Strolling through the forest under a canopy of pine trees along a path lined with shaggy native grass, Agustín Martínez Villarreal pauses to point out signs that the endangered volcano rabbit passed this way recently. The little creatures were a common sight during his boyhood here, says Martínez, 54, a Mexican peasant farmer and conservationist. Only a few thousand of these endemic animals, known locally as teporingo, remain today.
Perhaps even more remarkable than signs of the presence of the teporingo is the fact that its forest home is in Mexico City, the Western Hemisphere's most populous megacity. The United Nations defines a megacity as an urban area with over 10 million residents. Mexico City's greater metropolitan area, which includes nearby Cuernavaca and Toluca, is home to about 22 million people.
The term "urban forest" is often used to describe public parks and sidewalk shade trees. But I am standing with Martínez and several other members of a local conservation group, Grupo de Monitoreo Biológico de Milpa Alta, in an actual forest inside the Mexico City limits: the Water Forest.
The wind rustles through tree branches. Pine nettles crunch beneath our feet. The occasional bird adds its song to this natural chorus. Inside the hushed enclave of the Water Forest not even a car horn penetrates. Conservationists have taken to calling the Mexico City district of Milpa Alta and the surrounding region Mexico's "Water Forest" to underscore its importance to sustaining the capital's water supplies.
While Mexico City is infamous for being an asphalt jungle, 59 percent of the city's territory is actually conservation land. However, the official designation has not stopped illegal logging and urban sprawl from cutting farther each year into the stands of pine and oyamel trees and grasslands that sprawl across southern Mexico City.
Occasional police operations sweep up illegal loggers and seize marijuana and other illicit crops grown under the cover of the forest. But conservationists here complain that government enforcement efforts pay mere lip service to protecting the 87,291 hectares of conservation land inside the Mexico City limits.
In all, the Water Forest region covers nearly a thousand square miles of forest fragments and grasslands, encompasses four mountain ranges, and two adjacent Mexican states—Morelos and Mexico State—national parks such as La Marquesa, Ajusco, Desierto de los Leones, and other protected areas.
Martínez said he has seen changes to the forest unfold firsthand in his village, San Pedro Atocpan, one of the nine original villages in la Delegación de Milpa Alta (similar to a city ward). More than half of San Pedro's residents are comuneros, or communal farmers like him, descendants of the indigenous people who have lived here for millennia.
While it was once a largely isolated farming community, these days some San Pedro residents work the land, while others commute to city jobs. Nearly half the village residents are newcomers who moved here from somewhere else, Martínez says. It is a trend seen in other parts of Milpa Alta, as well, according to the Mexican government.
With its proximity to urban job centers, Milpa Alta is seeing explosive growth. While it is Mexico City's least populous city ward and home to some of the city's poorest and most marginalized residents, Milpa Alta's population growth has outpaced Mexico City's overall growth for decades.
In 1990, Milpa Alta residents numbered nearly 64,000, while Mexico City's total population was 8.2 million. By 2015, Mexico City's total population has grown to 8.9 million, while Milpa Alta's population had more than doubled to nearly 138,000 people, according to Mexico's federal Instituto Nacional de Estadística y Geografía (National Institute of Statistics and Geography).
Groundwater: The Unseen Natural Resource
Teporingos are not the only ones affected by rapid urbanization in the Water Forest, scientists say. There are enormously valuable natural resources underground too: four of the country's most important underground aquifers that provide much of greater Mexico City's water. That's like gold in a region so water-stressed that nearly 20 percent of the Mexico's capital city residents make do with water service for just a few hours day or a few days a week, according to la Comisión Nacional del Agua (National Water Commission).
Modern Mexico City is considered one of the world's leading "green" cities for its pollution-busting policies such as "one day without a car" that requires residents to leave their cars home one day a week. Yet the city had 262 days—more than two-thirds of the year—in which the air quality was considered bad in 2016, according to the most recent annual air quality report issued by the Mexico City government.
The Water Forest helps regulate man-made climate problems—urban forests in particular are well-known for filtering pollutants out of the air, like smog. It also safeguards the water cycle connected to two of the country's largest rivers, the Lerma and the Balsas, and the aquifers that supply about two-thirds of the metropolitan area's water.
Despite the water wealth beneath its citizens' feet, urban water demands have long outpaced supplies here. As much as 40 percent of the city's water supplies are imported from other parts of Mexico, while aging infrastructure and leaky pipes mean an estimated 40 percent of the water in the system never reaches the taps.
In some of the city's poorest and most populous neighborhoods, such as Iztapalapa, residents have no tap water at all and must purchase what they can afford at exorbitant prices from water trucks, so common that they are referred to locally as la pipa (the pipe).
Years of Changes
Though evidence of human habitation here goes back thousands of years, the basin region surrounding Mexico City still holds more than 2 percent of the world's biodiversity. Teporingos and Sierra Madre Sparrows—both endangered—live here, as well as pumas , bobcats, white-tailed deer, and at least 10 percent of the bird species known to Mexico, according to researchers.
While these animals and a wide variety of native plants have survived centuries of human uses and abuses, recent decades of explosive urban growth are taking a toll as human settlements encroach on all sides.
An estimated 2,400 hectares—the equivalent of nine football fields—are lost every day in the Water Forest region, according to el Instituto de Geografía de la Universidad Nacional Autónoma de México (the Institute of Geography at the Mexican National Autonomous University).
At this rate, experts warn, the Water Forest could be gone within the next half century unless something is done. In recent years, the city's municipal government has turned its attention to the forest.
In the meantime, Martínez, López ,and other members of the Milpa Alta conservation group are doing what they can to preserve what remains of their forest through tree planting and grasslands restoration, fire fighting, environmental education, and biological monitoring of their forest's fauna and flora.
