Forests, fields, and the edge of sustainability at the ancient Maya city of Tikal

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 111; no. 52; pp. 18513 - 18518
• Main Authors: Lentz, David L., Dunning, Nicholas P., Scarborough, Vernon L., Magee, Kevin S., Thompson, Kim M., Weaver, Eric, Carr, Christopher, Terry, Richard E., Islebe, Gerald, Tankersley, Kenneth B., Sierra, Liwy Grazioso, Jones, John G., Buttles, Palma, Valdez, Fred, Hernandez, Carmen E. Ramos
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 30-12-2014; National Acad Sciences
• Subjects: Agriculture; Agroforestry; Cacao; Civilization; Corn; Fallowing; Forest cover; Forests; History, Ancient; History, Medieval; Humans; Hydraulics; Intensive production; Isotopes; Lowlands; Mayan civilization; Mexico; Montane forests; Paleobotany; Paleoecology; Plants; Social Sciences; Sustainable agriculture; Urban Renewal - history; Mexico; irrigation; paleoecology; paleoethnobotany; Neotropics; root crops
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1408631111

Tikal has long been viewed as one of the leading polities of the ancient Maya realm, yet how the city was able to maintain its substantial population in the midst of a tropical forest environment has been a topic of unresolved debate among researchers for decades. We present ecological, paleoethnobotanical, hydraulic, remote sensing, edaphic, and isotopic evidence that reveals how the Late Classic Maya at Tikal practiced intensive forms of agriculture (including irrigation, terrace construction, arboriculture, household gardens, and short fallow swidden) coupled with carefully controlled agroforestry and a complex system of water retention and redistribution. Empirical evidence is presented to demonstrate that this assiduously managed anthropogenic ecosystem of the Classic period Maya was a landscape optimized in a way that provided sustenance to a relatively large population in a preindustrial, low-density urban community. This landscape productivity optimization, however, came with a heavy cost of reduced environmental resiliency and a complete reliance on consistent annual rainfall. Recent speleothem data collected from regional caves showed that persistent episodes of unusually low rainfall were prevalent in the mid-9th century A.D., a time period that coincides strikingly with the abandonment of Tikal and the erection of its last dated monument in A.D. 869. The intensified resource management strategy used at Tikal—already operating at the landscape’s carrying capacity—ceased to provide adequate food, fuel, and drinking water for the Late Classic populace in the face of extended periods of drought. As a result, social disorder and abandonment ensued.
Significance The rise of complex societies and sustainable land use associated with urban centers has been a major focus for anthropologists, geographers, and ecologists. Here we present a quantitative assessment of the agricultural, agroforestry, and water management strategies of the inhabitants of the prominent ancient Maya city of Tikal, and how their land use practices effectively sustained a low-density urban population for many centuries. Our findings also reveal, however, that the productive landscape surrounding Tikal, managed to the brink of its carrying capacity during the Late Classic period, did not have the resilience to withstand the droughts of the 9th century. These results offer essential insights that address the question of why some cities thrive while others decline.