American Prairie and Amazon Forest: Man Made ?

A very interesting theory from an article in 2002.  American Prairie and Amazon forest have been shaped by humans over thousands of years, and are not pristine environments as previously thought.  The Native Americans burned the Prairie Grasses to create a habitat ideal for bison, elk and deer; i.e. a gigantic farm for meat.  In the Amazon Forest, Amazonians created large tracts of very fertile super soil (Terra Preta wiki) in an infertile area.

The initial evidence for Prairie burning was as follows.

• de Soto's travels thru South East US in 1539 did not see bison.
• Archaeology of settlements shows very little bison/elk bones 
• Disease brought in by Soto and crowd (and pigs) kills off the Native Americans.
• 100 years later French explorers in the South East US saw no traces of man instead huge herds of bison
• Conclusion: Native Americans kept bison population down. After Native Americans died of European diseases the bison numbers exploded.

Anyway excerpts article.

Every tomato in Italy, every potato in Ireland, and every hot pepper in Thailand came from this hemisphere. Worldwide, more than half the crops grown today were initially developed in the Americas.

The Aztec capital of Tenochtitlán dazzled Hernán Cortés in 1519; it was bigger than Paris, Europe's greatest metropolis. The Spaniards gawped like hayseeds at the wide streets, ornately carved buildings, and markets bright with goods from hundreds of miles away. They had never before seen a city with botanical gardens, for the excellent reason that none existed in Europe. The same novelty attended the force of a thousand men that kept the crowded streets immaculate. (Streets that weren't ankle-deep in sewage! The conquistadors had never heard of such a thing.)

The Hurons, a chagrined missionary reported, thought the French possessed "little intelligence in comparison to themselves." Europeans, Indians said, were physically weak, sexually untrustworthy, atrociously ugly, and just plain dirty. (Spaniards, who seldom if ever bathed, were amazed by the Aztec desire for personal cleanliness.)
Rather than domesticating animals for meat, Indians retooled whole ecosystems to grow bumper crops of elk, deer, and bison. The first white settlers in Ohio found forests as open as English parks—they could drive carriages through the woods.

In North America, Indian torches had their biggest impact on the Midwestern prairie, much or most of which was created and maintained by fire. Millennia of exuberant burning shaped the plains into vast buffalo farms. When Indian societies disintegrated, forest invaded savannah in Wisconsin, Illinois, Kansas, Nebraska, and the Texas Hill Country.

Yet recently a growing number of researchers have come to believe that Indian societies had an enormous environmental impact on the jungle. Indeed, some anthropologists have called the Amazon forest itself a cultural artifact—that is, an artificial object.

In a widely cited article from 1989, William Balée, the Tulane anthropologist, cautiously estimated that about 12 percent of the nonflooded Amazon forest was of anthropogenic origin—directly or indirectly created by human beings. In some circles this is now seen as a conservative position. "I basically think it's all human-created," Clement told me in Brazil. He argues that Indians changed the assortment and density of species throughout the region.

Update

Strange Forest Patches Littering The Amazon Point to Agriculture 10,000 Years Ago
Now, thanks to new analysis of the sediment found in some of these islands, researchers have unearthed signs that these spots were used to grow cassava (manioc) and squash a little over 10,000 years ago.
That's impressive, as this timing places them some 8,000 years earlier than scientists had previously found evidence for, indicating that the people who lived in this part of the world - the southwestern corner of the Amazon basin - got a head start on farming practices.


https://www.sciencealert.com/the-amazon-basin-was-an-ancient-agricultural-hotspot-10-000-year-old-evidence-says

References

http://www.theatlantic.com/magazine/archive/2002/03/1491/302445/
http://www.instructables.com/id/Make-your-own-BioChar-and-Terra-Preta/?ALLSTEPS
http://news.nationalgeographic.com/news/2008/11/081119-lost-cities-amazon.html 
http://www.fws.gov/refuge/Neal_Smith/wildlife_and_habitat/tallgrass_prairie.html
http://news.nationalgeographic.com/news/2008/11/081119-lost-cities-amazon.html

This is the Knox of N. America.  La relación of Álvar Núñez Cabeza de Vaca (1528-15386)
https://ia800504.us.archive.org/15/items/journeyofalvarnu00n/journeyofalvarnu00n.pdf