The Art of Natural Capital: Visualizing Ecosystem Services in Urban Contexts
mapping the benefits of nature in cities
You’re taking a walk in your local park. It’s springtime: daffodils push through mulch delivered from the community garden; to your left, a basketball game is in full swing, a cyclist whizzes by, and friends meet for coffee. Nearby, someone finally takes a deep breath after a grueling day at work. What this view of the park doesn’t quite capture is how the cooling effects of its green spaces could prevent heat-related visits to the ER; how it creates gathering places that enhance feelings of social connectedness.
Natural infrastructure, also frequently referred to as “green infrastructure” (such as parks, forests, street trees, community gardens, green roofs, and coastal vegetation), plays a central role in sustainable urban management. However, many of the benefits of “urban nature” are quiet and easy to take for granted, and often distributed unequally across a city’s neighborhoods. It remains a challenge for urban decision-makers to incorporate the values of natural infrastructure into formal design and planning.
By 2050, over 70% of the world’s population is expected to live in cities.1 If we want those cities to be as livable, breathable, and sustainable as possible we need a clear way to see exactly where urban nature is or could provide benefits to people, how much of each benefit it’s providing, and who is receiving them.
As one can imagine, in an urban setting, mapping and modeling ecosystem services might look a little different than in a vast rural watershed.
There are different categories of ecosystem services: provisioning (also known as material) services; regulating services; and cultural services. All these services are underpinned by supporting ecological functions sometimes called supporting services. Read on to see how two students in Stanford University’s natural capital course created a “zine” depicting visually how these services show up in a city park. You can also find a Q&A with them on the NatCap website.
Regulating services are broadly defined as: the benefits nature provides by moderating environmental conditions: controlling floods, regulating temperature, filtering water, and stabilizing local climate.
In an urban context this could look like: Nature-based rain-capture systems filter stormwater for reuse, trees and parks cool down heat islands, wetlands and green roofs absorb stormwater before it floods streets, and vegetation filters runoff before it reaches waterways. In Shenzhen, China, natural infrastructure reduced daily air temperatures by 3°C during hot summer days and helped avoid an estimated $25 billion in flood damages during a severe storm event.2
Using InVESTⓇ, this could look like: Using the Urban Cooling, Urban Flood Risk Mitigation, or Urban Stormwater Retention models to help map where nature is doing the most regulatory work, how much benefit it’s providing in biophysical and economic terms, and who is receiving that protection.
Provisioning services are broadly defined as: the tangible goods nature produces (food, clean water, and raw materials) that people can directly harvest and use.
In the urban context this looks like: Community gardens are a sneaky powerhouse: not only can they provide fresh produce and medicinal plants, but they can reduce household food expenses, and strengthen community resilience [read more about this from the NatCap project and report: “Vibrant Land: The Benefits of Food Forests and Urban Farms in San Antonio”]. People have grown food in urban spaces for centuries, particularly during times of economic and political stress. Today, interest in urban agriculture has grown alongside rising population density, shrinking green space, and increasing food insecurity – with urban food cultivation as one promising way to alleviate food deserts and bolster food security.
Using InVEST this could look like: Crop production models estimate yield and nutrient value for urban farms and food forests, helping cities identify where demand for local food production is highest.
Cultural Services, are broadly defined as: the non-tangible benefits people receive from nature: the ones that shape wellbeing, identity, and quality of life.
In the urban context this looks like: That same community garden plot, or the park down the street, are simultaneously spaces where people exercise, decompress, and meet their neighbors. Parks and trails support physical activity, linked to lower rates of obesity and cardiovascular disease. Access to green space is consistently associated with reduced stress, improved mood, and mental and physical wellbeing. Community gardens, in particular, have emerged across decades of research as one of the most reliable urban mental health interventions, outperforming many other engineered green-space solutions in terms of accessibility, frequency of use, and durability of benefits.
Using InVEST this could look like: Using the Urban Nature Access model, as well as recreation, scenic quality, and the soon-to-be-released mental health model.
Supporting services are defined as: the foundational ecological processes that make all other services possible.
In an urban setting this looks like: Soil and vegetation in parks, street tree pits, and green roofs cycle nutrients and filter water back into the ground. Urban soils can often be compacted and depleted, but are slowly rebuilt by natural processes in green spaces. Parks, gardens, and trees provide habitat for birds and other wildlife. Or,
Using InVEST this could look like: a habitat quality and habitat risk assessment to identify which urban ecosystems are healthy enough to support foundational processes like nutrient cycling, and to pinpoint which areas are at risk of losing these functions.
Several years ago, a team of NatCap scientists tested a range of tools under the Urban InVEST umbrella for cities around the world, alongside researchers from universities, government research institutes, and conservation organizations. This included applying in Paris, France; Lausanne, Switzerland; Shenzhen and Guangzhou, China; and several U.S. cities, including San Francisco and Minneapolis. In many cases, they worked with local partners to understand on-the-ground priorities. For example, in Paris (which inspired the Zine above) candidates in a municipal election were campaigning on the need for urban greenery, while in Minneapolis, planners were deciding how to repurpose underused golf course land.
In Paris, they looked at the Île-de-France region, which encompasses the Paris metropolitan area and its surrounding forests and farmland. It is an area that has faced intense pressure from population growth. The team examined the impact of land-use change on the value and distribution of ecosystem services to provide recommendations for future master plans.
The study found that in the last 35 years, urban development expanded from 18% of the land area to 23%. Today 23% of the Île-de-France region could be classified as “built-up.”
The total loss of natural and semi-natural areas since 1982 was 0.4%, a relatively small shift, yet one that triggered a domino effect on nature’s benefits.
7 of 8 of the critical ecosystem services (like carbon storage and water regulation) had each declined during this period.
The application of the Urban InVEST suite of models also highlighted a key equity gap: the areas with the lowest access to green space didn’t always overlap with the areas where new investment would most effectively reduce inequality.
(e.g., Ibid.)