deltaH
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Namibian 'fairy circles'
Utterly bizarre natural mystery... the barren circles of Namibia:
http://www.bbc.com/earth/story/20140916-mystery-fairy-circle...
Thoughts?
PS
You gotta love
"...Cowan jokes that each scientist sees the solution in terms of their own particular area of expertise: the insect biologists think the circles are
created by ants or termites, the plant physiologists think it’s grasses, and the chemists think it’s gases. Cowan, a microbial ecologist, proves
no exception..."
AMEN
[Edited on 17-9-2014 by deltaH]
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Artemus Gordon
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"...Cowan jokes that each scientist sees the solution in terms of their own particular area of expertise: the insect biologists think the circles are
created by ants or termites, the plant physiologists think it’s grasses, and the chemists think it’s gases. Cowan, a microbial ecologist, proves
no exception..."
Like the old saying: When you have a brand-new hammer, every problem you see looks like a protruding nail head. 
I don't like the termite theory because I would expect a termite colony to grow by extending "arms" in various directions, not by extending the radius
of a near-perfect circle.
I would think the competing-grasses theory could be tested by adding water and fertilizer to a few of the circles, or perhaps to one half of each of a
few circles to see if the circle shape could be altered.
The fungus explanation is my favorite because it is the explanation for fairy circles in lawns here in North America, which also exhibit the
near-perfect circularity, little or no grass growth in the center, and lush grass growth at the perimeter.
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deltaH
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Conditions are damn arid for such an extensive fungal growth, if that. Also, why the regular spacing between the rings then? Darn peculiar 
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TheChemiKid
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This is crazy, maybe some witty people are behind this.
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Amos
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Perhaps a single fungal organism? If it spread underground and developed at regular intervals to create such hot spots, it could effectively prevent
grasses from rooting, but the increased soil nutrition it would create would help grass on the periphery grow taller.
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froot
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My theory:
The regular spacing rules out plants and fungi in my opinion, unless chemical communication is involved. The spacing is consistent with the
territorial nature of fauna, in this case, small fauna. Take fossorial reptiles for example, hypothetically something like a legless lizard (Acontias
sp. for expample) that 'swims' in soft sand could be keeping it's territory free of vegetation for security, mobility and breeding reasons. Competing
males would keep maximum distance from each other hence the regular spacing we see from above. This type of reptile is incredibly difficult to find
even if it's right there below your feet. The grass around the perimeters is larger simply because it gets to enjoy the extra rainwater that filters
from the bare circular patches.
We salute the improvement of the human genome by honoring those who remove themselves from it.
Of necessity, this honor is generally bestowed posthumously. - www.darwinawards.com |
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Praxichys
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Oh, sorry guys. I was testing my orbital death ray. I didn't think anyone would mind.
As for "...Cowan jokes that each scientist sees the solution in terms of their own particular area of expertise: the insect biologists think the
circles are created by ants or termites, the plant physiologists think it’s grasses, and the chemists think it’s gases. Cowan, a microbial
ecologist, proves no exception..."
Well, sure. You wouldn't want someone unqualified in entomology disproving the termite theory, for instance. Each type of scientist is simply looking
for what he is best skilled to look for. The beauty of science is that eventually somebody will be right, and that will be the accepted theory among
all scientists, regardless of the discipline.
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deltaH
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Interesting, but the article states that the plants would not grow in soil samples either, so for the fauna hypothesis to work, it means that any
fauna must have some lingering herbicidal effect.
I think the reason this has baffled the scientists is because as Cowen joked, each investigator is seeing it through their lens of specialisation when
in fact, the whole picture may be a combination of effects across specialisations.
For example, here is one thumb-sucked hypothesis of mine that demonstrates what I mean:
Being a desert, the soil there is probably exceptionally barren, which means that those grasses must have adapted to growing in very nutrient poor
soil. Such plant types can be sensitive to over fertilisation, for example, the protea family of plants must grow in very barren soil, adding even
small amounts of fertiliser kills them because they are so well adapted to thrive where there is almost no nutrients.
Now that said, I agree with froot that the spacing and shape and size points to fauna territorialism. It is possible that whatever
fauna is causing this, prevents those plants from growing in it because the soil temporarily becomes too nutrient rich for the plants, perhaps by the
animals excrement. Remember, it hardly rains here, so inorganic salts may build up to levels toxic where they might not in other places (it was
mentioned that the circles are more pronounced in the more arid parts). At some point on the fringe of the territory, the micronutrient levels are
high but not too high to prevent those grasses from growing, hence at this boundary, they flourish as if fertilised (but not toxically so).
This hypothesis could be tested by comparing soil analysis of macro and micro [plant] nutrient elements from samples in and outside the circles.
Then if the trend holds, then the cause for these nutrients can be hunted. The presence of termites were already mentioned. Even if they move on, they
may leave the area inorganically poisoned until it rains.
[Edited on 18-9-2014 by deltaH]
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aga
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The noticeably thicker growth of the plants at the edge of the circles is a big clue.
It's a plant thing.
" says .. Walter Tschinkel ... They are like little satellite dishes.”
Likely morning dew collects there in significant (relatively) volume, which the plants around the edge rapidly suck dry before the sun rises,
preventing anything else growing.
The bottom photos shows some invasion of the inner part of the circle.
Either it's in the pre-kill-everything-inside phase, or some plants have adapted to soak up water faster than the killers around the edge, in which
case they will eventually kill off the plants around the edge, and over time the circle will move.
Simples: all it took was a Generalist rater than a Specialist.
Now a Specialist can Generally prove the theory wrong.
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