This canoe is going to collect a very special harvest. It's right here in the heart of Mexico City, and it has hundreds of years of history.

Welcome to the chinampas. These artificial floating gardens are some of the last remnants of the Aztec empire. They're rapidly disappearing. But this farmer is stepping up to keep them alive.

"One of the first memories I have when I was a child was my grandfather planting. And in the Chinampa he would always plant flowers. So for me, coming to the chinampa was like paradise.”

Meet Cassandra. Chinampas have been in her family for generations, but as this tradition is usually passed from father to son, she went to university to pursue a career abroad.

But when she came back years later, what she saw shocked her. It was time to come home.

"Every time I came back I saw the degradation of the ecosystem, I saw the abandonment of the land, I saw how the water levels were getting lower and lower. And I think that's when I started to become aware that I was part of this space. And part of my responsibility was to safeguard it."

Many chinampass are now abandoned. They're also being turned into soccer fields or tourist attractions. Cassandra has been working for four years to restore this abandoned chinampa and now she maintains it, which isn't easy.

Here's what goes on in a chinampa. The main element is mud taken from the bottom of the canals and placed within a fence.

The mud is laid with branches and grass kind of like a big cake At the end trees are planted on top and their roots stabilize the whole structure. The base is ready for the nursery.

“The mud we use contains organic matter, minerals, and (volcanic) ash from thousands of years of the basin's existence.”

"We extract the mud, place it on the beds, and sow the seeds directly here. And this is part of the world's agricultural heritage."

Chinampas aren't just valuable for their cultural heritage. They also play a key role in restoring soil. This is essential not only for growing food, but also for storing carbon.

With soil this rich, you can have between five to eight harvests per year. It all depends on what you wanna grow.

Chinampas can grow a huge variety of crops, around 70 to 80 kinds, including corn, leafy greens, and even flowers. A traditional chinampa looks like this. No two are ever planted exactly the same.

“Xochimilco is not only important in terms of agriculture, chinampas, and biodiversity, but also in terms of ecosystem services for Mexico City.”

As this expert is pointing out, the area also helps cool the city, and that's not all. It's home to many animals and plants, it helps reduce flooding, and absorbs carbon from the atmosphere.

Mexico City did not always look like this. The city sits in a valley ringed by volcanoes, and lakes filled the basin in pre-Hispanic times.

The Aztecs settled here and built Tenochtitlan, which became the capital of the vast empire. Chinampas popped up across the city to feed a dense population.

When the Spanish arrived in 1519, they started draining the lakes and paving over wetlands. Only a few intact chinampas remained, mainly in the borough of Xochimilco.

"So what can we as farmers do to remedy this? For more than eight years I have been collaborating with UNAM (Mexico's National Autonomous University) in an ecological restoration project here in the area. For a long time I was looking for initiatives or projects that had congruence in the territory and that contributed a little bit more in the social part, because I feel that it is what is most damaged."

Here, at the National Autonomous University of Mexico, scientists have been working for two decades to help farmers protect their land.

“There are several factors that have put Xochimilco at risk, mainly urbanization, poor water quality, and the introduction of exotic species.”

"Chinampas are an artificial agroecosystem, right? It was created precisely to supply food in pre-Hispanic times to the entire population. And that lasts to this day. So, the way to preserve Xochimilco is to also preserve the chinampa."

The team is working to clean and restore the canals in the chinampas.

They're adding biofilters made of aquatic plants, which also prevent the entry of invasive species. These canals are a refuge for the critically endangered Mexican axolotl. If this salamander disappears, many other species will too.

Currently, the project has created refuges with biofilters and 36 chinampas.

Studies estimate that there are about 16,000 potential chinampes to restore in all of Xochimilco. But convincing farmers to abandon agrochemicals is tough. Still, the product manages to add three to four new ones each year.

"Although it may sound like a very small number, it actually represents a significant change. And working with Cassandra and all the other farmers has given us the opportunity to remove that barrier."

So it's really hard to compete with big industrial farms. And these days, just growing crops isn't enough to make chinampass truly profitable. The key is to position these products as more than just food.

They're tied to the tradition and sustainability of Xochimilco. By selling directly to consumers, farmers reach new markets to get better, fairer prices.

"One of the things I enjoy most is sharing what I have learned with others. I like to think that each generation is a layer, a layer that keeps adding to the soil, enriching it. So every time I come here, I always think, I hope the layer I left behind is good enough for the next generation to have the same care (for their land) and the same way of thinking about the world."

AP video shot by Monica Wise

Produced by Lucía Torres and Teresa de Miguel

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EDITOR'S NOTE: This story is a collaboration between The Associated Press and Mongabay.

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