Almost in the U.S. lives with a mental illness. That statistic is similar worldwide, with an people currently dealing with a mental or neurological disorder. Of those, only about a third seek treatment.

Interacting with nature is starting to be recognized as one way to improve mental health. A number of scientific studies have shown that nature experiences may benefit people鈥檚 psychological well-being and cognitive function. But it has been difficult to find ways to quantify these benefits in a useful manner for cities or organizations that want to integrate nature to improve mental health.

Now, an international team led by the 91爆料 and Stanford University has created a framework for how city planners and municipalities around the world can start to measure the mental health benefits of nature and incorporate those into plans and policies for cities and their residents. The was published July 24 in .

“Thinking about the direct mental health benefits that nature contact provides is important to take into account when planning how to conserve nature and integrate it into our cities,” said , lead author and an assistant professor at the 91爆料 School of Environmental and Forest Sciences. “The purpose of this paper is to provide a conceptual model of one way we can start to think about doing this.”

The study brought together more than two dozen leading experts in the natural, social and health sciences who study aspects of how nature can benefit human well-being. Their first step was to establish a baseline, collective agreement regarding the understanding of the impacts of nature experience on aspects of cognitive functioning, emotional well-being and other dimensions of mental health.

鈥淚n hundreds of studies, nature experience is associated with increased happiness, social engagement, and manageability of life tasks, and decreased mental distress,” said senior author , faculty director at the Stanford Natural Capital Project. “In addition, nature experience is linked to improved cognitive functioning, memory and attention, imagination and creativity, and children鈥檚 school performance. These links span many dimensions of human experience, and include a greater sense of meaning and purpose in life.鈥�

While this line of study is still emerging, experts agree that nature can reduce risk factors for some types of mental illnesses and improve psychological well-being. They also agree that opportunities for nature experiences are dwindling for many people around the world because of urban growth.

“For millennia, many different cultures, traditions, and religious and spiritual practices have spoken directly to our deep relationship with nature. And more recently, using other sets of tools from psychology, public health, landscape architecture and medicine, evidence has been steadily gathering in this emerging, interdisciplinary field,” Bratman said.

The study outlines how city planners, landscape architects, developers and others could eventually anticipate the mental health impacts of decisions related to the environment.

Many governments already consider this with regard to other aspects of human health. For example, trees are planted in cities to improve air quality or reduce urban heat island effects, and parks are built in specific neighborhoods to encourage physical activity. But these actions don’t usually directly factor in the mental health benefits that trees or a restored park might provide.

“We have entered the urban century, with two-thirds of humanity projected to be living in cities by 2050. At the same time, there is an awakening underway today, to the many values of nature and the risks and costs of its loss,” Daily said. “This new work can help inform investments in livability and sustainability of the world鈥檚 cities.”

The research team built a conceptual model that can be used to make meaningful, informed decisions about environmental projects and how they may impact mental health. It includes four steps for planners to consider: elements of nature included in a project, say at a school or across the whole city; the amount of contact people will have with nature; how people interact with nature; and how people may benefit from those interactions, based on the latest scientific evidence.

The researchers hope this tool will be especially useful in considering the possible mental health repercussions of adding 鈥� or taking away 鈥� nature in underserved communities.

“If the evidence shows that nature contact helps to buffer against negative impacts from other environmental predictors of health, then access to these landscapes can be considered a matter of environmental justice. We hope this framework will contribute to this discussion,” Bratman said. “Eventually, it could be developed and potentially used to help address health disparities in underserved communities.”

Other 91爆料 co-authors are , , and . Other Stanford University co-authors are , and . See the for a full list of co-authors.

This study was funded by the Natural Capital Project, John Miller, the Doug Walker Endowed Professorship, Craig McKibben and Sarah Merner, the Marianne and Marcus Wallenberg Foundation, the Winslow Foundation, the George Rudolf Fellowship Fund, the Victoria and David Rogers Fund, and the Mr. & Mrs. Dean A. McGee Fund.

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For more information, contact Bratman at bratman@uw.edu or 206-543-7591 and Daily at gdaily@stanford.edu or 650-723-9452.

Also see the from Stanford University.

That humans and the cities we build affect the ecosystem and even drive some evolutionary change in species’ traits is already known. The signs are small but striking: in cities are getting bigger and in rivers are getting smaller; in urban areas are growing tamer and bolder, outcompeting their country cousins.

What’s new is that these evolutionary changes are happening much more quickly than previously thought, and have potential impacts on ecosystem function on a contemporary scale. Not in the distant future, that is 鈥� but now.

A new by of the 91爆料 College of Built Environments’ published this month in the journal Trends in Ecology & Evolution suggests that if human-driven evolutionary change affects the functioning of ecosystems 鈥� as evidence is showing 鈥� it “may have significant implications for ecological and human well-being.”

Alberti, a professor of urban design and planning, said that until recently it was assumed that evolutionary change would take too long to affect ecological processes quite so immediately. Such thinking has prevented evidence from coming together “in a way that can only emerge through a cross-disciplinary lens,” she said, observing the interactions between humans and natural processes.

“We now have evidence that there is rapid evolution. These changes may affect the state of the environment now. This is what’s called eco-evolutionary feedback.

“Cities are not simply affecting biodiversity by reducing the number and variety of species that live in urban habitats,” Alberti said. Humans in cities are causing organisms to undergo accelerated evolutionary changes “that have effects on ecosystem functions such as biodiversity, nutrient cycling, seed dispersal, detoxification, food production and ultimately on human health and well-being.”

In the paper, Alberti systematically reviews evidence of “human signatures,” or documented examples of human-caused trait changes in fish, birds, mammals and plants, and their effects on ecosystem function.

In addition to the shrinking salmon, she cites earthworms with increased tolerance to metals, seeds of some plants dispersing less effectively and a type of urban mouse that is a “critical host” for the ticks that carry Lyme disease, leading to spikes in human exposure to the illness.

Songbirds are becoming tamer and bolder and also are changing their tunes to ensure their acoustic signals are not lost in the noisy urban background. European blackbirds are becoming sedentary and have changed their migratory behavior in response to urbanization.

Humans in cities cause these changes through a variety of ways, Alberti said. Our urbanization alters and breaks up natural vegetation patterns, introduces toxic pollutants and novel disturbances such as noise and light and increases the temperature. Human presence also changes the availability of resources such as food and water, altering the life cycle of many species.

Alberti said the emerging evidence prompts serious questions with implications for the focus and design of future studies:

• Can global rapid urbanization indeed affect the course of Earth’s evolution?
• Is urbanization moving the planet closer to an environmental tipping point on the scale of the that introduced oxygen into the atmosphere more than 2 billion years ago?
• Might different patterns of urbanization alter the effect of human action on eco-evolution?

Still, Alberti said hers is not a “catastrophic” perspective, but one that highlights both the challenges and the unique opportunity that humans have in shaping the evolution of planet Earth.

Ecosystems in urban environments are a sort of hybrid, she said: “It is their hybrid nature that makes them unstable, but also capable of innovating.” She explores the theme further in a book to be published in spring 2016, titled “Cities as Hybrid Ecosystems.”

“We can drive urbanizing ecosystems to collapse 鈥� or we can consciously steer them toward a resilient and sustainable future,” Alberti said. “The question is whether we become aware of the role we are playing.”

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For more information, contact Alberti at 206-295-7985 or malberti@uw.edu. Twitter: @ma003.