Mexico City

Caroline Craddock (MLA I ‘21)

Mexico City, built upon lakes, is now experiencing subsidence as it pumps more and more water from the ground in response to rapid urbanization. The Mezquital, once an arid valley, is now wet, as Mexico City deposits its wastewater there. Two feats of human intervention have drastically changed Mexico’s landscapes. What can we learn from how these landscapes once were, and their histories of human intervention?

The Aztecs built their capital city of Tenochtitlan on a network of lake beds in the basin of Mexico. A 7.4 mile long canal, today called the Canal Nacional, connected Tenochtitlan to the lake of Xochimilco, where much of the food consumed by the 200,000 inhabitants of Tenochtitlan from the 14th to 16th centuries AD was grown. Xochimilco consisted of a lake filled with artificial islands called chinampas that were used for agriculture. Today, parts of Lake Xochimilco still consist of canals and chinampas, providing contemporary viewers a living image of the unique chinampa agriculture practices of the people of Xochimilco. Unfortunately, a number of factors caused by the urbanization of Mexico City have threatened the preservation of the chinampas.

The indigenous people of Xochimilco created the chinampas by piling lake mud onto reed mats until they sunk to the bottom of the lake. Repeating this process until a small island was formed, they then anchored the chinampas into the ground by planting ahuejote, or Salix bomplandiana, trees, along their edges. This tree was essential to the formation of the chinampas as its extensive and compact root system could be in contact with water without rotting, maintaining the soil of the chinampas intact and keeping it from eroding. In addition, the ahuejote benefitted the crops being grown on the chinampas. The ahuejote trunks, when planted one next to the other, acted as a curtain to protect the crops from wind, while the sparse foliage of the tree allowed just the right amount of sun to shine on the crops.

Maize, beans, squash, chiles, potatoes, and flowers were common crops grown at Xochimilco. Chinampa agriculture was highly productive, with 10,000 hectares of chinampas providing the “basic food needs” of 500,000 people. Likewise, native aquatic creatures such as the axolotl (Ambystoma mexicanum), a one-foot long salamander, and the acocil (Cambarellus montezumae), a type of crayfish, lived in the canals and were a common part of the Aztec diet. 

Unfortunately, the effects of urbanization in Mexico City, one of the largest and most populated cities in the world, and its lack of appropriate hydraulic infrastructure have negatively affected Xochimilco and its chinampa agriculture. For example, the canals of Xochimilco are losing water due to urbanization. In 1913 the construction of an aqueduct between two riverbeds in Xochimilco led to the diminishing of water levels in the canals. In addition, due to the rise in population, the City of Mexico has turned to the wells underneath Xochimilco as sources of drinking water. Not only do the canals experience diminishing water levels, but they also suffer from major flooding, as stormwater runoff, due to increased urbanization, has nowhere to seep into except for the canals. Lastly, due to pollution, the surface water of Xochimilco has been contaminated and the ahuejote trees negatively affected. Lastly, wastewater treatment facilities, the lake’s only water source, have caused the fish living in the canals to be filled with heavy metals.

Anthony Depalma, “Mexico City Restoring Area Tilled by Aztecs,”
The New YorkTimes, September 14, 1993, sec. Science, http://www.nytimes.com/1993/09/14/science/mexico-city-restoring-area-tilled-by-aztecs.html.

John Beardsley, Mario Schjetnan: Landscape, Architecture, and Urbanism (Washington, DC: Spacemaker Press, 2007), 14.
Yair Merlín-Uribe et al., “Environmental and Socio-Economic Sustainability of Chinampas (Raised Beds) in Xochimilco, Mexico City,” 228.
Beardsley, Mario Schjetnan: Landscape, Architecture, and Urbanism, 39.
Patronato del Parque Ecológico de Xochimilco, ed., El Ahuejote (Xochimilco, DF: Distribuido por la Unión de Voceadores de México, 1993).
Pablo Torres-Lima, Beatriz Canabal-Cristiani, and Gilberto Burela-Rueda, “Urban Sustainable Agriculture: The Paradox of the Chinampa System in Mexico City,” 39.
“Axolotl | National Geographic.” Accessed April 16, 2020. https://www.nationalgeographic.com/animals/amphibians/a/axolotl/.
Staller, John, and Michael Carrasco. Pre-Columbian Foodways: Interdisciplinary Approaches to Food, Culture, and Markets in Ancient Mesoamerica. Springer Science & Business Media, 2009.
Erwin Stephan-Otto, “Xochimilco Ecological Park: A Replicateable Model,” Political and Social Sciences Faculty of the National Autonomous University of Mexico, http://www.pex.org.mx/docs/Replicable%20INgles.pdf, 5.
Miquel Adrià et al., eds., Mario Schjetnan: Entorno urbano y paisaje = Urban envrironment and landscape (México, D.F: Arquine, 2012).
Erwin Stephan-Otto, “Xochimilco Ecological Park: A Replicateable Model”, 8.
Beardsley, Mario Schjetnan: Landscape, Architecture, and Urbanism, 40.

