Ancient Maya activities left lasting impact on environment

Maya activity more than 2,000 years ago not only contributed to the decline of their environment but continues to influence today's environmental conditions, researchers have found.
Synthesising old and new data, researchers have for the first time shown the full extent of the "Mayacene" as a microcosm of the early anthropocene - a period when human activity began greatly affecting environmental conditions.
"Most popular sources talk about the anthropocene and human impacts on climate since the industrial revolution, but we are looking at a deeper history," said lead author Tim Beach, professor at University of Texas at Austin.
"Though it has no doubt accelerated in the last century, humans' impact on the environment has been going on a lot longer," Beach said.

By looking at Maya impacts on climate, vegetation, hydrology and lithosphere from 3,000 to 1,000 years ago, researchers proposed that the Maya's advanced urban and rural infrastructure altered ecosystems within globally important tropical forests.
The researchers studying the tropical lowlands of Central America identified six stratigraphic markers - or "golden spikes" - that indicate a time of large-scale change, including "Maya clay" rocks, unique soil sequences, carbon isotope ratios, widespread chemical enrichment, building remains and landscape modifications, and signs of Maya-induced climate change.

"These spikes give us insight into how and why Mayas interacted with their environment, as well as the scope of their activity," said co-author Sheryl Luzzadder-Beach, chair of the Department of Geography and the Environment at University of Texas.

Maya clay and soil sequences indicated erosion, human land-use changes and periods of instability.
Soil profiles near wetlands revealed heightened carbon isotope ratios due to agriculture and corn production; and researchers noted a three to fourfold increase in phosphorus throughout Maya-age sediments.
The most visual indication of human impact was found in building material remains and landscape modifications.
Researchers believe that these clues show how the Maya used water management to adapt to climate change.
"In studying the wetland systems, we were surprised to find a combination of human and natural contributions," Luzzadder-Beach said.
"Geochemical changes indicated that some wetlands were natural, while others were built landscapes used to grow crops away from the large population," Luzzadder-Beach said.

While some studies suggest that deforestation and other land use contributed to warming and drying of the regional climate by the Classic Period (1,700-1,100 years ago), many existing forests are still influenced by Maya activities, with many structures, terraces and wetlands still existing today, researchers said.
The study will be published in the Quaternary Science Reviews.