Friday, May 13, 2011

Cosmopolitan Communities

In my research on marginal nature, I was surprised to find such strong cultural influences on the perceptions of urban ecologists about the value of wasteland habitats.  Cultural influences are found in differences in attitudes and practices between European and American urban ecologists. One finding of urban ecology has been that the ecosystems of cities of similar temperate regions of the world share species, and, perhaps, their plant communities are evolving as a generalized temperate urban plant community. In America, this homogenization of species is seen as something which must be stopped and native species must be defended against foreign invaders. 

Urban ecology in Europe is more accepting of these unique population dynamics of urban ecosystems. For them, the given conditions of urban ecosystems are that species composition is very dynamic and that global connectivity is a defining feature of that dynamic community. Although European urban ecologists take invasive species seriously, they are more accepting of introduced species as part of the long history of cosmopolitan mixing. From this perspective, non-native species additions to biodiversity in urban ecosystems, and so the European view of urban ecosystems is that, “although wild and rather specialist species may be missing, cities are great havens for biodiversity, in terms of both ecology and species, even in industrial areas.” (Bradshaw 2002) This contrasts with the views of many American urban ecologists, who generally insist that urban growth “replaces the native species that are lost with widespread “weedy” nonnative species (and) this replacement constitutes the process of biotic homogenization that threatens to reduce the biological uniqueness of local ecosystems.” (McKinney 2003)

Urban wastelands have been studied in both European and American cities, but, where European ecologists celebrate wasteland species diversity, American ecologists describe them as degraded habitat. From the American perspective, wastelands are the weedlands and biological slums from which invasions are launched on remnants of first nature. European urban ecologists have shown more interest and have had more opportunity to study urban “wasteland” sites due to the urban destruction left after World War II, and this research dating to the late 1940s has fostered more openness to species introductions as inevitable results of an urbanizing world. Sukopp observed of Berlin that wasteland sites are,

"…the field laboratories where possibly new and well-adapted ecotypes of our native or naturalized wild plants will originate in the changed environmental conditions. Ecosystems which have developed in urban conditions may be the prevailing ecosystems of the future. Many of the most resistant plants in our industrial areas and in cities do not originate from Central Europe, but are non-natives." (Sukopp 1979)

His openness to engaging the unique conditions of urban ecosystems (and wasteland sites in particular) without resorting to qualitative comparisons with lost native ecosystems is reflected in his rhetoric and his practice of urban ecology. Sukopp does invoke a cultural perspective on wasteland plant communities, but, rather than bemoan the lost of homeland purity like American ecologists do, he suggests that this dynamic mixture of native and non-native species evokes the social mission of urban settlements, and so he characterizes them as “cosmopolitan communities.”

More on Berlin and Sukopp's biodiversity work 

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