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Ancient trash heaps gave rise to Everglades tree islands
American Geophysical Union ^ | March 21, 2011 | Unknown

Posted on 03/21/2011 9:35:06 AM PDT by decimon

SANTA FE, N.M. – Garbage mounds left by prehistoric humans might have driven the formation of many of the Florida Everglades' tree islands, distinctive havens of exceptional ecological richness in the sprawling marsh that are today threatened by human development.

Tree islands are patches of relatively high and dry ground that dot the marshes of the Everglades. Typically a meter (3.3 feet) or so high, many of them are elevated enough to allow trees to grow. They provide a nesting site for alligators and a refuge for birds, panthers, and other wildlife.

Scientists have thought for many years that the so-called fixed tree islands (a larger type of tree island frequently found in the Everglades' main channel, Shark River Slough) developed on protrusions from the rocky layer of a mineral called carbonate that sits beneath the marsh. Now, new research indicates that the real trigger for island development might have been middens, or trash piles left behind from human settlements that date to about 5,000 years ago.

These middens, a mixture of bones, food discards, charcoal, and human artifacts (such as clay pots and shell tools), would have provided an elevated area, drier than the surrounding marsh, allowing trees and other vegetation to grow. Bones also leaked phosphorus, a nutrient for plants that is otherwise scarce in the Everglades.

"This goes to show that human disturbance in the environment doesn't always have a negative consequence," says Gail Chmura, a paleoecologist at McGill University in Montreal, Canada, and one of the authors of the study.

Chmura will be presenting her research tomorrow, Tuesday 22 March, at the American Geophysical Union's Chapman Conference on Climates, Past Landscapes, and Civilizations. About 95 scientists have converged on Santa Fe this week to discuss the latest research findings from archeology, paleoclimatology, paleoecology, and other fields that reveal how changes in regional and global climate have impacted the development and fates of societies.

In a previous scientific investigation of tree islands, Margo Schwadron, an archeologist with the National Park Service, cut through the elevated bedrock at the base of two islands and discovered that it was actually a so-called "perched carbonate layer," because there was more soil and a midden below. Later, a team including Chmura's graduate student Maria-Theresia Graf performed additional excavations in South Florida and found more of the perched carbonate layers.

Chemical analysis of samples of these curious perched layers revealed that they are made up partially of carbonates that had dissolved from the bedrock below, Chmura says. The layer also contains phosphorus from dissolved bones, she adds. Her team concluded that trees are key to the formation of this layer: During South Florida's dry season, their roots draw in large quantities of ground water but allow the phosphates and carbonates dissolved in it to seep out and coalesce into the stone-like layer.

The perched carbonate plays a key role in letting tree islands rebound after fires: because it does not burn, it protects the underlying soil, and it maintains the islands' elevation, allowing vegetation to regrow after the fire. Humans are now threatening the existence of tree islands, by cutting down trees (whose roots keep the perched layer in place) and artificially maintaining high water levels year-round in some water control systems, which could cause the layer to dissolve.

Chmura's team now wants to explore exactly when trees started growing on the tree islands.

###

Notes for Journalists

This research by Chmura et al. is being presented on Tuesday, 22 March, at the American Geophysical Union's Chapman Conference on Climates, Past Landscapes, and Civilizations.

To read the abstract of this presentation, please use this search engine: http://agu-cc11cp.abstractcentral.com/itin.jsp

Click on Search, type Chmura in the Author/Presenter field and click on the orange Search button at the bottom.

Neither the abstract nor this press release are under embargo.

Contact information for the author: Gail L. Chmura, Telephone: +1 (514)926-6854, Email: gail.chmura@mcgill.ca


TOPICS: History
KEYWORDS: godsgravesglyphs
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To: Frantzie
You're right about those melaleucca trees. We planted one behind our house when I was a kid, where the washer dumped its water, and it thrived in that soapy, bleachy water. Years later, I tried to cut it down and found out how hard that wood is below the paper bark. The brazillian pepper trees are just as bad...

Mike

21 posted on 03/21/2011 10:58:18 AM PDT by MichaelP (The ultimate result of shielding men from the effects of folly is to fill the world with fools ~HS)
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To: Frantzie

“Idiots planted they to try to drain the everglades.”

How about:
“Government idiots planted them to try to drain the Everglades.”

The aerial seeding of the Everglades with Australian Melaleuuca tree seed WAS a gooberment project.

