Bird man

Bird Man, the artwork of Senegalese artist Soly Cissé, looms over the Banco National Park in Abidjan, Ivory Coast.

Introducing the Urban Ecosystems Collection

PLOS ONE announces their Urban Ecosystems Collection "We felt it was particularly important to reflect the interdisciplinary nature of contemporary research in urban contexts and highlight some of the innovative approaches being used to explore important issues in these dynamic, complex environments."

see their collections of articles at https://collections.plos.org/s/urban-ecosystems

Urban nature, green cities, still life

Sherman Aronson is a visual artist, working with drawing, watercolor and digital tools, who earned his BA at Penn in the College in 1971 and his masters in architecture from Penn  in 1973. He is a practicing architect in Philadelphia and an adjunct professor of architecture at Drexel University.

Mr. Aronson has always made drawings, sketches and designs, from high school art classes through college and architecture school. It is part of how he looks at the world, thinks about his work and dreams. As an architect, he works in historic preservation and adaptive reuse, transportation renovations, green design and sustainable building. He has been an advocate for energy conservation and building preservation since the 1980s, working with professional associations and through his teaching. His art is an extension of that interest and passion.

“Enhancing our perception and conscious awareness of our urban parks and streetscape plantings can support our subconscious behavior and appreciation of climate change and human responses. Finding delight in the landscape around us, at home, while traveling and in many settings is a way to express our deep connection to the living world we love,” he said.

Courtesy of https://almanac.upenn.edu/articles/urban-nature-green-cities-still-life-at-the-burrison-gallery

Finding nature in your city

WildArk.org does a great job of describing where the wild places are in various cities around the globe. Their main mission is to preserve species and ecosystems through education and research. Check out their website at https://wildark.org

Transitional ecologies and tactical urban artists

“We are optimistic that the combination of creativity, ingenuity and low-budget, DIY mindsets that are hallmarks of both ecologists and public artists will help collaborators transform abandoned space into exciting and informative destinations.”

From Transitional Ecology: embedding ecological

experiments into temporary urban public art

Adam D. Kay,1,* Elizabeth Scherber,1 Hunter Gaitan,1 and Amanda Lovelee2

1Department of Biology, University of St. Thomas, 2115 Summit Avenue, St. Paul, MN 55105, USA and 2Public Art St. Paul, 381 Wabasha St N, St. Paul, MN 55102, USA

Journal of Urban Ecology, 2019, 1–7

Clean, green cities poised to take shape

China is building high-rise forest towers. Courtesy of China Daily news:

"For example, in Nanjing, capital of Jiangsu province, two residential high-rises designed by Italian architect Stefano Boeri are being built.

When completed, the buildings will house 1,100 trees from 23 local species and 2,500 cascading plants and shrubs, which according to the architects, will absorb 25 metric tons of carbon dioxide each year and produce about 60 kilograms of oxygen a day.

To put that in perspective, removing 25 tons of carbon dioxide would be equivalent to taking five cars off the road for a year. Chinese cities have some of the most polluted air in the world."

read more from this article at: https://www.chinadailyhk.com/articles/29/48/153/1573015446133.html?newsId=111714

Toward an Urban Ecology: SCAPE

Kate Orff, 2017 MacArthur Fellow, has an optimistic and transformative message about our world: we can bring together social and ecological systems to sustainably remake our cities and landscapes. Part monograph, part manual, part manife­sto, Toward an Urban Ecology reconceives urban landscape design as a form of activism, demonstrating how to move beyond familiar and increasingly outmoded ways of thinking about environmental, urban, and social issues as separate domains; and advocating for the synthesis of practice to create a truly urban ecology. 

In purely practical terms, SCAPE has already generated numerous tools and techniques that designers, policy makers, and communities can use to address some of the most pressing issues of our time, including the loss of biodiversity, the loss of social cohesion, and ecological degradation. Toward an Urban Ecology features numerous projects and select research from SCAPE, and conveys a range of strategies to engender a more resilient and inclusive built environment.

Native birds aren't crazy about exotic street tree plantings

"Urbanisation is a leading cause of biodiversity loss and habitat fragmentation internationally, and the conservation of representative native assemblages is a challenge confronting environmental managers in expanding urban landscapes. This study investigates the bird assemblages occurring in a rapidly growing regional centre, Ballarat, southeastern Australia. It aims to examine the relationships between urbanisation and bird communities in a regional city by investigating the differences in bird assemblage composition related to the type of vegetation (native or exotic) in urban streetscapes. Bird surveys were completed across four broad habitat types: remnant vegetation, exotic streetscapes, native streetscapes and newly developed streetscapes. Each habitat type had three 1 ha replicate sites. Results show that remnant vegetation fringing residential areas and native streetscapes supported around 60% more native bird species than exotic and newly developed streetscapes. Avian species composition was significantly different between broad habitat types, with remnant vegetation and native streetscapes maintaining representative native bird assemblages, but exotic streetscapes and newly developed streetscapes were dominated by introduced birds. Our results show that, for representative native bird assemblages to be maintained in urban areas, the maintenance of remnant and native vegetation is essential."