Agents of Protection
Rapid urbanization is only one threat to the region's forests and grasslands. Poverty has led some of Milpa Alta's comuneros to resort to illegal logging on community land. Also increasingly common is illegally "renting" comunero land for large-scale cultivation of potato and other crops propelling more land clearing, as well as new concerns about agrochemical runoff polluting water downstream residents rely on.
"We are losing water in quantity and quality," said Jürgen Hoth, director of Conservation International's Water Forest Program in Mexico. "Both are problems for a sustainable future."
Hoth is working with Martínez and other members of Milpa Alta's Grupo de Monitoreo Biológico on experimental grasslands restoration. Together, they are also documenting ruddy-colored water that runs off the crop rows mixing with spring water bubbling out of the ground in gullies alongside cropland. The discolored water has a strong smell that Hoth says may indicate contamination for agrochemicals but says testing is needed to determine the extent of the problem.
The group's 12 members range from a university-trained forester to local people like Martínez with deep knowledge of Milpa Alta's ecosystems that come from a lifetime working and living on the land.
While they have different backgrounds, they share a commitment to preserving the forest and have known each other for years. Martínez and others in the group have worked side by side to fight forest fires and take part in government-sponsored forestry projects in the past before forming the local conservation organization four years ago.
"They are deeply engaged. They've been at it for awhile and know what they are doing," said Janice Astbury, a researcher at the Durham University in England, in an interview via Skype. Astbury got to know the group last year while in Mexico investigating innovative urban sustainability projects.
When the group initially formed four years ago, a grant from the Mexican government allowed them to purchase a pick-up truck, forestry equipment, and night cameras. The photos helped document the forest's fauna and flora for scientific reasons but also help a lot with community outreach, says Nancy López, who oversees educational efforts for el Grupo de Monitoreo Biológico de Milpa Alta.
They started talking with their neighbors about the forest's importance, launching public-service campaigns and photo exhibitions. They distributed beautiful handmade educational materials that are more like do-it-yourself 'zines illustrated with photos of the local fauna and flora that López hopes people will hang onto, taking the message inside to heart, instead of tossing them immediately in the trash. They sell calendars, notebooks, other nature-themed gifts to raise awareness, along with money to cover gas and other expenses of their restoration work in the forest; and visit classrooms, finding allies in elementary school kids and a local children's bird watching troop.
"It's a way we can awaken an interest in forest conservation in the next generation. Through the children, the parents get involved too," López said.
"Despite the many obstacles, we keep working," López said. "Each of us has other jobs to help us get by. We end up spending money from our pockets. But we're so passionate about the cause, we are willing to do it."
Rainwater and Flooding
Commitment like the one exhibited by members of this Milpa Alta conservation group is rare here. Over the last few decades, campesinos around the country have come to rely on the extra cash they can make from forestry projects financed by the Mexican government, the international community, and corporations. But conservationists say campesinos rarely take the initiative to continue the work once the funds are spent.
That is not to say that indigenous and campesino communities are not involved in successful forestry in Mexico. In fact, experts say some of the country's most successful community forestry projects are operated by indigenous people.
Though rural communities often resist adopting methods imposed from outside their communities, forestry projects work well here when local people are involved in decision-making and innovation, experts say.
The Milpa Alta group, for instance, has learned from past mistakes and taken up stances against government forestry methods they've found counterproductive, Hoth says.
In the Water Forest, "They are perhaps the best example of a community that has become the steward of the land," says Hoth, who also works with five other communities in the Water Forest region. Those other villages, he says, increasingly look to members of the Milpa Alta group as role models.
"But they are doing it pretty much without any payment and living already in pretty marginal conditions," he says. "So here's a very commendable effort that needs to be supported."
Hoth is working with the Milpa Alta group to restore grasslands that play an essential, if often overlooked, role in capturing rainwater and channeling it through the region's porous volcanic soil to recharge groundwater.
As native grasses are replaced by human settlements and poorly sited tree-planting projects, experts say their loss contributes to flooding in densely populated urban areas downstream, while reducing water available to recharge aquifers. The latter is a problem not limited to Mexico. According to a growing body of scientific evidence, afforestation of grasslands has become a matter of concern in several countries, as climate change mitigation efforts have opened a floodgate of funding for tree planting worldwide.
With funding from the Mexican foundation, Fundación Gonzalo Río Arronte, and technical support from Mexico's Colegio de Postgrados, Hoth and group members took cuttings of the native grasses, including species such as Muhlenbergia, Festuca, and Stipa, and planted them last year in degraded forest areas after nurturing the cuttings in a community greenhouse.
Their first experiment on half a hectare in Milpa Alta's Llano de Morales Valley had a 97 percent survival rate. So this year, they are expanding to project to 50 hectares (about 124 acres), this time forgoing the greenhouse altogether. They will expand on the experiment by directly transplanting cuttings taken from natural grasslands in one area to replant them where grassland has been degraded or cleared away altogether.
"If it works, it will save time and money," Hoth says.
Besides their conservation work, members of the group are experimenting with ways to make a living off the land, while still conserving the forest. While the megacity it supports may be the forest's biggest threat, it has certain advantages. One is the proximity to a large number of people who might help.
The Milpa Alta area regularly attracts weekend hikers, cyclists, birdwatchers, and other nature lovers. The group's members have built a few rustic cabins and dream of a day when they can support itself through ecotourism.
"There are people who still see logging as the only viable local economy," Martínez says. "We want to find alternatives that protect the environment while allowing everyone to make a living."
This story originally appeared at the website of global conservation news service Mongabay.com. Get updates on their stories delivered to your inbox, or follow @Mongabay on Facebook, Instagram, or Twitter.