Colombia's Gulf of Morrosquillo is home to thousands of mangroves. Their roots arc downward into salty seawater while their limbs climb upward — a mesmerizing entanglement of branches and leaves.

But the mangroves must compete with hotels, resorts and other financial ventures in the tourist-dependent area, which spans 325 miles of Caribbean coastline. One study found that between 1960 and 2011, the mangrove population in Colombia dropped by more than half, largely due to human activities such as development or trash dumping.

The burgeoning tourist destination of Rincón del Mar, for instance, is one of many towns along the gulf that was built on land cleared of the trees. And because there is no central garbage collection system, people's wrappers, bottles, bags and other refuse often end up in the mangroves that still stand.

In early 2020, the government signed a five-year, $300 million pact to promote tourism in the gulf area, where approximately 350,000 Colombians live. It called for, among other initiatives, building hotels, a hospital and aqueducts to alleviate a dearth of drinking water that threatens the growth of the tourism sector. But the plan could also put even more pressure on the mangroves, as well as the sea grasses, coral reefs and fisheries offshore.

For Gretchen Daily, threats like these are also moments of opportunity. "Nature is often just seen as kind of in the way of prosperity," she said. "What we're saying is that nature is crucial to prosperity."

Daily is a professor of biology at Stanford University and a pioneer in a field known as "natural capital." The term refers to the soil, air, water and other assets that nature has to offer. As a conservation model, it is rooted in the idea that nature has a measurable value to humans and that protection efforts must go far beyond walled-off reserves and be broadly integrated into development practice and planning.

She has spent more than 30 years developing the scientific underpinnings of natural capital and is the co-founder of the Natural Capital Project, which has grown to include a group of 250 partners around the world. The organization has integrated science into its cornerstone computer program to help governments and other stakeholders prioritize conservation.

By the time Daily and her team had identified the potential for impact in the Gulf of Morrosquillo, the coronavirus pandemic had confined the 56-year old to her home in Stanford, Calif. Zoom — which is decidedly not her natural habitat — became the norm.

But within a matter of months, the Natural Capital Project put together a report for the Colombian government detailing that more than a third, or 118 miles, of the coastline had high exposure to flooding and coastal erosion. Protecting and restoring mangroves, the authors said, could help with that issue — especially along two specific stretches of the coast, including Rincón, where local activists say they've removed many tons of trash.

Mangroves, the report highlighted, also nurture robust fisheries for local communities and sequester carbon at a rate two to four times greater than tropical rainforests. Left in their current state, the Morrosquillo mangroves will store 62 million tons of carbon by 2030 — the equivalent of taking 12 million cars off the road for a year — which could help the country toward its commitments under the Paris climate accord.

"Until now we didn't have the specific information in a simple way to show the importance of maintaining the mangroves," said Santiago Aparicio, director of environment and sustainable development for the Colombian department of national planning. He added, "you don't protect what you don't value."

The next step, he said, is to take the information to mayors and local officials to incorporate that value into their development plans. Aparicio says he would like to see them use the Natural Capital Project's work to, for instance, avoid building a bike path through priority mangroves. Another "ideal situation" would be using mangroves instead of cement walls as barriers against rising sea levels fueled by climate change.

For Daily, the work in Colombia has met all three of the criteria she uses when deciding whether to pursue a project: There must be a policy window that allows change; partners on the ground must be committed to that change; and the change must be scalable.

"I'm always looking for the win-win-win type situations," said Daily, whose colleagues say her optimism and charm are at the core of her success. The Natural Capital Project says it has now worked on some 1,700 projects around the world, and its open-source software has been downloaded in more than 185 countries.

She has been widely recognized for the work, including with the 2020 Tyler Prize for Environmental Achievement. She's also helped mentor the next generation of natural capital researchers and practitioners.

"There are many people who define themselves as ecosystem services scientists now," said Taylor Ricketts, one of the hundreds of people Daily has taught or advised over the years. "That's what she lit the spark for."

Daily's own scientific curiosity dates back to middle school — or rather, she says, to her walks on the way to school.

In 1977, Daily and her family lived in Kalbach, West Germany, where her father was stationed in the military. Then a 12-year-old, Daily and her sister would walk about a kilometer to class. It wasn't far. But the route passed a coal plant.

"You could taste the acid on the tongue," she said of the pollution. The smell of coal permeated the air. "That turned me on to science."

When it came time for college, Daily's parents urged her back to the United States. Grudgingly, she landed at Stanford, studying biology. Daily found the work grueling and contemplated quitting, staying only after her father encouraged her to explore a variety of disciplines — whatever she pleased.

She tried German literature, which didn't stick. Geology was too inert. "I like living life," she said, and by junior year she had "crawled" her way back to biology, where she's been ever since.