From:

Bringing the city to the country: relationships between streetscape vegetation type and bird assemblages in a major regional centre 

Brendan S Champness,  Grant C Palmer,  James A Fitzsimons

Journal of Urban Ecology, Volume 5, Issue 1, 2019, juz018, https://doi.org/10.1093/jue/juz018

Doug Tallamy on exotic invasive plants

"We have planted Kousa dogwood

(Cornus kousa), a species from China

that supports no insect herbivores,

instead of our native flowering

dogwood (Cornus florida) that supports

one hundred and seventeen species of

moths and butterflies alone. On

hundreds of thousands of acres we

have planted goldenraintree

(Koelreuteria paniculata) from China, a

tree that supports one caterpillar

species, instead of a variety of our

beautiful oaks, and we have lost the

chance to grow five hundred and

thirty-four species of caterpillars, all of

them nutritious bird food. My own

research has shown that native

ornamentals support twenty-nine times

more biodiversity than do alien

ornamentals. Further, it's unnerving to

learn that eighty-two percent of the

woody invasives in our country are

escapees of the horticultural industry."

reprinted from the Wild

Ones Journal Vol. 22, No. 2.

Urban Ecology: Science of Cities

"How does nature work in our human-created city, suburb, and exurb/peri-urb? Indeed how is ecology - including its urban water, soil, air, plant, and animal foundations - spatially entwined with this great human enterprise? And how can we improve urban areas for both nature and people? Urban Ecology: Science of Cities explores the entire urban area: from streets, lawns, and parks to riversides, sewer systems, and industrial sites. The book presents models, patterns, and examples from hundreds of cities worldwide. Numerous illustrations enrich the presentation. Cities are analyzed, not as ecologically bad or good, but as places with concentrated rather than dispersed people. Urban ecology principles, traditionally adapted from natural-area ecology, now increasingly emerge from the distinctive features of cities. Spatial patterns and flows, linking organisms, built structures, and the physical environment highlight a treasure chest of useful principles. This pioneering interdisciplinary book opens up frontiers of insight, as a valuable source and text for undergraduates, graduates, researchers, professionals, and others with a thirst for solutions to growing urban problems."

Request for submissions: New Forms of Urban Agriculture: An Urban Ecology Perspective

We invite you to make a contribution to a new book

Background and Purpose of the Book

The absence of reliable empirical data on the scale and impact of UA on urban resources is a serious gap in our understanding of the viability and sustainability of UA and may also explain urban planner’s reluctance to embrace the concept. The conception of UA as being necessarily integrated in urban systems has sparked attention from researchers for the multifunctionality and post-productive attitude of New Forms of Urban Agriculture (NFUA). The current volume intends to discuss the critical perspectives related to the actual and potential role of urban and peri urban agriculture in the developing and the developed world, where forms, adaptations, and debates around UA vary distinctively. See attached abstract for more detail.

Invitation for Chapters

The primary purpose of the book is to provide new empirical evidence evaluating, investigating and exploring urban agriculture using the perspective of urban ecology divided into five categories: land, water, waste, labor, and fauna.

An abstract of 150-200 words is due 31-October-2019. Approved contributors are expected to submit a full manuscript by 15-December-2019. Please send abstracts or any questions to akijac@nus.edu.sg.

Please feel free to recommend other contributors! Additional material and guidance is available on request. Warm regards and thanks.

Preadaptation leads to foreign conquest

“While most people have a negative view of spontaneous urban plants, they are actually performing many of the same ecological functions that native species perform in nonurban areas. ..absorbing excess nutrients that accumulate in wetlands; reducing heat buildup in heavily paved areas; controlling erosion along rivers and streams; mitigating soil, water, and air pollution; providing food and habitat for wildlife; and converting the carbon dioxide produced by the burning of fossil fuels into biomass.

The typical urban plant is well adapted to soils that are relatively fertile, dry, unshaded, and alkaline. Through a twist of evolutionary fate, many of these species have evolved life-history traits in their native habitats that are ‘pre-adapted’ them to flourish in cities.

Marble or brick buildings, for example, are analogous to naturally occurring limestone cliffs. Similarly, the increased use of deicing salts along walkways and highways has resulted in the development of high-pH microhabitats that are often colonized by either grassland species adapted to limestone soils or salt-loving plants from coastal habitats. Finally, the hotter, drier conditions one finds in cities favor species that come from exposed, sunny habitats in nature.

Preadaptation is a useful idea for understanding the emergent ecology of cities because it helps to explain that some plants and not others grow on piles of construction rubble, chain-link fence lines, highway median strips, pavement cracks, and compacted turf.

