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Our Urban Planet

As the human population balloons and cities sprawl, ecological studies in urban areas are following suit. Nature has always been a component of cities – we can’t escape it after all, as hard as we may try – but urban nature (and the enhancement of it) has become increasingly important as the human species continues to urbanize. More and more we are seeing the importance of melding the built environment with the natural one. Our motivations are diverse – albeit largely anthropocentric. But that’s fine. As we make improvements to the live-ability of cities for human’s sake, other living beings benefit. We are finding ways to get along with our neighbors, and we are learning to appreciate and value them as well.

Since 2008, the world’s urban population has outnumbered its rural population, and it is predicted that by 2050, more than two-thirds of humans will be urbanites. Immense resources are required to support such large, concentrated populations, and most of these resources are produced outside of urban areas. This results in an ecological footprint that is significantly larger than the city itself. Additionally, waste and pollution produced within cities negatively effects surrounding areas and beyond in abundant ways.

st louis

In May of this year, Science put out a special issue entitled, “Urban Planet,” which features a series of articles that address some of the latest research in urban ecology and discuss current developments and future research needs – a sort of state of the union address for urban ecology in 2016. A series of 13 articles covered diverse topics including city-integrated renewable energy, innovative solutions to water challenges, transportation and air pollution, and food security in an urban world. Rodent-borne diseases in urban slums, creating sustainable cities in China, and Vancouver’s push to become the “greenest city” were also features of this special issue.

The issue serves to highlight the importance of this field of study and the urgency there is in finding solutions to major environmental challenges. But it also offers hope. Bright minds are working towards solutions to this century’s biggest problems as we look towards a more sustainable future. The introduction emphasizes that “the rise of cities is not…all doom and gloom.” Urbanization has upsides: “consolidating human populations helps shrink our individual environmental footprints, and cities are serving as living laboratories for further improvements.”

Urban ecology is a relatively recent subfield of ecology. In The Ecological Future of Cities, Mark McDonnell and Ian MacGregor-Fors describe how it “arose in the 1990’s out of a need to increase our…understanding of the ecological and human dimensions of urban ecosystems.” Initially the field was mainly concerned with biodiversity and the ecosystem processes and services found within cities. Findings from these studies are now influencing urban planning, design, and management. Such decisions are also informed by more recent studies in the field of urban ecology, which has grown to include “issues of sustainability, environmental quality, and human well-being in urban ecosystems.”

The authors note that our ecological understanding of cities was waylaid because “nature within cites was long considered unworthy of study, except when it involved solving environmental problems that threatened human well-being.” Cities were perceived as unnatural because humans had “disrupt[ed] the natural ecological conditions and processes that scientists [were] attempting to understand.” Today, ecologists recognize that studies in the field of urban ecology help us better understand basic ecological principles, while also providing “valuable information for creating liveable, healthy, and resilient urban environments.”

Studies in urban ecology have also increased our understanding of the mechanisms involved in evolution and adaptation. To illustrate this, the authors offer examples of birds that modified their songs “to communicate at noisy locations” and plants that shifted their seed dispersal strategies to survive in “highly fragmented urban habitats.” The authors also highlight the importance of maintaining or restoring natural vegetation in urban areas in order to help preserve struggling species of plants and animals, citing a study that found that “fewer local plant extinctions occurred in cities that maintained at least 30% native vegetation cover.” Additionally, the authors note that “the scope of urban ecology research extends well beyond city limits,” since urbanization is partly to blame for numerous environmental issues including habitat loss and fragmentation, biodiversity loss, climate change, and invasive species.

In Living in Cities, Naturally, Terry Hartig and Peter Kahn, Jr. address the topic of mental health and urban living. While there is still much to learn about the relationship between the two, it is generally believed that viewing or spending time in nature can help improve one’s mental well-being. As the authors put it, “parks and green spaces” can be viewed as “health resources for urban populations,” and including natural areas and natural processes in the design and creation of cities is necessary “for psychological as well as ecological purposes.”

Green roofs

Green roofs are one way to add green space to urban areas. They help replace vegetation that was removed when buildings were constructed, and they offer numerous environmental benefits.

Interacting with nature in an urban setting can help people develop positive feelings about the natural world and may encourage support for environmental protection. The authors worry that if future generations grow up without an intimate connection to the natural world, elevated amounts of environmental degradation will be seen as normal and a feeling of urgency to protect the environment from continued degradation will fade. This is why including plentiful amounts of green space within cities is essential: “Providing opportunities for people to experience more robust, healthy, and even wilder forms of nature in cities offers an important solution to this collective loss of memory and can counter the shifting baseline.”

This special issue of Science highlights some of the current ecological and environmental research regarding urbanization. For a great introductory look at urban ecology and basic ecological principles, check out the book, Nature All Around Us. Also, expect to see many more urban ecology themed posts on Awkward Botany. Tell your friends.

