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Time Traveling Via Satellite
Tropical ecologist Michael Palace comes full circle with a NASA Space Archaeology grant to estimate the population of pre-Columbian Amazon indigenous peoples
MICHAEL PALACE majored in archaeology and environmental science at the University of Virginia, then turned to the environmental science side of things as he pursued his master’s degree at UVA. For his thesis he studied the dynamics of Costa Rican howler monkeys in relation to landscape-level vegetation structure. The monkeys would move about with the shifting wet/dry seasons and Palace would gather data by tagging along like an outlying member of the troop. On the side, he would often train a microphone on the howlers’ loud morning choruses, which he would later use in his semi-professional career creating electronic music blended with audio field recordings.

Ruth Varner  
Michael Palace atop an overturned tree
in the Brazilian Amazon.
Photo by Steve Hagen
Despite the inherent difficulties imposed by research in remote reaches of tropical rainforest, the jungles of Central America got into Palace’s blood. Next stop on his academic ascension was UNH where he linked up with Michael Keller, project scientist for the NASA-sponsored, Brazilian-led Large Scale Biosphere Atmosphere in Amazonia (LBA) project. Palace relished the opportunity to explore the tropical rainforests of South America and, while pursuing his Ph.D., worked full-time with Keller conducting research in three regions of the Brazilian Amazon. Among other things, he wrote computer programs and databases to visualize and statistically analyze trace gas measurements.

Abstruse scientific stuff. But Palace, now a tropical ecologist and research assistant professor at the Complex Systems Research Center (CSRC) within the Institute for the Study or Earth, Oceans, and Space, has come full circle with a $364,063 grant from NASA’s Space Archaeology Program. For the three-year project he won’t be using satellite remote sensing technology to estimate things like tree canopy dynamics or overall forest biomass. Rather, he’ll use the high-tech methods to help nail down much-disputed population estimates of pre-Columbian indigenous peoples in the Amazon Basin lowlands. The project will integrate his knowledge of remote sensing, tropical vegetation, and his interest in archaeology.

Collaborating with a Brazilian archaeologist and another ecologist on the project, Palace will use imagery from an instrument onboard NASA’s Terra satellite to locate “Amazonian black earths” or, in Portuguese, “terra preta” sites that designate areas where indigenous Amazonian peoples lived and worked the land prior to colonial contact back in the late 15th century.

“This is a big issue because people think there may be thousands of terra preta sites across the Amazonian basin,” Palace says adding, “and if we can show they are indeed that extensive it will really change our understanding of how many people lived in the region and the impact they had on what we still perceive to be ‘pristine’ forest.”

Currently, pre-Columbian population estimates vary widely - from 500,000 to 10 million - and are the subject of much controversy and debate. Knowing with more accuracy how many people might have impacted the rainforest through agriculture and development prior to European contact will help scientists understand how the Amazon Basin might withstand current pressures from deforestation, selective logging, and development.

Palace still views himself as a tropical ecologist working at the landscape level, but to study the immense Amazonian forest he has become an expert in using satellite-borne imagery. In this project he will use hyperspectral imagery taken by NASA's Hyperion sensor.

 archaeological site
Archaeological excavation of terra preta sites
in Brazil.Courtesy of Eduardo Neves.
The Hyperion camera "sees" in 220 spectral bands of light, allowing scientists to identify the chemical makeup of tree leaves, which in turn is related to nutrients in the underlying soil. The more nutrient-rich leaves or specific groups of tree species seen by Hyperion will be the signature for the Amazonian black earths Palace is looking for – sites containing soil rich in organic matter, charcoal, and nutrients and frequently associated with large accumulations of potsherds, bone, and other artifacts of human origin. The soils were created hundreds of years ago when indigenous populations slowly burned trees to make soil equivalent to "biochar," which is extremely efficient at storing carbon and nutrients and provides fertile, productive farmland.

"There are terra preta sites all over the Amazonian basin, particularly near rivers and bluffs, but no one really knows their whole distribution," says Palace, who will collaborate with Mark Bush, an ecologist from the Florida Institute of Technology, and Brazilian archaeologist Eduardo Neves of the University of San Paulo. Also collaborating on the project are Stephen Hagen, a research scientist at Applied GeoSolutions in Newmarket, N.H. who received his Ph.D. at UNH, and former CSRC faculty member Rob Braswell, now at Atmospheric Environmental Research, Inc. in Lexington, Mass.

 archaeological site
Archaeological excavation of terra preta sites in Brazil.
Courtesy of Eduardo Neves.
Having identified terra preta sites in the Hyperion imagery, the researchers will, among other methods, use a “neural network” – an adaptive mathematical system that will learn to identify the difference between sites that are terra preta and those that are not using the complex data from the Hyperion imagery. Says Palace, “Once we develop the neural network model we’ll be able to extrapolate across the entire Amazon landscape and identify the location of other sites. This will allow archaeologists to go there and determine if they are indeed terra preta and, from that, we should be able to accurately estimate the indigenous population prior to colonial contact. We will also be able to look at the connectivity and spatial dimension of these sites across the landscape and compare the location with other geological and geographic information."

At six million square kilometers, the Amazon basin contains the largest continuous rainforest in the world and constitutes 40 percent of what remains of this ecotype. If Palace's research indicates there was a large population of indigenous peoples using the forest to maintain a highly productive agricultural system, it is likely that Amazonian forest vegetation was significantly altered and may be thought of as a cultural artifact, resilient to human disturbance and not an undisturbed forest.

“The indigenous peoples probably had some sort of cycling system where they would burn fields and forests, let them grow back to a certain extent, and let mixed crops and certain types of trees grow,” Palace says. He adds that his Brazilian colleague, Eduardo Neves, has determined that three types of palm trees are prevalent in terra preta sites. “So in addition to the nutrient signature in the hyperspectral signal, we might also be seeing specific species of trees that will help us locate these areas.”

Palace will travel to Brazil to confer with his colleagues but the Amazon project will not involve any fieldwork on his part. However, a simultaneous project recently funded by the NASA New Investigator Program in Earth Science will take him back to Costa Rica where he will examine tropical forest structure using multiple remote sensing platforms, including airborne lidar.

“Lidar is a type of laser that, with the right application, can give you the shape of the whole forest from the ground to the top of the tree canopy,” Palace explains. “I’m creating a method of using lidar to understand both the forest understory and the tree canopy, which will help determine the forest structure in three dimensions.”

The same techniques used in Costa Rica can also be applied other types of habitats, including New England landscapes. Palace is doing just that as principal science investigator on a project examining Lyme disease in New Hampshire, which is funded by NASA's Experimental Program to Stimulate Competitive Research (EPSCoR) program.

The remotely sensed data includes highly detailed biophysical and biochemical information derived from satellite-based optical and radar imagery of the landscape favored by white-tailed deer and small rodents – important hosts for the tick species responsible for transmitting Lyme disease.

Back in Costa Rica, Palace will also continue work in his nonscientific endeavor of making field recordings that he uses to create “generative” electronic music under the pseudonym. “horchata.” Described as “a crafter of sonic landscapes” by one reviewer, horchata has recorded a number of albums and wrote the soundtrack to the documentary film about global warming titled "Out of Balance: ExxonMobil's Impact on Climate Change."

To hear Palace’s sound recordings visit

by David Sims, Science Writer, Institute for the Study of Earth, Oceans, and Space. Published in Summer 2010 issue of EOS Spheres.