COS 70-1
Homogenization of plant diversity in six major USA cites: Integrating socio-economic, environmental, and phylogenetic information

Wednesday, August 13, 2014: 8:00 AM
315, Sacramento Convention Center
William D. Pearse, Ecology, Evolution and Behaviour, University of Minnesota
J. Cavender-Bares, Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN
Sarah E. Hobbie, Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, MN
Neil D. Bettez, Cary Institute of Ecosystem Studies, Millbrook
Lindsay Darling, Program in Biological Sciences, Northwestern University, Evanston, IL
Christopher Neill, Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA
Peter M. Groffman, Cary Institute of Ecosystem Studies, Millbrook, NY
Sharon Hall, School of Life Sciences, Arizona State University, Tempe, AZ
James B. Heffernan, Nicholas School of the Environment, Duke University, Durham, NC
Kelli L. Larson, Schools of Geographical Sciences and Urban Planning/Sustainability, Arizona State University, Tempe, AZ
Jennifer L. Morse, Department of Environmental Science and Management, Portland State University, Portland, OR
Kristen C. Nelson, Departments of Forest Resources and Fisheries, Wildlife, and Conservation Biology, University of Minnesota, St. Paul, MN
J. O'Neil-Dunne, Spatial Analysis Lab, Rubenstein School of Environment and Natural Resources, University of Vermont
Diane E. Pataki, Department of Biology, University of Utah, Salt Lake City, UT
Colin Polsky, Geography, Clark University, Worcester, MA
R. Roy Chowdhury, Department of Geography, Indiana University
Meredith K. Steele, Department of Crop and Soil Environmental Sciences, Virginia Tech, Blacksburg, VA

As urban areas continue to expand both regionally and globally in the coming decades, so too will the area of urban plant habitat. While cities are often relatively species-rich, it is widely considered that urban plant assemblages are novel ecosystems that do not resemble the natural species pool. This may, in part, result from the unusually intimate association between human preferences and the composition of urban plant assemblages, as well as the unusual abiotic conditions within cities. We present results from systematic surveys of the urban flora (representing more than 3000 different plant species) in household yards from six major cities across the continental US: Baltimore, Boston, Los Angeles, Miami, Phoenix, and Minneapolis-St Paul. These plant surveys are combined with detailed interviews and questionnaires about landowners' preferences and socio-economic background, alongside a novel species phylogeny, species' functional traits, and environmental data. We use these data to determine the major drivers of plant assembly in our study sites.


While each city contains unique species, the phylogenetic and functional trait diversity of each city is similar and highly overlapping. This suggests that while cities may contain a distinct and diverse set of species, their diversity represents an evolutionarily and functionally biased subset of the total regional species pool that is consistently promoted and selected by humans in the urban environment. This bias is particularly apparent with regard to the 'neat lawn' aesthetic, where landowners value a classic green, grassy space over other aspects of biodiversity. Where there is a mismatch between homeowners' intentions for their yards and the species composition of the yards themselves, we link this to the influence of environmental conditions and the wider biogeographical context of cities.