Homogenization of plant diversity, composition, and structure in North American urban yards


Urban ecosystems are widely hypothesized to be more ecologically homogeneous than natural ecosystems. We argue that urban plant communities assemble from a complex mix of horticultural and regional species pools, and evaluate the homogenization hypothesis by comparing cultivated and spontaneously occurring urban vegetation to natural area vegetation across seven major U.S. cities. There was limited support for homogenization of urban diversity, as the cultivated and spontaneous yard flora had greater numbers of species than natural areas, and cultivated phylogenetic diversity was also greater. However, urban yards showed evidence of homogenization of composition and structure. Yards were compositionally more similar across regions than were natural areas, and tree density was less variable in yards than in comparable natural areas. This homogenization of biodiversity likely reflects similar horticultural source pools, homeowner preferences, and management practices across U.S. cities.

Publication Type
Journal Article
William D. Pearse
Jeannine Cavender-Bares, University of Minnesota
Sarah E. Hobbie
Neil Bettez
Rinku Roy Chowdhury, Clark University
Lindsay E. Darling
Peter M. Groffman
Sharon J. Hall
James B. Heffernan
Jennifer Learned
Christopher Neill
Kristen C. Nelson
Diane E. Pataki
Benjamin L. Ruddell
Meredith K. Steele
Tara L.E. Trammell