soil biota research paper

8/7/2019 Soil Biota Research Paper

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SOIL BIOTA AND ITS RELATION TO THE ABOVE VEGETATION

Nicolette Casselli

Raymond Meuller

Soil Science


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Soil science is a fairly new and exciting field of study. There is still so much to be

discovered about what is going on below our feet. There are so many different complex

structures that form within the soil that we dont even take into consideration i n our daily lives.

There are microscopic connections made between the organisms in the soil that we wouldnt

even consider to be possible without much experimentation and observation. Its so hard to

collect this data, however, because some of these organisms live much further below the ground

than the average human is able to venture. New studies and technologies, however is allowing

the scientists of today to take a closer look at the organisms that make up these complex

connections in the soils. Some may even be the great ancestors of the origin of life itself.

Needless to say, all the living things within the soil effect what we see at the surface. Some are

microscopic and some are giants comparatively, but all are important, and all have their own

things to add to the soil that contains the life above. Two-thirds of the Earths biological

diversity lives in its soils and underwater sediments, and thriving underground communities keep

the planets surface green and habitable (Baskin 2005). Soil biota plays an important role

within the ecosystems of the earth, and learning more about these life forms will help us further

understand how to use the land sustainably and keep our Earth a healthy planet.

When most people think about where terrestrial life began, they think of a slimy blob

emerging out of the bubbling ocean. A new theory is forming, however, where microbes on clay

particles are the origin of life on land. As the Earth cooled and its heat was contained within the

land masses, microbe organisms began to form. The electrostatically charged surfaces of clay

minerals served as primitive enzymes and provided the catalytic sites of Earths first complex

biosynthesis. (Wolfe 2001). Basically, the clay crystals became low-tech genes that could

replicate themselves. As evolution went on and on, these macromolecules became more


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complex and and began to branch out into individual forms of life without using the clay particle.

This theory comes from the fact that clay particles

themselves are very complex crystalline structures.

They obtain charges from the atoms that are

attached to their surfaces. These charges can

change the characteristics of the clays themselves

and affect the chemistry of the surrounding

medium. (Wolfe 2001). The charges also attract

things like amino acids (proteins) and nucleotides

above is a picture of a clay crystals fromwww.corelab.com

which are parts of DNA and RNA. To support this theory, in the 1990s J.P. Ferris and his

colleges managed to attach nucleotides together in long chains using montmorillonite clays as

catalysts. (Wolfe 2001) They were able to do this because some clays can store the chemical

energy needed to support life.

Another support of this theory could be seen by the way a clay is structured. These

structures have irregularities which can be seen as mutations the way real genes have

mutations, which are an important part of the evolutionary system. The first real concrete

evidence of bacterium living at high temperatures deep under the ground was in 1965 with the

discovery ofThermos aquaticus that could live in 176 degrees Fahrenheit in the hot springs of

Yellowstone National Park. During the 1980s was when further research on these

extremophiles really took off. As time went on, scientists were discovering organisms that

didnt need oxygen to breath and instead were using carbon (Wolfe 2001). The habitual zone
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for life to form now changed because of these heat-loving bacterium. Therefore, the thought

of soil as being the crucible of life can be taken quite literally these days.

Weather life began in the soil or in the ocean, the important part is the complex networks

that it has made within our current evolutionary time. Of course, learning the history of where

life came from is important, but most people are living in the now and need to know how best to

work their land. What many dont realize is the importance of the living things, both seen and

not seen, within the soil. These tiny organisms living beneath our feet do more than we

understand, and trying to preserve these networks is our best chance to create a healthy and

sustainable method for using the land. Many different organisms live within the soil, but some

important ones include bacteria, nematodes, earthworms, and fungi.