While most biologists view invasive plants as a serious biological problem, the fact remains that their initial introduction and distribution were usually the result of deliberate decisions that reflected the economic, ornamental, or conservation values of the day. Between the 1930s and the 1960s, various federal, state, and local agencies encouraged— and often subsidized— the cultivation of plants such as kudzu, multiflora rose, and autumn olive for erosion control and wildlife habitat purposes. It should come as no surprise that they became major problems forty years later, after millions of them had been planted. Indeed, the spread of nonnative species across the landscape is as much a cultural as a biological phenomenon, a fact often overlooked by advocates of strict ecological restoration.”  

--Peter Del Tredici

Bring Conservation Home

“The St. Louis Audubon Society envisions an ever-growing mosaic of native plant and animal landscapes across the St. Louis region, including even the smallest urban yard.  

Our Bring Conservation Home Program provides on-site assistance to small, private landowners in the greater St. Louis area for the restoration of native plant and animal habitat on their grounds. The Bring Conservation Home Program will offer advice in landscaping with environmentally healthy and sustainable native plant species, the removal of invasive plant species such as bush honeysuckle, water conservation on the urban landscape, and other stewardship practices that promote healthy habitat for birds, native wildlife and people.”

For more information visit http://www.stlouisaudubon.org/conservation/BCH/index.php

Yay Atlanta!!

In May 2018, the City of Atlanta launched its first urban ecology study. This effort will evaluate and inventory the City’s natural environs, including rivers and creeks, forest and tree canopy, ridges and watersheds, public and private green spaces, and other features that encompass and define the City’s existing landscape. The Urban Ecology Framework will identify what natural features are unique to the City of Atlanta, how ecosystems or habitats can be restored, and which policies promote development aligned with those features and systems. This inventory will be used to define a better future condition for the natural environment, including high-level recommendations about future green spaces, green connections, and green policies. This work represents the implementation of the Atlanta City Design value Nature, which aims to improve and accentuate Atlanta’s authentic character in a way that can accommodate a much larger population.

The Urban Ecology Framework (UEF) is being led by the Department of City Planning with involvement and cross-collaboration from other City Departments, such as Departments of Watershed Management and Parks and Recreation, as well as Partner organizations like Trees Atlanta and Park Pride. The consultant team, led by Biohabitats, Inc, is facilitating an ecological assessment to be followed by an evaluation of the Tree Preservation Ordinance (TPO).

Diversity increases ecosystem stability

Freiburg’s forestry scientists prove that forests that are more diverse are also more productive and more resilient

Freiburg, Sep 05, 2019

Forests with a large variety of species are more productive and stable under stress than monocultures: scientists from the University of Freiburg have confirmed this with data from the world’s oldest field trial on the diversity of tropical tree species. The team around PhD student Florian Schnabel has published its results in the journal Global Change Biology.

As the researchers state, there is increasing scientific evidence of positive relationships between the diversity of tree species and ecosystem functioning. However most studies on this relationship to date have used either data from forests where the influence of biodiversity cannot be separated from other factors, or from young planted experiments, which do not provide data on longer periods of time. Therefore, the Freiburg research team analyzed data from the Sardinilla experiment which was planted in Panama in 2001. This experiment covers 22 plots planted with one, two, three or five native tree species. Since these grow at different rates, the plots with a greater variety of species also have a greater structural diversity with regard to the height and diameter of the trees. Annual data on the size and height of the trees, which are seen as indicators of the productivity and stability of the ecosystem, come from the period 2006 to 2016.

The study concludes that mixtures of two and three tree species have on average a 25 to 30 per cent higher productivity than monocultures, and those with five species even 50 percent higher. The differences during a severe dry period caused by the tropical climate phenomenon El Niño were especially pronounced. This indicates that forests with a greater diversity of tree species are not only more productive, but also more stable and resilient under drought stress – the researchers believe this is a particularly important finding in view of global climate change. In the context of initiatives that aim to reduce atmospheric CO2 with extensive reforestation, these results indicate that to store the same amount of CO2 in biomass, far less space is needed with mixed-species forests.

According to the team, these results offer new insights into the dynamics of tropical plantation forests and emphasize the importance of analyses that cover a longer development period, since they contribute to a better understanding of the connections between the diversity, productivity and stability of ecosystems. The study is based on Florian Schnabel’s master thesis, for which he will be receiving the Hansjürg-Steinlin prize, a University of Freiburg award for new talent, in October at the start of the 2019/20 academic year. Florian Schnabel is now a PhD student involved in the TreeDì project at the German Centre for Integrative Biodiversity Research (iDiv) in Leipzig.