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Book Review: Hellstrip Gardening, part one

Keeping a garden alive and thriving is replete with its inherent challenges. Plants have needs, and those needs vary by plant. Lots of sun might be great for one plant but harmful to another. Some plants are very drought tolerant and don’t require much water beyond what falls naturally from the sky, while others insist on regular supplemental irrigation. Plants also have preferred soil types, and that soil must provide a proper balance of nutrients. Then there is the litany of potential pests, diseases, and predators that can present themselves at any given moment. Frankly, it’s surprising that any garden stays alive, all things considered.

Some gardens have added challenges. They may be regularly visited (and trampled) by the public, who may or may not have pets in tow. They may be surrounded by paved surfaces which increase ambient air temperatures significantly and can introduce contaminants to the garden in the form of road salts, petrochemicals, fertilizers, sediments, and animal waste. They may encompass utility boxes, water meters, and road signs that require regular visits and occasional maintenance. All of these things describe the plight of a curbside garden, also known as a hellstrip – that section of green space between the road and the sidewalk. Comparatively, backyard gardens are veritable havens for plants.

Hellstrips have been on my mind for several years now. It all started back in graduate school while studying green roof technology. One of the macro benefits of green roofs is storm water mitigation. During a storm event, green roofs capture a greater proportion of precipitation compared to conventional roofs and slowly release it back into the environment. Storm water is a major issue in urban areas where the percentage of impervious surfaces is high. These surfaces prohibit precipitation from infiltrating the soil and recharging groundwater and nearby waterways. Instead, this water is rushed away and directed into either waste water treatment facilities or local waterways, carrying with it the contaminants that have collected on paved surfaces and rooftops. Gardens along roadways can be engineered to manage storm water in a similar way that green roofs do – capturing it, filtering it, and releasing it back into the environment at a slow pace – thereby minimizing the negative effects of storm water runoff.

A rain garden or bioswale planted in a hellstrip to help mitigate storm water runoff. (photo credit: epa.gov)

A rain garden or bioswale planted in a hellstrip to help mitigate storm water runoff (photo credit: epa.gov)

The hellstrip in front of my parent’s house has been the source of many headaches. It is another reason why hellstrips have been on my mind. It is a weed patch, but not intentionally so. I remember many years ago when my mom told me she was going to replace the weed patch with buffalograss. She was elated by the idea – little or no mowing, very little supplemental water, a cool alternative to conventional lawn. Now, years later after planting dozens of buffalograss plugs and making a concentrated effort to keep them alive and prospering, the hellstrip remains a weed patch. But my mom hasn’t given up hope. The hellstrip will be conquered in due time.

Riding my bike to work last summer, I regularly rode past a house that proudly displayed the potential that curbside gardens could reach. The house sits on the corner lot of an intersection that, due to the angle of the connecting roads, gives the lot a long triangular shape. This makes the hellstrip longer than most of the others in this neighborhood. On this lengthy strip, the owners have planted an expansive and diverse vegetable garden. While once upon a time vegetable gardens were largely confined to backyards, they have lately been making more regular appearances in front yards. Few, however, are as bold and as public as this one – a true hellstrip success.

Last year, garden writer and lawn alternative enthusiast, Evelyn Hadden, put out a book called, Hellstrip Gardening. When I discovered this, I was intrigued, especially considering all of the mulling over hellstrips I had been doing for so long. I was curious to learn what she had to say. It has taken me until now to read it, but it seems like an opportune time to do so. After all, we are in pre-spring, a time when garden planning is being done in earnest. Perhaps this book will give me some ideas and encouragement to tackle some hard to garden spots this year. And maybe this review (and Hadden’s book) will inspire you to do the same. After all, this approach (as Hadden suggests) doesn’t have to be limited to curbside garden beds and can, in fact, be applied to any garden with challenges beyond the norm (like gardens along driveways and in alleyways, for example). The ultimate goal, for me at least, will be to pass along whatever knowledge I gain from this to my parents so that we can address their hellstrip issues once and for all.

hellstrip gardening book

Hellstrip Gardening is organized into four sections: Inspirations, Situations, Creation, and Curbside-Worthy Plants. This review will also have multiple parts that will be posted as I read through the book. The first section of the book is intended to inspire and encourage – to show through words and pictures what others have done and to give you that “if they can do it, so can I” sort of feeling. It also introduces some of the challenges of gardening in hellstrips as Hadden visits 12 gardens across the United States and talks with the people who designed, installed, and maintain them. She tells the story of how the gardens came to be and showcases some of the plants and plant combinations that were used in each situation. The challenges will be fleshed out in the following section; these narratives are meant more to demonstrate what can be done. There are dozens of great photos throughout, and the short plant lists at the end of each profile are sure to be useful.

Now that we’re inspired, next week’s post will take a look at what Hadden has to say about addressing challenges and overcoming obstacles that are unique to hellstrip gardens.