Bacteria play a major role in breaking down organisms into materials that plants and insects

can use as nutrition. For example, the nitrogen that is needed for legumes is mostly made by the

bacteria living at their roots. The relationship between the bacteria and

the legume plant is symbiotic, or mutually beneficial. These special

groups of prokaryote are also called nitrogen fixers and are very

important within the soil community. The evolutionary invention of

nitrogen fixation ranks with photosynthesis as one of the cornerstone

events in the history of life on Earth. (Wolfe 2001). Through many

evolutionary processes, legumes finally obtained a genetic code that

attracted these nitrogen fixers. Once the bacteria reach the legumes, they

make a home in the roots of the legumes and they both join in making a

casting (nodule) over the bacteria too keep out predators and for theabove is a root nodule of a legume p

atwww.paintthelight.net
http://www.paintthelight.net/http://www.paintthelight.net/


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legume to benefit from thebacterias ability to break the strong triple bond of the N gas pulled

from the abundant supply in the atmosphere. The excess useable nitrogen is either lost to the

Nitrogen Cycle, or it is used by other plants at a different time. This is why crop rotation with

legumes is an important part of agriculture. The bacteria also work as great decomposers of the

organic matter rotting at the surface of the soil. Their waste is another part of the nutrient

cycling (Baskin 2005). The Earth is not constantly making new Nitrogen or Oxygen atoms.

There is a vast recycling of all these elements that are needed for sustaining the life on the planet.

Bacteria are one of the organisms to participate in a vital part of nutrient cycling.

Nematodes are also very important of the nutrient cycling process. Like many

organisms, there are both beneficial and harmful kinds of nematodes. Nematodes are microbe

munching roundworms about 1/20th

of an inch longand are the most diverse and abundant

animals on the planet. (Baskin 2005). They break down the fungi and bacteria microbes that

harbor many of the key nutrients in the ecosystem which speeds up the nutrient cycling for plants

and larger organisms. Since they are such a large part of the soil ecosystems, losing them would

be detrimental to the soil health. They release so many locked up nutrients to the species around

them. Without them, the nutrient cycling would be much slower and most plants wouldnt even

have a chance at survival in most areas. Nematodes also keep the bacterial and fungal

populations in check. This is a good example of how diverse ecosystems are important because

if there is too much of one thing, the balance is thrown off and the ecosystem is destroyed.

Therefore, too much of bacteria is a bad thing as well as too many nematodes, but the right

amount is healthy.

Fungus has a surprising role in the soil. Someone walking through the woods and finding

a mushroom sitting below a tree would think that this is the largest and most important part of


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the organism. They would be wrong, of course, because there is a whole network of roots

from that fungi extending below the ground and connecting various plants together. These roots

are really called mycorrhizae and they are very fine hair-like structures that extend within the

soil searching for nutrients and anchors to connect to. The fungus above the ground is the

reproductive part of the organism and is not always seen. These mycorrhizae can be attached to

several different plants at once, and not all the same species either. Most of this fungus can be

good, but some may be infectious. The good fungus will mutually exist with the plants around

them. Some plants even depend on these fungus species to insure their survival in the ecosystem

(Krivtsov 2004). This may be because the mycorrhizae have a unique way of sharing nutrients.

The unused nutrients from its own digestion go to the plants that they are connected too. This

nutrient store may also go on to the next plant when there is excess from another plant, so you

can see how complex this network can get. The passing around of these nutrients is another way

they are recycled within the soil (Wolfe 2001). This also helps in times of environmental stress

like drought where the plant is deprived of nutrients that would be dissolved by water. Most

people underestimate the importance of the fungus, but they are an essential part of the soil

ecosystem and the nutrient cycling.

Like the above organisms, earthworms are fantastic at breaking down different materials

and turning them into something that the plants above can use for nutrition. Eating is not their

only lucrative talent, however. They are also great at aerating the soil and transporting the

nutrients from the below ground to the above ground areas. Their burrows in the soil open up

spaces for water and nutrients to gather. Eventually plat roots will find these burrows and tap

into the wealth of health they hold (Ayres 2006). Earthworms have, for most of history, been an

indicator for healthy soil but they can also be used in speeding up the decomposition rate in your


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household compost pile. These worms procreate fast and eat most of the dead organic matter

that comes their way. They are like giants working their way through the soil particles, but this

leaves room for many other organisms to thrive

and spread out.

As the life cycle goes, earthworms also have

predators, but as mentioned before, these population

checks are always important to the ecosystems health.