Plant recruitment in urban landscapes

Piana et al write in Frontiers in Ecology and the Environment (Aug 2019) that multiple drivers affect plant recruitment in the urban environment. From their analysis of available research--climate, biotic invasion, pollution, land cover change, and human activity all play pivotal roles. Their article is available at https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/fee.2098

Perspectives in Urban Ecology

(modified from Wu, 2008)

Diversified Management Expands Insect Biodiversity

Leston and Koper published in Journal of Urban Ecology (2019) their findings on their study of altering mowing regimes in urban rights-of-ways and their impacts on insect populations. They concluded that “to increase taller butterfly resources while still controlling weeds with urbn ROWs, we recommend reducing management frequency within the interior ROWs while maintaining frequent management along ROW borders that are adjacent to infrastructure.” This would reinforce landscape management recommendations of ‘cues to care’ on the outer edges to improve edge aesthetics of successional landscape approaches as well.

From ditches to bioswales

Zoe Myers, research associate at the University of Western Australian University, makes a compelling argument in her article "More than just drains: recreating living streams through the suburbs" that urban waterways deserve more than closely clipped lawns and ruderal weeds. Her research focuses on the benefits of converting traditional waterway management types to living stream corridors. She considers that this vast network of functional drainage systems could be opened to public use as a riparian park. Myers mentions that converting to bioswales would reduce urban heat islands, increase biodiversity, maximize aesthetics, and increase property values. Read more about it on The Conversation website at https://theconversation.com/more-than-just-drains-recreating-living-streams-through-the-suburbs-83345

The enemies hypothesis

The enemies hypothesis holds that predatory insects are more effective at controlling pests than mechanical or chemical control methods (Russell 1989). Parsons and Frank (2019) found evidence recently that by not including environments for predators around urban trees, pests can get out of control. They studied several hundred crape myrtle trees on the NC State campus and the types of environments that are around the trees, and found a positive correlation between crape myrtle pests and impervious cover (hardscape) within 100 meters of the trees. Diverse environments provide more opportunity for diverse beneficial controls.

Russell. 1990. Enemies Hypothesis: A review of the effect of vegetational diversity on predatory insects. Environmental Entomology 18(4).

Parsons, S. and Frank S. 2019. Urban tree pests and natural enemies respond to habitat at different spatial scales. Journal of Urban Ecology 5(1).

Us

Between the years 1970-2000, urban areas have expanded worldwide into natural or agricultural lands with an area about the size of Belgium (Goldblatt et al, 2018).

The Lessons of a Hideous Forest

Arborist William Bryant Logan wrote in the New York Times (July 20, 2019) about the rewilding of New York's Fresh Kills landfill from a recent visit. He reports on the surprising plant and animal biodiversity and of Nature's ever-present healing abilities. Read about it at https://www.nytimes.com/2019/07/20/opinion/sunday/forest-garbage-trees.html?smtyp=cur&smid=tw-nytimesscience

Bird compositions are changing from bird feeding

A recently published paper by Plummer et al in Nature (Nature communities 10) reveals that in a forty year study, urban bird populations are changing to feeder-oriented birds. So the birds on seed bags is actually an urban bird checklist!

Overcultivation reduces biodiversity

A study of 85 urban gardens in Zurich analyzed management intensity and resulting soil macro and microfauna. The researchers found that high garden management intensity declined plant diversity and soil fauna.  

From: Direct and indirect effects of urban gardening on aboveground and belowground diversity influencing soil multifunctionality

Simon Tresch, 

David Frey, 

Renée-Claire Le Bayon, 

Paul Mäder, 

Bernhard Stehle, 

Andreas Fliessbach & 

Marco Moretti 

Scientific Reports volume 9, Article number: 9769 (2019) 

The more you manage for invasive species control the faster the success

Johnson and Handel found through their study of parks in NYC that the level of management intensity is important to overall restoration success. See their study in Urban Forestry and Urban Greening at https://www.sciencedirect.com/science/article/pii/S1618866718306472

Urban Ecological Planning Guide for Santa Clara Valley

Here's a planning guide established for urban biodiversity for Santa Clara Valley, California.
https://www.sfei.org/sites/default/files/biblio_files/UrbanEcologicalPlanningGuide_Final_062019.pdf

Crevice Gardens

“But hang on to your prickly pears. I've discovered there is something even more adventurous than a rock garden, a more extreme version called a crevice garden.”

Read more: http://www.lowellsun.com/lifestyles/ci_32676040/crevice-gardens-urban-models-sustainability#ixzz5qSSZtenB

Don't light that pond!

“Light at night might be convenient for humans, but it's having a detrimental effect on amphibian populations, according to new research from Binghamton University, State University of New York.

"Research on the effects of light pollution has recently seen a surge in popularity," said Binghamton University Assistant Professor of Biological Sciences Jessica Hua. "It's difficult to find any place on Earth that is not affected by even minimal light pollution. We recognized a gap in the research and realized that not much was known about how light pollution can impact amphibians. Since amphibians are sensitive to environmental changes, they make great models for studying how pollution of any type can impact other species."

Hua, along with graduate student Grascen Shidemantle and undergraduate student Dyllan May, exposed wood frogs to a control and two anthropogenic light conditions: intensified daytime illuminance and artificial light at night (ALAN). They found that both the intensified daytime illuminance treatments and the ALAN treatment decreased hatching success in tadpoles. Tadpoles that were reared in the ALAN treatment, on the other hand, were larger, less active, more sensitive to road salt pollution and had more parasites.”