Mezquital

Emma Mendel (MDes ULE ‘21)

The Mezquital Valley is composed of small valleys and flat areas located in the western part of the state of Hidalgo, north of Mexico City. It reaches altitudes between 1,700 metres (5,600 ft) and 2,100 metres (6,900 ft) above sea level. It is part of the Trans-Mexican Volcanic Belt and is one of Mexico’s main semi-arid regions. Before the arrival of the Spanish, the population that shaped the arid region were composed of Otomi people. As told by native groups, Otomi people migrated after the fall of Tula, which was the main city of the Toltecs in the west. By the thirteenth century, they formed a powerful community that made up the Otomi people in the north of the Valley of Mexico. However during the fourteenth century, their power declined due to wars between the Cuautitlan and the Mexica in the Valley of Mexico. As a result, the Otomi people dispersed north and east, where they remain the dominant indigenous population up to present day. By the time European settlers entered into the Mezquital Valley, the area had transformed into a fertile, densely populated agricultural mosaic, composed of croplands, irrigation canals and terraces.

On a larger scale the agricultural production in these provinces concentrated around classic Mesoamerican crops such as maize, beans, and squash, together with chilies, tomatoes, beans, amaranth, sage, and others. In Mezquital, variations in crops depended on the local native plant species that were grounded in the microclimate and the absence of water for irrigation. As accounted in court by indigenous peoples from the Mezquital Valley, “irrigation was necessary to secure harvests in this semiarid region.” Evidence can be found by archeological sites that the Tula region and northern end of Mexico Valley, required extensive irrigation systems to collect the infrequent rainfall or frost. As an effect of the arid environment, dry red clay soils, in the form of vertisols, evolve as an ideal host for Crassulacean Acid Metabolism plants. Crassulacean Acid Metabolism, also known as CAM photosynthesis, is a carbon fixation mechanism that evolved out of some plants in order to adapt dry or arid conditions. The mechanism of this can be understood through this video: CAM plants (video) | Photosynthesis

C3 photosynthesis produces a three-carbon compound via the Calvin cycle. This allows for 1 PGAL to be used for carbohydrates in the plant. Plants can also fix oxygen but makes them much less efficient since there is no PGAL generated and therefore no carbohydrates can be produced. All of this happens in the Mesophyll layer.Fascinatingly, for C4 photosynthesis an intermediate four-carbon compound that splits into a three-carbon compound for the Calvin cycle is done in the Mesophyll and Bundle Shealth layer. Essentially, separating the calvin cycle deeper within the leaf so no oxygen can get to it. Plants that use CAM photosynthesis gather sunlight during the day and fix carbon dioxide molecules at night.

Culturally for the Otomi society, crops such as the maguey plant played critical roles in the ritualization and spiritual relationships the Otomis had with their deities. For example, the pulque harvested from the maguey plant was used as an offering to the goddess of maguey, Mayahuel. Macuil-Tochtli or Five Rabbit and Ometochtli or Two Rabbit, were both part of the pantheon of Centzon Totochtin, the four hundred rabbit gods of drunkenness. For the Aztecs, pulque was rated by its  intoxication on a scale of one to 400 rabbits. “In Aztec ritual life, celebrants were permitted to drink alcohol during certain feasting events governed by the calendars, but even then quantities were limited and taken under clearly prescribed conditions,” DiCesare says. “You could only have four bowls of pulque; if you had a fifth it was excessive.” In the Codex Borgia, Tlalogue is extensively represented as watering maize fields with five versions of the Tlaloque, each relating to different rainfalls and drought cycles. On page 28 of the Codex Borgia, the Five Tlalogue are pictured watering maize fields. Each Tlaloc is pictured watering the maize with differing types of rains, of which only one was beneficial. The other forms of rain were depicted as destroyers of crops, “fiery rain, fungus rain, wind rain, and flint blade rain”. This depiction shows the power that Tlaloc had over the Central American crop supply. But it also speaks to the high ratio of damaging rains to beneficial rains. In such depictions the symbol of rain is shown in the axonometric above. The soils of Mezquital encapsulate oral traditions, memories attached to the cosmos traced in the soils of the Mezquital Valley. As such, the Otomi people’s relation to their land exists in the cultural production of an immortal soil.

Consequences of European settlement in the sixteenth-century changed the ecosystem drastically with the introduction of plant species, diseases and the raising of livestock such as, chickens, pigs, donkeys, goats, sheep, cattle, horses, and mules. Today, there are about 42,000 Otomi people living in the Sierra Madre mountains, in the Mexican state of Hidalgo. Smaller populations are also found scattered in states such as Puebla and Veracruz. Most of these societies still continue to survive through subsistence farming or market agriculture, with most Otomi men working in the cities during off seasons.

Melville, Elinor G. K. A Plague of Sheep: Environmental Consequences of the Conquest of Mexico. Studies in Environment and History. Cambridge England ; New York, NY, USA: Cambridge University Press, 1994.