It took a 40-minute taxi ride through the 4th largest city in the world to get there: on six-lane highways and cobblestone back alleys, among skyscrapers, apartment buildings, shops, and shacks. Once on foot we wandered through an over-crowded parking lot toward a decadent shrine to Our Lady of Guadalupe that marked the entrance to the Xochimilco wetlands. Colorful stalls lined the entire walk down the embarcadero (pier), and vendors sold handmade crafts and food. The canal itself was crowded with boats and passengers, nearly hidden by the buildings and concrete lining the edges of the wetland. Without online maps, finding these wetlands among the urban sprawl of Mexico City would have been nearly impossible.
Where is Xochimilco?
Xochimilco (pronounced zo-chee-MILK-oh) is a 25 km2 highly-altered, culturally-important wetland in the Federal District of Mexico City, Mexico. This wetland was first altered during the height of the Aztec civilization in 500 CE. As populations and the need for food grew, the Aztecs converted Lake Xochimilco into a series of islands and channels. They dug canals throughout the lake and used the soil to build chinampas, or garden islands. Chinampas were edged with layers of mud and plant material then filled to create land for growing crops.
During the Aztec Era, constructed chinampas covered an area of nearly 120 km2. Highly organic soils and a constant supply of fresh water and fertilizer meant the land was rich, producing unheard of amounts of corn. While crops changed over the years, the Xochimilco chinampas are still heavily used for agriculture. Ecotourism on trajineras (boats) in the canals throughout Xochimilco is also an important economic driver for the region. However, with huge population growth in Mexico City and the outward expansion of the city, development is encroaching on these culturally and economically important wetlands.
Why are Xochimilco wetlands at risk?
Wetlands are one of the most threatened habitats in the world, and conversion of land for agricultural use is a major factor in habitat loss. Ironically, in Xochimilco, urban development is threatening both wetlands and the historic agriculture practices they support. As urbanization continues in this region, understanding the impacts of development on the sustainability (or longevity) of Xochimilco is important in order for local governments to make decisions about how to preserve this threatened ecosystem.
The problems facing Xochimilco wetlands are numerous. Throughout the region, water quality issues and groundwater removal have led to abandonment of chinampas as historic agricultural practices become unprofitable. A decline in this globally unique ecosystem will also impact the ecotourism economy driven by boat traffic around these beautiful wetlands. To better understand what factors are influencing sustainability of these wetlands and the traditional agriculture they support, Pablo Torres-Lima of Universidad Autonoma Metropolicana – Xochimilco and his colleagues interviewed local residents and farmers of chinampas in a northern section of Xochimilco. They asked participants questions about regional, environmental, and social factors that may have an impact on the sustainability of Xochimilco wetlands.
What do local residents think are the major issues?
During their study, Torres-Lima and his colleagues found that residents were mostly concerned with development of unused chinampas for housing, hydrologic (water-related) changes caused by municipal sewer discharge into the Xochimilco wetlands, and the growth of invasive species like water hyacinth (Eichornia crassipes). These factors, along with chemical and pesticide usage, were perceived to decrease sustainability of Xochimilco wetlands and the agriculture taking place on active chinampas.
Alternatively, factors thought to increase sustainability of Xochimilco included restoration of historic canal hydrology through levee repair and dredging (digging out waterways to encourage and deepen water flow), removal of trash in waterways, use of organic and traditional agricultural practices, and re-introduction of native plant species.
What are the next steps towards conservation?
While local residents and chinampas farmers were very concerned with the sustainability of Xochimilco wetlands, they demonstrated very little interest in or ability to personally work to improve environmental issues. However, other studies have shown that people who express concern over environmental issues are more likely to support public policy changes that improve ecosystem health, even if they are not willing or able to make related changes in their work or home.
The level of concern about urbanization, infrastructure, and Xochimilco’s sustainability indicates there would be reasonable support for policies that regulate development in this ecosystem. Studies like that of Torres-Lima and colleagues are important for helping identify issues in threatened environments. By understanding what residents perceive to be important issues, local government can develop plans that improve ecosystem sustainability while directly addressing local concerns.
As we floated down crowded canals on a trajinera, the cultural importance of these wetlands was evident. Farmers tended gardens of flowers growing lush on chinampas lining the canal, mariachi bands floated by playing songs, and tourists laughed, drinking beer and eating food purchased from vendors in canoes. Similar scenes have been playing out in Xochimilco for over 1,000 years, but without a change in public policy and conservation efforts, these wetlands will continue to degrade and disappear.
Reference: Torres-Lima, P., K. Conway-Gomez, and R. Buentello-Sanchez. 2018. Socio-environmental perception of an urban wetland and sustainability scenarios: a case study in Mexico City. Wetlands. 38:169-181.