Earth Day 2019

Look up at the sky —
The heavens so blue, the sun so radiant,
The clouds so playful, the soaring raptors,
The meadows in bloom, the woodland creatures,
The rivers singing their way to the sea,
Wolf song on the land, whale song in the sea,
Celebration everywhere, wild, riotous,
Immense as a monsoon lifting an ocean of joy,
Spilling it down over the landscape,
Drenching us all with a deluge of delight
As we open our arms and rush toward each other,
You and I and all of us,

Moved by that vast compassionate Presence

That brings all things together in intimate Celebration,

Celebration that is the universe itself.

-adapted from “Every Being Has Rights” by Thomas Berry

Urban Forestry Toolkit

Vibrant Cities Lab (http://www.vibrantcitieslab.com/toolkit/) has produced a new urban forest toolkit for communities. Hosted by the U.S. Forest Service, American Forests and the National Association of Regional Councils, the Vibrant City Lab is an online resource for looking at the positive health impacts that urban forests have in communities. The website posts recent research on human health, economic development, water quality, air quality, public safety, and other urban issues. The urban forest toolkit walks citizens through an urban forestry process of assessing, prioritizing, organizing, building, planning and sustaining.

Bringing Nature to Neighborhoods and Advancing Urban Ecology

Bringing Nature to Neighborhoods and Advancing Urban Ecology

Attendees of the Greater and Greener Conference

07/22/2019

Description

"In this session, you'll hear how Portland, OR, is working at multiple scales to bring biodiversity back to the city and its neighborhoods. Portland Parks and Recreation's new ecologically sustainable landscapes program brings nature to neighborhood parks -- improving the ecological functions of park spaces while expanding local access to nature for urban residents. The program is adding nature patches to developed park landscapes that provide natural experiences for people and habitat for wildlife. Nature patches use a varied natural palette of native and flowering plants, logs, boulders, paths and fencing to retrofit parks with spaces that close the play gap and enhance ecological sustainability. These projects help create unique park landscapes intended to help to support native pollinators, reduce maintenance, provide education and exploration opportunities, and foster collaboration. Forest Park Conservancy is leading the Greater Forest Park Conservation Initiative, a public-private collaborative strategy to restore Forest Park and 10,000 acres surrounding the park. They partner with public agencies, non-profits, and individual land owners to restore critical wildlife habitat and recreational spaces. Attendees will learn about FPC's successes and the challenges they've navigated in this 20-year initiative. This session will look at the challenges and lessons learned by the Forest Park Conservancy (FPC) over the past five years leading the Greater Forest Park Conservation Initiative, a public/private collaborative strategy to restore Forest Park and 10,000 acres surrounding the park. We partner with public agencies, other nonprofits, and individual landowners to restore critical wildlife habitat and recreational spaces. Attendees will learn from FPC’s staff about successes and challenges we have navigated thus far in this 20-year initiative. We will lead a discussion about the next five years and a group conversation about restoring large remaining tracts of land in urban areas."

Location

Denver, CO

Instructors

Alejandro Orizola, Forest park Conservancy, Eric Rosewall, Portland Parks & Recreation, Dave Hutch, Vancouver Parks & Recreation.

Website Registration

https://www.greatergreener.org

The map of life

Map of Life is a global resource for biodiversity mapping and monitoring. A set of pre-released examples illustrate a new service that taps into a vast biodiversity data store and high-resolution habitat information to pinpoint suitable species locations in unprecedented detail. This allows a transparent, interactive assessment of species potential representation in reserves. The highlighted species flag the much diminished range size and large conservation gaps remaining, especially in habitat specialists.  Go to the Map of Life at https://species.mol.org/pa

Conducting urban ecology research on private property: advice for new urban ecologists

Conducting urban ecology research on private property: advice for new urban ecologists: Abstract. Private property makes up a large proportion of urban green space and differs from public green space in ecologically important ways. While including

Seasonal homogenization of bird species?

“Urbanization presents novel challenges to native species by altering both the biotic and abiotic environments. The rapid pace of declines in species diversity and ecosystem services makes generalizations imperative. Studies have attempted to make generalizations about how species with similar traits respond to urbanization, although the results of such studies are geographically idiosyncratic. Here, we present a comparative study in three US cities: Fresno, California; Tucson, Arizona; and Phoenix, Arizona in an attempt to examine consistency in how urbanization affects native bird assemblages. Using presence-absence data to define regional and urban species pools, we tested for whether the urban avian assemblage is a random subset of the regional avian assemblages on the basis of both traits and phylogeny, and whether or not urbanization causes biotic homogenization among avian assemblages. We found little evidence for non-random trait shifts, with only distributions of diet guild, migratory status, and main habitat showing any significant change, and no evidence for non-random phylogenetic patterns in urban avian assemblages. We did however find some evidence for neutral processes in species’ occupancy of urban habitats. Species in the urban species pools have a higher median reporting frequency than species in the regional species pools in all three cities, although this difference is statistically significant in only one city. Cluster analyses show that levels of biotic homogenization are more severe in spring than in winter. The results presented here indicate that while urban avian assemblage structure may be determined by species’ traits, which may possess phylogenetic signal, simple occurrence in an urban area is likely due to random or neutral processes. The seasonality of homogenization has not to our knowledge been previously reported. We propose that the largely similar results from the three cities in this study result from structural similarities in the matrix habitats, and that the nature of matrix habitat and context of urbanization needs to be considered in future studies in order to resolve existing inconsistencies.”

