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Editor’s note: This article is part of a series about sustainable cities. Read the other articles: "Sustaining our cities," "Curbing urban sprawl," "Room to grow," "Easing off the gas," "A city that you love" and "Sustainability – one building at a time."
When you think of ecologists, you might imagine people trekking out into the deep wilderness, binoculars in one hand and field notebook in the other. Miles from civilization, they diligently collect samples of exotic plants and insects that would never be found within city limits.
However, there are a few problems with this romanticized version of an ecologist, one of them being the idea of wilderness untouched by humans.
“We’ve recognized that there really aren’t such places, or very few such places left on Earth,” says Nancy Grimm, an ecologist herself who has worked in the field for more than 30 years. She is a professor in Arizona State University’s School of Life Sciences and director of the Central Arizona-Phoenix Long-Term Ecological Research (CAP LTER) project, which focuses on ecology not in the pristine wilderness, but in the metropolitan city.
Launched in 1997, CAP LTER is one of 26 LTER sites scattered across the United States. These projects, funded by the National Science Foundation, aim to produce a comprehensive picture of the changes in diverse ecosystem types over long timescales. CAP LTER, which is based at ASU and focuses on the metro Phoenix area, is one of only two sites that examine urban ecosystems (the other is in Baltimore).
Specifically, the Phoenix site answers questions about ecosystem services, which are benefits provided to people by the environment or wildlife. These include a variety of goods and services such as food, water, medicines, timber, flood and erosion control, recreation and creative inspiration.
CAP LTER scientists are also learning about how humans interact with nature in their city. To do this, a team of researchers in ecology, sociology, climatology, anthropology, engineering and other fields are working together to produce transformational scientific findings.
One of the concepts that CAP LTER has pioneered is the idea of a designer ecosystem. But the term “designer” isn’t meant to conjure images of a fancy streambed or expensive cactus. Instead, a designer ecosystem is one that has been partially constructed by people, but also includes some natural ecological components.
“If you take, for instance, the contrast between a concrete canal and a natural stream, a designer ecosystem might be something that is sort of somewhere in the middle,” says Grimm.
Another way to think about designer ecosystems is to imagine the different ways people landscape their front yards.
“Everybody has seen the xeric desert – or Disney desert they’re sometimes called – residential landscapes in the city,” Grimm says. One might think these “designed” deserts would function the same ecologically as the real thing. However, CAP LTER scientists have found that they in fact behave quite differently from native desert systems.
“It’s not enough to mimic the way something looks and even the broad types of plants, because individual species are important,” Grimm says. For example, scientists have found that non-native plant species, despite looking similar to those you’d find naturally in the desert, won’t attract native pollinators. So while a yard may look like a tiny version of the Arizona desert, it probably won’t operate like one on an ecological level.
However, incorporating nature into human systems can prove to be beneficial in certain scenarios.
“We have found that adding a little bit of nature into the ways we deal with things like absorbing storm water, or slowing down storm water, or cleaning up wastewater, can actually really improve the efficiency at a reduced cost,” Grimm says.
For example, CAP LTER scientists have been conducting research at Tres Rios wetlands, constructed by the City of Phoenix as an alternative to traditional wastewater treatment. Tres Rios is located where the Salt, Gila and Agua Fria Rivers meet, and is fed by highly treated effluent from the 91st Avenue Wastewater Treatment Plant.
The project consists of a flood protection levee, effluent pump station, emergent wetlands, and riparian corridors and open water marsh areas. Researchers are studying how well urban wetlands can treat wastewater while also providing ecosystem services like wildlife habitat.
Ultimately, being aware of how designer ecosystems function can help policymakers and urban planners optimize ecosystem services and promote sustainability. This is especially important given projections that 66 percent of the world’s population will live in cities by 2050, according to the United Nations.
“It’s an imperative to understand how we make cities sustainable, because like it or not, that’s where most people are going to be living,” Grimm says.
Because sustainability is a measure of the environmental, social and economic aspects of life, it’s important to know how those areas are connected, and when they may conflict. That’s why CAP LTER research is critical.
“We’ve embraced the idea of considering how the ecological, social and technological aspect of urban systems interact and feed back with each other to create conditions that could result in a sustainable trajectory,” Grimm says.
The School of Life Sciences is a unit of the College of Liberal Arts and Sciences. Nancy Grimm is also a senior sustainability scientist in the Julie Ann Wrigley Global Institute of Sustainability.
Written by Allie Nicodemo, Office of Knowledge Enterprise Development