The Natural Cities Project - A Method of Rapid Ecological Assessment for Urban Green Space

摘要

The Natural Cities Project is a collaborative effort to develop an understanding of urban ecosystems and to create a national model for the evaluation and preservation of ecological communities in urban settings. This project combines scientific evaluation of the ecological value of various urban sites, Community value of each site, and legal assessment of protection status or potential, to prioritize conservation efforts. This procedure ensures effective use of limited resources to protect ecologically and socially significant green space, thus increasing quality of life in the urban environment. The ecological component of this Project involved the development of a rapid ecological assessment method to rank the ecological value of urban sites, and we present our methods and results here. For the typical ecologist, significant adjustments must be made when considering urban sites. Urban environments contain many small, degraded sites that typically exhibit major signs of anthropogenic disturbance. These urban sites may be insignificant were they in a rural setting, but they can provide important ecological and social functions in urban environments. We have developed a simple survey method that can be done by individuals with minimal training to evaluate the ecological function and restoration potential of urban sites. This protocol emphasizes plot size, biodiversity, connectivity, and magnitude of alterations. The presence of impermeable surfaces, refuse, and particularly invasive exotic species are considered to be significant negative indicators for a site, while the presence of breeding birds, developed soils, high plant diversity, and connectivity with other sites are considered to be positive indicators. With the exception of four highly invasive species, exotics were considered to have biodiversity value equal to native species. This was done in recognition that urban ecosystems will never mimic native setting, and that exotic species contribute to ecological function and social value in urban settings. It is our hope that this method will be widely applicable to all urban sites.