From:  Front. Ecol. Evol. | doi: 10.3389/fevo.2019.00071 

“Effects of Urbanization on Bird Species in Three Southwestern US Cities”

Hensley, Katti, Trisos, Warren, MacFarland, Blumenshine and Reece

Tallahatchie, Mississippi

Meridian, Mississippi

Grand challenges in urban ecology

Front. Ecol. Evol., 09 June 2015 | https://doi.org/10.3389/fevo.2015.00057

Grand challenges in urban ecology

Diane E. Pataki^*

Department of Biology, University of Utah, Salt Lake City, UT, USA

"The field of urban ecology has seen a major expansion in the last two decades. As the world rapidly urbanizes, human settlements constitute one of the few ecosystems on earth that are significantly increasing in their extent. As a result, interest from both the scientific community and society at large has turned its attention to the functioning of cities and their impacts on larger regions, global resources, and human well-being. Yet, urban ecosystems are fundamentally different from their natural counterparts in the dominant influence of human actions, both intentional and unintentional, on ecosystem function. While the term urban ecology is attributed to the Chicago School of sociology (Park et al., 1925), interdisciplinary, ecological studies of human settlements worldwide were facilitated most widely by UNESCO's Man and the Biosphere Program in the 1970's, and two decades later by the establishment of urban sites in the U.S. National Science Foundation's Long-Term Ecological Research Network (Sukopp, 2002; McDonnell, 2011; Formann, 2014). The resulting studies of urban-rural gradients, urban mass and energy budgets, and the “ecology of cities” have led to rapid development of methods and conceptual frameworks for integrating the social and natural sciences in the study of cities as ecosystems (Pickett et al., 2001; Alberti et al., 2003; Grimm and Redman, 2004; Moffett and Kohler, 2008; Chowdhury et al., 2011; McDonnell, 2011; Pataki et al., 2011a). While many early studies of urban ecosystem structure and function were case studies of individual cities and specific urban ecological processes, there are an increasing number of cross-city comparisons that are facilitating a new, synthetic understanding of the causes and consequences of urbanization and the complex interactions among urban ecosystem components (Loram et al., 2008; Kennedy et al., 2009; McDonnell et al., 2009; Chowdhury et al., 2011; Kendal et al., 2012; Jenerette et al., 2013; Ahern et al., 2014; Groffman et al., 2014).

While urban ecology is poised to make new breakthroughs in the functioning of complex, human-dominated ecosystems, the potential to translate scientific advances to practical applications has never been greater. Cities worldwide are struggling with a myriad of environmental and social problems as growing cities face air, water, and soil pollution, resource depletion, and aging infrastructure. As a result, there is renewed interest in developing and testing new solutions to these problems, with an increasing emphasis on approaches that apply ecological principles such as green infrastructure (Gill et al., 2007; Tzoulas et al., 2007), habitat preservation and connectivity (Rudd et al., 2002; Breuste, 2004; Goddard et al., 2010; Hostetler et al., 2011), urban metabolism (Newman, 1999; Kennedy et al., 2011; Pincetl et al., 2012; Shahrokni et al., 2015), and ecological footprints (Luck et al., 2001; Jin et al., 2009). Cities are increasingly the focus of biodiversity inventories (Hermy and Cornelis, 2000; Loram et al., 2008; Clarke et al., 2013), measurements of greenhouse gas concentrations and fluxes (Velasco and Roth, 2010; McKain et al., 2012), and monitoring of the performance of green roofs, bioswales, and other green infrastructure (Mazer et al., 2001; MacIvor et al., 2011; Lundholm et al., 2014). The challenge going forward will be to apply an increasingly advanced and nuanced understanding of urban ecology in the practice of planning, designing, and monitoring cities as dynamic ecosystems.

