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Sat, Feb

UNH Researchers Find Human Impact on Forest Still Evident After 500 Years

Typography

Tropical forests span a huge area, harbor a wide diversity of species, and are important to water and nutrient cycling on a planet scale. But in ancient Amazonia, over 500 years ago, clearing tropical forests was a way of survival to provide land for families to farm and villages to prosper. Researchers at the University of New Hampshire used high-tech tools to more precisely view where these cleared sites were and how much lasting impact they had on the rainforest in the Amazon Basin in South America.

Tropical forests span a huge area, harbor a wide diversity of species, and are important to water and nutrient cycling on a planet scale. But in ancient Amazonia, over 500 years ago, clearing tropical forests was a way of survival to provide land for families to farm and villages to prosper. Researchers at the University of New Hampshire used high-tech tools to more precisely view where these cleared sites were and how much lasting impact they had on the rainforest in the Amazon Basin in South America.

“One of the key mysteries in this area of the world is that no one knows how many people lived in Amazonia before European contact,” said Michael Palace, an associate professor in the Earth Sciences Department and Earth Systems Research Center at UNH. “Once the Europeans arrived, indigenous populations were devastated due to disease, slavery and displacement so it’s often hard to determine lasting impact. It is important to understand the resilience or fragility of these forests to past human disturbance, which allows for appropriate planning on the use of natural resources.”

One of the few indicators of human settlements are the terra preta, or Amazonian Dark Earths (ADEs). These are black, human-made soils that are enriched by materials left behind from past societies, pottery remnants, charcoal and other artifacts frequently associated with human origin. There is very little rock and metal in that part of the world (a former ocean bottom), and wood, bone and other organic materials decay quickly in the humid tropics.

In their study, recently published in the journal Ecosphere, the researchers used imagery from NASA’s terra satellite, MODIS, and geospatial modeling to predict the ADE probability across six million square kilometers of the Amazonia. They found that biomass (primarily weight of trees in forests), tree height, and tree cover were all lower at ADE sites than adjacent random non-ADE locations. The ADE sites were also more susceptible to drought.

Read more at University of New Hampshire

Image: Map developed using satellite imagery and spatial modeling showing estimated past human impact on the Amazonian forest. (Credit: Michael Palace/UNH)