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.
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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
All-American trash ping.
So. Sometimes, when humans leave their foul footprints, good things happen? How can this be????
Some people are apparently born without the irony gene.
These were the pure humans that lived with nature, not the evil white man that destroys nature.
Thousands of square miles of sawgrass is what the author terms ecological richness. If you really want the area to have ecological richness, drain the fetid swamp dry.
Rocket scientists avoid this line of work: where would YOU sit to have a meal or light a fire to cook with? In the water or on a small mount. Set a pot down on the low land or on a mound?
Maybe they should rephrase it: First American BBQ Grills
I think they need to dig a foot deeper.
Shell mounds re-invented.
“The layer also contains phosphorus from dissolved bones,”
If you were an animal dying in the swamp wouldn’t you climb up out of the water to find a more comfortable place to expire?
“Rocket scientists avoid this line of work: where would YOU sit to have a meal or light a fire to cook with? In the water or on a small mount. “
The same is true for the ag. fields here in NC. Look for the sandy ridges and that’s where you’ll find the arrowheads and pot shards. If you’re barefoot where would you rather camp, in the wet sand or wet clay?
Fixed it.
Bad idea. The Everglades provides S FL with most of it’s water. No need to build between Miami and Naples. FL has 10 years of housing inventory anyway and too many people.
Not one word mentioned about the melaleuuca trees. They suck up all the water and are a pest taking over thousands of acres. Idiots planted they to try to drain the everglades.
Yep. You know, the kind that used to stampede entire herds of buffalo over a cliff; and others that completely clear-cut Easter Island.
Seriously, though -- God has made the earth so ingeniously that, if we practice sensible husbandry and cultivation, and clean up after ourselves, the environment actually improves. But if we rape the environment, the environment knows how to screw us back.
So, I suppose this explains why the regulators took all the phosphorus out of dishwasher soap, with the result that many of our dishwashers broke over the course of the past year.
We wouldn't want to be leaking a "nutrient for plants" into our streams and ponds, would we?
Talk like that is going to lose her some big Gubmint grants!
I never said anything about housing. There is about as little bio-diversity in the everglades as there is in a densely planted commercial pine plantation, or melaleuuca stand.
If you want increased panther habitat, drain the area and in a few years the panther range will be greatly increased.
You have a point about the Biscayne aquifer. If the deeper Floridan aquifer isn't for some reason suitable for use, perhaps some portion of normal sheetflow from Okeechobee to the southeast can be preserved. Otherwise, draw surface water and purify via reverse osmosis as is done in many municipalities across the nation.
Another Florida amusement park. Probably $50 to get in to see it.
No kidding. Words fail me.
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