Such applications are a test of both the depth and breadth of our understanding of urban ecosystem processes. Unlike natural ecosystems, cities contain many ecosystem components that are almost entirely human-constructed. Building robust ecosystems that can withstand environmental change and avoid negative, unanticipated consequences of modifying the environment requires a systems-level understanding of ecosystem complexity, thresholds, and feedbacks (Lovell and Johnston, 2009; Ahern, 2013). In the built and engineered environment, natural and biotic processes that have generally been termed “ecosystem services” must be translated into specific design and performance elements and metrics at the appropriate scales if ecological approaches are to be successfully used to mitigate pollution, conserve biodiversity, improve human health, and enhance human well-being (Alberti, 2007; Oberndorfer et al., 2007; Syrbe and Walz, 2012; Ahern, 2013). Moving forward, urban ecologists face a new set of challenges as the field transitions into the next phase of understanding cities and human settlements from an ecological perspective. Here, I briefly summarize three of these grand challenges. This list is not exhaustive, but highlights some key impactful, emerging areas of current research in urban ecology.

Developing the Science of the Built Environment

Cities are often described as “novel” ecosystems which had no natural analog prior to the worldwide expansion of the urban population (Hobbs et al., 2006, 2009; Kowarik, 2011). Definitions of novel ecosystems and their implications are still debated (Seastedt et al., 2008; Higgs, 2012; Morse et al., 2014; Murcia et al., 2014); nevertheless, urban ecosystems contain a broad range of distinct microenvironments and biological assemblages, from remnant natural ecosystems to almost completely human built and constructed environments. While ecology has a century-long history of theorizing the processes that lead to the assembly and function of non human-dominated ecosystems, the extent to which such theories can be applied to designed and constructed ecosystems is still actively debated (Niemelä, 1999; Grimm et al., 2000; Kaye et al., 2006; Moffett and Kohler, 2008). The term “built” environment can refer to many different ecosystem components, some of which are analogs for natural ecosystems but with largely exotic flora and fauna and highly modified or imported soil materials (i.e., lawns and planted gardens). The built environment can also be dominated by abiotic components, i.e., concrete, asphalt, and other building materials. However, even largely abiotic environments have been shown to have a diverse microbial flora, with unknown impacts on larger scale ecosystem function or human health (Kembel et al., 2012; King, 2014; Konya and Scott, 2014).

We have made enormous progress in understanding the mechanisms underlying the structure and function of ecosystems in which humans play a small or indirect role. In urban ecology, a key next step is to gain an equally thorough understanding of constructed ecosystems. It's somewhat ironic that even though many components of urban ecosystems are built by humans, these constructed systems are often poorly understood from an ecological perspective. The factors that determine their biodiversity, community structure, and mass and energy cycles and flows can be quite uncertain, whether considering the ecology of ornamental gardens (Kareiva et al., 2007; Loram et al., 2008) or full accounting of matter and energy flows at varying scales (Moffett and Kohler, 2008; Kennedy et al., 2011; Pincetl et al., 2012). There is a particular need to consider the linkages among the built and biotic components of cities (Pickett and Cadenasso, 2008). Within the challenge of developing a new science of the built environment, specific questions include: what are the processes that lead to observed biological assembles and biodiversity in the built environment? How does ecosystem structure and function interact in the built environment? How does built ecosystem structure and function respond to environmental and social changes? It will be essential to fill in key data gaps in these areas going forward, and to use these data to develop robust conceptual and theoretical frameworks for understanding the ecology of built and constructed ecosystems.

The Urban Environment and Human Well-being

Cities are ostensibly built to enhance well-being. Both the built and non-built environments have numerous interconnections to well-being; the ecosystem services concept was developed specifically for this reason, as it asserts that “ecosystems are essential for human well-being through their provisioning, regulating, cultural, and supporting services” (Millennium Ecosystem Assessment, 2003). Yet, despite a growing literature on ecosystem services in both natural and urban systems, the precise nature of the relationship between many of the interacting processes categorized as ecosystem services and human well-being remains elusive at key spatial and temporal scales (Carpenter et al., 2009; Summers et al., 2012; Reyers et al., 2013), and this uncertainty is exacerbated in cities (van Kamp et al., 2003; Jorgensen and Gobster, 2010). Even when urban landscapes are constructed for specific purposes, such as recreation, beauty, and climate mitigation, their direct impacts on well-being often remain unknown (Cameron et al., 2012). This can be a matter of scale; carbon sequestration, for example, a commonly cited ecosystem service, directly affects quality of life only when its impacts occur on a large enough spatial scale to significantly affect atmospheric CO₂ concentrations and their role in the climate system (Pataki et al., 2006). Similarly, there may be time lags between provisioning or degradation of ecosystem services and their impacts on well-being (Raudsepp-Hearne et al., 2010). However, in the urban environment, the relationship between the many facets of human well-being and aspects of ecosystem structure and function are often uncertain, in part, because they have not yet been adequately studied in constructed ecosystems.