In natural ecosystems like grasslands and forests, the soil settles into a specially layered

profile. It depends on where you are on the planet to determine which kind of soil you will come

across and in turn which kind of ecosystem will be growing above it. Typically, the forest soils

will have less available nutrients than the grasslands do. This is because the plant species in the

forest hold on to more of their nutrients because trees and shrubs are much larger than most

grasses. The climate above is also somewhat controlled by the plant species living there. The

Above is an example of where the different

organisms live within the soil.

www.fwcb.cfans.umn.edu
http://www.fwcb.cfans.umn.edu/http://www.fwcb.cfans.umn.edu/


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amount of carbon and oxygen in the air can be determined by how many trees and other plant

species stand in that area (Schulp 2008). In ecosystems like the tropical rain forest in Brazil, the

trees transpired large quantities of oxygen as well as water vapor and give off oxygen. All the

water vapor going into the atmosphere collects and eventually comes back down as rain. Here,

the biota plays a specific role in the recycling of fresh water. The soil also changes in these areas

as well as the organisms living within them. As you get into more extreme conditions, biota in

the soil lessens, and this is reflected in the amount of vegetation growing above. For example, in

most arid places on the earth the biota in the soil is greatly reduced from a place like the Amazon

rainforest in Brazil or the Kongo in Africa. This is further seen as most plant species are gone

from the top of the soils. The plants form little life cycles of their own which the biota thrives in,

but the biota have to be there in the first place to support the plant life. As the plant grows and

creates litter which is food for the biota and grows bigger which creates more shelter for more

organisms to come and multiply in. The less water there is in a region, however, the less likely

there is going to be much activity below the ground (Baskin 2005). For example, nematodes

need the water around the clay particles to get food and live, but when the water is scarce, they

will shut down and stop their lives until there is more water available. The longer they shut

down, the more likely they are to die completely. Therefore, in places like deserts, it is hard to

sustain a substantial amount of life under the ground let alone a forest above it (Baskin 2005).

Humans can definitely benefit from the information we learn from soil science. We see

that most of the organisms support each other and work together in order to survive the ever

changing climate. In agriculture, especially, we can try to mimic this natural environment as best

we can and allow for different organisms to live within our cultivated soils. The more diversity

we have within our fields, the better, as seen in nature. Humans can definitely have negative


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effects on the health of the ecosystems. Too much of one thing is never a good thing, as seen in

nature when populations have natural checkers and not everything can multiply exponentially.

Unfortunately, much of our agricultural practices and community building has this model of

destroying everything except for a few select things. It is important that we take a lesson from

our natural world in the way we plan cities and grow crops. We need to be more open to the

good and the bad in nature and try to live more sustainably in that way. When it comes to soil

pollution, we have seen that natural microbes will clean up our messes (Hillel 2008). But if we

abuse these organisms, they may multiply out of control or completely disappear. It is important

that we live sustainably and gather as much information about the natural environment that we

can so that we may use the information to benefit our species. That is why it is so important to

understand the soil and how the living things contained inside it react with each other and

produce living conditions for other species.


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WORKS CITED

Ayres E, Dromph KM, Bardgett RD. 2006. Do plant species encourage soil biota that specialize in the r

rapid decomposition of their litter? Soil Biology & Biochemistry38: 183-186

Baskin Y. 2005. Underground: How Creatures of Mud and Dirt Shape our World. Island Press Publishers:

Washington.

Hillel D. 2008. Soil in the Environment: Crucible of Terrestrial Life. Elsevier Inc: New York, New York.

Kristov V, Griffiths BS, Salmond R, Liddell K, Garside A, Bezginova T, Thompson JA, Staines HJ, WatlingR, Palfreyman JW. 2004. Some aspects of interrelations between fungi and other biota in

forest soil. The British Mycological Society108: 933-946

Schulp CJE, Nabuurs GJ, Verburg PH, de Waal RW. 2008. Effect of tree species on carbon stocks in forest

floor and mineral soil implications for soil carbon inventories. Forest Ecology and Management.

256: 482-490

Wolfe DW. 2001. Tales from the Underground: A Natural History of Subterranean Life. Perseus

Publishing: Cambridge, Massachusetts.

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