simply microbes increase carbon dioxide (and methane) emissions, while soil animals reduce them. Is there any way of quantifying this? 

Significance

This study shows how we need to look at the interactions between soil organisms, and we have many more to look at. They looked at isopods - woodlice, snuffling over the surface nibbling fungal cords. What if we could do the same sort of trial and include Springtails and Oribatid. How much do they contribute to reducing the 'land carbon–climate feedback' as it is known?

Surely this should be incorporated into the earth system models that inform current Intergovernmental Panel on Climate Change projections. How much do those 12 Quadrillion of these creatures in Britain 'hold; in terms of carbon in the soil? Probably similar to earthworms, if CEH study anything to go by. We saw in CEH study that soil mesofauna moved more carbon around than worms. Together they will be vital to control our earth's temperature. But both store - how much? We don't mention them in all those grandeous schemes. 

The results raise doubts with the use of 'Soil Organic Matter' (SOM ) as our preferred measure of soil activity. Quite simply, SOM is dead matter. Wheras this study showed the importance of factoring in live animals. The study highlights the importance of understanding biological processes if scientists are going to be able to predict the consequences of climate change, said Hefin Jones, a professor at Cardiff University and a leading expert in climate change research. He was not affiliated with the study. "Our current understanding of carbon cycle feedbacks to climate change stem mostly from the physical sciences; this study shows that precise global predictions can be achieved only if we understand the interactions between organisms", 

James Lovelock, was the man who  created the Gaia hypothesis.  (New Scientist). This hypothesis  proposes "that organisms interact with their inorganic surroundings on Earth to form a synergistic self-regulating, complex system that helps to maintain and perpetuate the conditions for life on the planet" I saw him speak at the Hay Literature Festival a few years back, and in answer to a question asking how his Gaia theory fitted with climate change modelling , said (something like): 'the trouble with all the climate change models is that they are only physico-chemical, and that the living components are not yet computed in'. We need to add the ‘biological’ into those algorithms, and the soil biology will be the biggest input.
Is the relationship between certain soil animals (eg woodlice and Springtails) and microbes an example of "the ability to self-regulate critical systems"?
Luckily a few decades back, there were soil scientists looking at this sort of stuff. Springtails and Funghi.

What relevance does this have to Soil Health Indicators? Should we use Woodlice? They tell us there is a healthy microbe population out there - which needs a bit of controlling.

NB I use the words 'Global Warming' rather than the more popular 'Climate Change'. We can measure the globe warming, but have difficulties predicting the resulting change of climate.
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