Thus, there are myriad studies showing that the presence of urban vegetation improves human health as quantified in several different ways, including accelerated recovery from stress and illness, increased physical activity, cognitive function, emotional health, and other metrics (Tzoulas et al., 2007; Lee and Maheswaran, 2011; Shanahan et al., 2015). However, the exact mechanisms underlying these relationships are still uncertain, and we do not yet know which aspects or types of vegetation provide the greatest benefits. Clarifying and contextualizing the relationships between aspects of well-being and specific facets of the urban environment is a key future challenge. Niemelä (2014) pointed out that the underlying mechanisms are likely to be inherently local; yet the answers to these questions are of interest worldwide. Sub-questions include: Are there greater physiological and psychological benefits of certain types of flora and fauna? Does it matter how many and which species are present? Does the configuration and size of parks and public greenspace vs. private gardens have a direct influence on well-being? Are there unanticipated consequences of reducing distributed and private greenspace in the urban core as cities grow denser, or can centralized public parks provide the same benefits? Intriguingly, there is evidence that perceptions of urban biodiversity are more aligned with well-being than actual biodiversity (Dallimer et al., 2012). Furthermore, there are many costs and potentially negative outcomes of replacing natural ecosystems with constructed ecosystems. Also called “ecosystem disservices,” these costs are generally under-studied, but include monetary costs, resource depletion, pollution, biodiversity loss, and negative health outcomes (Lyytimäki et al., 2008; Pataki et al., 2011b; von Döhren and Haase, 2015). This has led to the pervasive question: how can tradeoffs between various ecosystem services and disservices be optimized to lead to desired outcomes for human well-being? These questions require additional and more nuanced studies of human-environment interactions across cities, regions, and populations, as the answers are critical for translating urban ecosystem science into practice.

Ecology to Inform Urban Planning and Design

Given that the complex interactions among ecosystem components in the built environment are relatively poorly understood, and that there are still large uncertainties in the relationship between constructed ecosystems and human well-being, it is not surprising that urbanization has resulted in many unanticipated consequences. Cities are very complex ecosystems, and actions directed at one component of the system often have surprising effects on other components. The Millennium Ecosystem Assessment noted that actions meant to enhance one ecosystem service often lead to unintentional degradation of other services (Millennium Ecosystem Assessment, 2005). Similarly, many problems faced by modern cities are a consequence of previous attempts to improve urban environmental and social conditions. The combustion engine, the largest source of many types of urban air pollution, was seen a century ago as a solution to the public health problems presented by the horse and buggy (Nikiforuk, 2013). As cities move forward with new, proposed solutions to modern urban problems, even “green” solutions involving enhanced ecosystem services and green infrastructure may lead to unintended consequences when these technologies are implemented at large scales.

A closer association between urban ecology and the practice of planning, designing, and managing cities may avoid or mitigate some of these consequences. From a scientific perspective, a systems-level understanding of the functioning of cities is greatly enhanced by inclusion of stakeholders who are experts in the political, social, and policy dimensions of a given urban area. From a translational perspective, urban ecosystem science can be put into practice more rapidly when ecologists inform the planning process through the development and testing of sharing research questions, robust tools, and place-specific ecological data (James et al., 2009; Lovell and Taylor, 2013) as well as scientifically sound landscape and site designs (Felson and Pickett, 2005; Pickett and Cadenasso, 2008; Ahern, 2013; Felson et al., 2013a; Steiner, 2014). These activities are increasingly iterative and adaptive, with experimental science and ecological monitoring integrated with actions that can feedback to decision-making via participatory planning, adaptive management, and the coproduction of knowledge at the science-policy interface (Pickett et al., 2004; Pickett and Cadenasso, 2008; Lovell and Johnston, 2009; Evans, 2011; Felson et al., 2013b; Lovell and Taylor, 2013; Ahern et al., 2014; Niemelä, 2014). Such interactions take advantage of a shared understanding developed in the fields of both ecology and planning that cities are complex systems; that they are dynamic over space and time; and that they interact with their surroundings regionally and globally. Critically, the application of urban ecology into practice places a high bar on our understanding of ecology as a science, which must be robust enough to successfully design and maintain well-functioning, constructed ecosystems.

Conclusions

Many differences between urban ecology and the study of other types of ecosystems stem from the fact that urban ecosystems are intentionally created. And yet, they often function in surprising and unanticipated ways. Ecology is a systems science that is well-aligned with understanding urban complexity and the interacting components, feedbacks, and non-linear dynamics of cities. While a lack of integration between the fields of human and biological ecology limited the early development of urban ecological and theory and methods relative to other disciplines, there has been great recent progress in integrating urban social and biophysical science. Nevertheless, there are still limitations to translating these results into usable information for practitioners, as the urban ecological literature increasingly demonstrates that interactions among the human, non-human, and abiotic components of cities are highly place-, site-, and species-specific. The field faces new grand challenges as cities move toward large-scale implementation of actions, policies, and designs influenced by ecological concepts. It will be incumbent upon the scientific community to deliver rigorous urban ecological research in the forms of theoretical advances, model development and testing, well-designed experiments and monitoring, and close collaborations between scientists, practitioners, and stakeholders so that the “greener” cities of the twenty first century can be based on the best available science.”

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