Typical of Gooberment AgencyPersons, there was a monument to that project in the city of Davie, Fl.

Long gone, vanished into the black hole of revisionist history.


22 posted on 03/21/2011 11:10:38 AM PDT by GladesGuru (In a society predicated upon freedom, it is essential to examine principles,)
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To: decimon

I’m skeptical of this explanation. There’s so many ‘heads’ that I can’t imagine ancient human garbage accounting for them.
The phosphorus could have come from the huge phosphate mines N. W. of Lake Okeechobee and been carried in the aquifer.


23 posted on 03/21/2011 11:49:57 AM PDT by Vinnie
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To: Migraine

I say we evacuate the site and nuke it from orbit. It’s the only way to be sure.

Seriously, if this is true, isn’t an EPA superfund cleanup site warranted?

/sarc


24 posted on 03/21/2011 12:54:06 PM PDT by Secret Agent Man (I'd like to tell you, but then I'd have to kill you.)
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To: The Iceman Cometh

Thanks for not mentioning “ancient” and “mound” together in the same sentence.


25 posted on 03/21/2011 12:55:26 PM PDT by Secret Agent Man (I'd like to tell you, but then I'd have to kill you.)
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To: decimon

“...This goes to show that human disturbance in the environment doesn’t always have a negative consequence...”
-
Stupid statement.


26 posted on 03/21/2011 5:05:32 PM PDT by Repeal The 17th
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To: denydenydeny
Actualllllyyyy... what happened is that ancient man discovered the huge content of phosphorous in the human feces.

So these mounds, especially there size & proliferation, is the direct result of a concerted effort by our forefathers to crap there way out of the muck & mire of their lives.

27 posted on 03/22/2011 5:37:18 AM PDT by GogogoStopSTOP
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To: GladesGuru

They did the same thing with Australian pines in Palm Beach County. Now the taxpayers are paying to have those removed.


28 posted on 03/22/2011 5:41:33 AM PDT by liberalh8ter
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To: decimon

Typically, archeologists capture the field and then occupy the language.

Tree Island = Hummock

The thesis is that the hummocks were where humans lived and left trash


29 posted on 03/22/2011 5:44:57 AM PDT by bert (K.E. N.P. N.C. D.E. +12 ....( History is a process, not an event ))
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To: decimon; StayAt HomeMother; Ernest_at_the_Beach; 1010RD; 21twelve; 24Karet; 2ndDivisionVet; ...

· GGG managers are SunkenCiv, StayAt HomeMother, and Ernest_at_the_Beach ·
· join list or digest · view topics · view or post blog · bookmark · post a topic · subscribe ·

 
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Thanks decimon.

To all -- please ping me to other topics which are appropriate for the GGG list.
 

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· Science topic · science keyword · Books/Literature topic · pages keyword ·


30 posted on 03/22/2011 5:32:28 PM PDT by SunkenCiv (The 2nd Amendment follows right behind the 1st because some people are hard of hearing.)
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To: Migraine

No...this just shows us that trees, like humans, are NOT part of nature.
;-)


31 posted on 03/22/2011 6:03:10 PM PDT by bannie (( boom ))
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To: decimon

These trash heap middens go all the way north up the Everglades tributaries up towards Orlando FL and Shingle Creek. From Northeast of there they are shown again in the St John’s tributaries heading north toward the FL/GA border.

http://www.volusia.org/history/sitemap.jpg

I’ve visited afew of these places, beautiful spots, but I can’t believe the mosquitos didn’t cause endemic tropical diseases in the native population.


32 posted on 03/22/2011 8:27:17 PM PDT by JerseyHighlander
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To: decimon
These middens, a mixture of bones, food discards, charcoal, and human artifacts (such as clay pots and shell tools), would have provided an elevated area, drier than the surrounding marsh, allowing trees and other vegetation to grow. Bones also leaked phosphorus, a nutrient for plants that is otherwise scarce in the Everglades.

Most nutrients are scarce in the Everglades. It's like a desert with water. I don't know why people get all misty eyed about it.

33 posted on 03/22/2011 8:41:35 PM PDT by Moonman62 (Half of all Americans are above average. Politicians come from the other half.)
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To: decimon
Notes for reporters: ...distinctive havens of exceptional ecological richness in the sprawling marsh that are today threatened by human development...

That's their money quote.

34 posted on 03/23/2011 8:02:51 AM PDT by 1010RD (First, Do No Harm)
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