Tara L.E. Trammell

Ecosystem services in managing residential landscapes: priorities, value dimensions, and cross-regional patterns

Although ecosystem services have been intensively examined in certain domains (e.g., forests and wetlands), little research has assessed ecosystem services for the most dominant landscape type in urban ecosystems—namely, residential yards. In this paper, we report findings of a cross-site survey of homeowners in six U.S. cities to 1) examine how residents subjectively value various ecosystem services, 2) explore distinctive dimensions of those values, and 3) test the urban homogenization hypothesis. This hypothesis posits that urbanization leads to similarities in the social-ecological dynamics across cities in diverse biomes. By extension, the thesis suggests that residents’ ecosystem service priorities for residential landscapes will be similar regardless of whether residents live in the humid East or the arid West, or the warm South or the cold North. Results underscored that cultural services were of utmost importance, particularly anthropocentric values including aesthetics, low-maintenance, and personal enjoyment. Using factor analyses, distinctive dimensions of residents’ values were found to partially align with the Millennium Ecosystem Assessment’s categories (provisioning, regulating, supporting, and cultural). Finally, residents’ ecosystem service priorities exhibited significant homogenization across regions. In particular, the traditional lawn aesthetic (neat, green, weed-free yards) was similarly important across residents of diverse U.S. cities. Only a few exceptions were found across different environmental and social contexts; for example, cooling effects were more important in the warm South, where residents also valued aesthetics more than those in the North, where low-maintenance yards were a greater priority.

Ecological homogenization of residential macrosystems

Similarities in planning, development and culture within urban areas may lead to the convergence of ecological processes on continental scales. Transdisciplinary, multi-scale research is now needed to understand and predict the impact of human-dominated landscapes on ecosystem structure and function.

Ecological homogenisation in North American urban yards: vegetation diversity, composition, and structure

Urban ecosystems are widely hypothesised 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 thus evaluate the homogenisation hypothesis by comparing cultivated and spontaneously occurring urban vegetation to natural area vegetation across seven major US cities. Urban yards were homogenised across cities in terms of their diversity, composition, and structure. First, cultivated and spontaneous yard flora had higher numbers of species than did natural areas but similar phylogenetic diversity, indicating that yard species were drawn from a relatively small number of lineages. Second, yards were compositionally more similar across regions than were natural areas. Finally, vegetation structure, specifically cultivated tree density, was less variable in yards than natural areas across cities. Biodiversity homogenisation likely reflects similar horticultural source pools, homeowner preferences, management practices, and environmental filters across US cities.