In Mexico, floating farms from the Aztec era are being restored

Some scientists from the National Autonomous University of Mexico (UNAM), in collaboration with local farmers, are promoting a program to restore the chinampas in the Xochimilco wetland, south of Mexico City.The chinampas are delicious small artificial islands created by the Aztecs, a sort of floating farms that play a fundamental role in the identity of Xochimilco, an area of ​​lakes and swamps that has survived urbanization and the expansion of industrial agriculture.The objective of the initiative is to preserve the chinampas system and all living beings that depend on it.A system which, in 1987, was declared a World Heritage Site by UNESCO precisely because of its cultural importance and ecological value.

The chinampas, once used only to grow vegetables and leafy greens, are now largely abandoned or transformed into, for example, football fields and restaurants.In 2018, FAO data revealed that only 17% of the 20,922 chinampas it was still cultivated in the traditional way.The rest had been abandoned or converted.Inevitably, the transformation of the chinampas has also led to changes in local biodiversity, putting species such as the axolot, an iconic salamander of Xochimilco, at risk.According to a 2015 study, axolot density dropped from 6,000 per square kilometer in 1998 to just 100 per square kilometer in 2008.In 10 years, a 98% decrease, and the decline continues.To reverse the trend, the UNAM Ecological Restoration Laboratory, together with local farmers, is therefore working to restore the area.Their strategy includes reducing invasive species such as carp and tilapia, environmental monitoring and the creation of “ecological refuges”.The project, in particular, involves the rehabilitation of chinampas and secondary canals, using aquatic plants as biofilters to improve water quality.This approach not only protects the asolotto, but it also restores the entire ecosystem.Since 2008, ecological refuges have been created, i.e. chinampas protected by structures that prevent the entry of invasive species and stabilized with willow trees.These refuges offer a safe habitat where species such as the axolot can complete their life cycle away from predators and polluted water.The long-term goal is to process at least 400 chinampas in the next 15 years.

However, this also requires political will and collaboration with governments.Currently, despite the ten-year origin of the project, only 40 chinampas have been rehabilitated.The positive note is that the benefits are already evident.Basilio Rodríguez, one of the farmers included in the initiative, restored the soil by removing sediment and stabilizing the island.And today, his chinampa is an example of how sustainable agriculture can coexist with environmental conservation.The rehabilitation of chinampas, in fact, not only improves water quality and increases agricultural yield, but also promotes greater biodiversity and a healthier ecosystem, as well as provides protection against climate change.In general, wetlands like Xochimilco are strategic ecosystems to mitigate the effects of the ecological crisis.This is mainly due to the important role they play in terms of carbon capture and storage, but also because they act as “shock absorbers” of extreme weather events, even more so if they are located in a city of the proportions of Mexico City.In short, – ha commented Carlos Sumano, member of the Ecological Restoration Laboratory – «a concrete example of how humanity can coexist in an ecosystem, producing food, satisfying its own needs and, at the same time, conserving and respecting the environment.The chinampas system confirms that this is real, that it is possible, that it can be done, that it works."

by Simone Valeri