This blog post was written by Sarah Mason as part of the Spring 2018 UGA Urban Ecology class.
On my first trip to New Orleans, I did a lot of thinking. Bourbon Street is notorious for hosting a good time, and for good reason. Unfortunately, the cost of a good time includes a lot of abandoned cans, plastic cups, and bottles left in the street. When it rains some of the water joins the neglected litter sitting on the sides of the street, creating dark puddles. It was a linear system–the rain came down and most of it idled in the streets instead of being soaked back up into the Earth. How could we make this process more cyclical? But first, what is a linear system versus a cyclical system? In his book, The Ecology of Commerce, Paul Hawken (2010) writes, “Hazardous wastes are the result of a linear system in which the end products of resources and energy inputs are neither cycled nor returned. Nature is by definition cyclical; there is virtually no waste in the natural world that does not provide food for other living systems. If there were waste, we wouldn’t have survived four billion years of evolution, because linear systems use up and exhaust resources. In the natural world, all processes, directly or indirectly, result in food for other species.”
With that in mind, I’d like to pose a question: How can urban areas incorporate green infrastructure to mimic the cyclical nature of ecosystem services? This blog post is designed to answer that question in three segments: the first paragraph outlines common water issues in urban centers, the second defines ecosystem services and what they do for us in more natural areas, and the third explains green infrastructure and how implementing it into our cities allow for ecosystem services to take place.
So, why do we need to rethink how we build and rebuild our urban areas with ecosystem services in mind? Well, let’s go back to Bourbon Street. Some of that polluted water that one might see sitting in the street will also make up urban runoff—or the water that makes its way from our streets into the gutters and eventually back into the watershed, carrying our pollution with it. Ultimately that same water can end up in any part of the water cycle and in any part of the world. If we think about this further, the same impervious surfaces (surfaces like roads, roofs, and sidewalks that water can’t penetrate through) that aren’t allowing water to easily return to the watershed are also making it extremely easy for flood events to occur. If an increase in the volume of rainfall in any given city overwhelms the water systems, the water will overflow into the streets and potentially the buildings and homes there as well. As one may have already guessed, these problems aren’t just happening on Bourbon Street. They’re prevalent in cities and towns all over the globe.
Urban Runoff: Rainwater in urban areas mixes with pollution and eventually makes its way back into our watersheds. Photo credit: Krista Capps
Quite simply put, ecosystem services are services that an ecosystem provides free of charge and without being asked. These services can be split up into four different categories (Mannion, A.M., 2013): supporting services, provisioning services, regulating services, and cultural services. Supporting services include things like the water cycle, the formation of soils, and photosynthesis—the process in which plants use sunlight to create their own food. Provisioning services include the food, biomass fuel, and freshwater that an ecosystem provides for us. Regulating systems are exactly what they sound like—they include the regulation of climate, flood, and disease, as well as water purification. Lastly, cultural services include the aesthetic, spiritual, educational, and recreational values that we derive from the environment. As I suggested before, this all happens without any prompting from us and would still happen if humanity vanished from Earth tomorrow.
Ecosystem Services: There are four types of ecosystem services: Regulating, Cultural, Supporting, and Provisioning. Photo Credit: Earthwise Aware
Now, what exactly is green infrastructure? Green infrastructure is an emerging planning and design concept to mitigate urban flooding (Liu, W., Chen, W., & Peng, C., 2014). Examples of green infrastructure would include rain gardens, permeable pavements, urban gardens, rooftop gardens and increased urban tree canopy.
Green Infrastructure: A rain garden in the Proctor Creek Watershed. Photo Credit: Krista Capps
Incorporating green infrastructure allows for ecosystem services to take place, as well as break up impervious surfaces in order to reduce flooding. So now we have arrived at our destination, folks. Implementing green infrastructure helps us mimic the cyclical nature of ecosystem services because ecosystem services are cyclical by nature. Simply adding more green to our cities allows for water runoff regulation, nutrient cycling, water cycling, and all of the other services to boot. Granted, the answer is easier to come to than it is to actually put into practice in our cities. However, if we don’t make the decision to improve our cities on our own, the decision could be made for us in the near future.
For more information on green infrastructure: https://www.epa.gov/green-infrastructure/what-green-infrastructure#greenstreetsandalleys
Terms and Definitions
- Urban Tree Canopy: The layer of tree cover above a given area.
- Watershed: A land area that channels rainfall and snowmelt to creeks, streams, and rivers, and eventually to outflow points such as reservoirs, bays, and the ocean. (U.S. Department of Commerce, 2017)
References
Hawken, P. (2010). The ecology of commerce: A declaration of sustainability. New York: Harper Business.
Liu, W., Chen, W., & Peng, C. (2014). Assessing the effectiveness of green infrastructures on urban flooding reduction: A community scale study [Abstract]. Ecological Modelling.
Mannion, A. M. (2013). Ecosystem services. Salem Press Encyclopedia Of Science.
US Department of Commerce. (2017, November 30). What is a watershed? Retrieved April 01, 2018, from https://oceanservice.noaa.gov/facts/watershed.html