麻豆淫院

The inhabitants of the "Lost City of the Amazon" in Ecuador's Upano River Valley grew corn and planted alder trees for over 1,200 years, but a later occupation that lasted just 300 years was the one that changed the ecology of the forest.

A new study led by professor Mark Bush at Florida Institute of Technology and professor Crystal McMichael at the University of Amsterdam used microfossils extracted from the sediment of Lake Cormor谩n to provide the first detailed, 2,700-years-long view of changing landscapes in the Upano River Valley.

The paper, "Ecological Legacies and Recent Footprints of the Amazon's Lost City," is today in Nature Communications.

Their work builds on existing archaeological studies that documented over 7,000 structures hidden by the forests of the Upano Valley that have been described by some researchers as the Lost City of the Amazon.

"Our study provides an improved timeline of human activity in the valley, as we see people moving in and out of the landscape and different styles of cultivation coming and going," said Bush, who leads the Institute for Global Ecology at Florida Tech.

About 750 B.C., the Upano civilization started their occupation of the valley. By about A.D. 250, their influence on the area began to weaken before disappearing about A.D. 550. The authors refute an existing idea that a large ashfall from the Sangay volcano caused the abandonment, instead finding that it was a gradual decline over several hundred years.

After the abandonment, the forest closed over traces of human presence until a new wave of occupants arrived about A.D. 1500. These people farmed corn until they too abandoned the land about A.D. 1800. The forest that recovered after that abandonment was rich in tall palms, creating a forest type that had not been seen in the prior millennia.

The authors conclude that a blend of climate change and human impacts has shaped the modern forests of the Upano River Valley and that though the forests appear natural, they have only existed in their modern form for about 200 years.

"This work highlights the importance of looking into the past to understand the present," said co-author McMichael.

The modern forests around Lake Cormor谩n are protected by the Sangay National Park.