Daily's time as a Stanford student stretched through her doctorate work and put her at the center of early discussions on the science of natural capital, which provided a critical introduction to the theory. But her understanding of what it meant in practice, she said, came in the field, where she realized that both the problems and the potential for solutions were likely far greater than people realized.

"Reserves are too small, too few and too isolated to sustain enough nature," she explained. "We have to be able to integrate nature into our normal lives."

The 1990s saw a number of projects that began to reflect that vision. But, she said, "they were seat-of-the-pants in terms of implementing science."

It was Daily, her colleagues say, who changed that.

"Gretchen has really been the forerunner in clarifying the natural capital movement," said Carl Folke, director of the Beijer Institute of Ecological Economics at the Royal Swedish Academy of Sciences. He said one major catalyst came in late 1997, when Daily edited the book "Nature's Services: Societal Dependence on Natural Ecosystems" — recently referred to as "one of the most influential books published on the environment in the past 30 years."

"It brought these different case studies and insights that had emerged together," Folke said.

The effort to systematize natural capital took another step forward in 2005, when Daily and two colleagues founded the Natural Capital Project. The organization, which is housed at Stanford, is in many ways an embodiment of Daily's own approach to the problem.

"Gretchen's scholarship has been so revolutionary. … She changed the whole concept that nature should be protected for itself," said Alejandra Echeverri, Daily's postdoctoral advisee and the Natural Capital Project's main liaison with the Colombian government. "She came up with this idea that nature should be used for people, in a way that conservation should allow both people and nature to thrive."

Over the years, Daily has been involved in dozens of natural capital initiatives around the globe. It always starts, she said, from a foundation of basic science.

But to help turn science into tangible outcomes, Daily and the Natural Capital Project combined their research with mapping data to create a software called InVEST, which stands for "Integrated Valuation of Ecosystem Services and Trade-offs." It can help guide policymakers by pinpointing where, and for whom, conservation efforts can have the greatest payoff.

InVEST, Daily said, has enabled them to identify conservation priorities around the globe. But there has been a particularly significant impact in China — a country Daily has spent as much as two months a year in since 2009. In 2016, Daily and her colleagues published a paper in the journal Science showing that nearly half of the land in the country was zoned for protection or restoration; a figure that she said keeps growing.

"China was committing to this whole vision of an ecological society, but they didn't have science to basically calculate the return on investment to protect and restore the most critical natural capital," said Daily. "We came in with that."

With Daily at the helm, the Natural Capital Project has recently started applying InVEST at the urban level — including in China, France and the United States. In the San Francisco Bay area, they used the software to estimate the economic toll of flooding due to sea-level rise — an effect of climate change — and search for potential solutions. The organization found that each instance of flooding can amount to hundreds of millions of dollars in costs, and they've highlighted locations in the bay where green infrastructure development would benefit the most people.

Some, though, balk at such a capitalist framing of nature. "You are effectively pushing the natural world even further into the system that is eating it alive," said environmental activist George Monbiot during a 2014 lecture. Four years later he wrote in The Guardian that, "the natural capital agenda is the definitive expression of our disengagement from the living world."

And sometimes, natural capital projects backfire. In Mexico, a Bloomberg News investigation found that the country's Sowing Life program, which paid farmers to plant trees, may have actually encouraged people to cut down the jungle so that they could collect government payments for reforesting them.

"There's no way a natural capital approach is going to solve all human problems," said Daily, noting that there will probably always be cheating. And the work, she says, doesn't preclude the need for deep, systemic reform. But "usually the seeds of revolution are planted many years before the phase that people consider revolutionary."

In Colombia, officials are eager to participate in another of Daily's efforts: to have nations adopt "gross ecosystem product" — a measure of economic well-being that places nature at the fore. It's a metric that Daily says should be used alongside the more ubiquitous gross domestic product.

"For decades people have been noting the shortcomings of GDP, but politically it's always been too fraught to remedy," said Daily. "It's time to deploy something new."

Gross ecosystem product is, in many ways, a culmination of much of Daily's work. Along with others, she has lobbied the United Nations to make it an official metric. A climactic meeting on the issue was scheduled for February 2020 at U.N. headquarters. But then the pandemic hit.

"Missing that trip to New York was really crushing," said Daily, who along with more than 100 other participants moved their conversations online. Zoom meetings would often take place in the middle of the night for Daily, who would take the calls in her garage to avoid waking her family. She would attempt to stay warm while fiddling with PowerPoint presentations.

But a year later, in March, the push bore results when the United Nations Statistical Commission adopted the standard. "This is a historic step forward toward transforming how we view and value nature," U.N. Secretary General António Guterres said.

Daily heard the news by email, and it brought tears.

"It gave me a feeling of hope," she said.