The role of urban centers in 21st century conservation

Background/Question/Methods

One goal of sustainability plans in urban environments is to maintain or improve biodiversity.  Biodiversity in this context is often poorly defined, but often assumed to focus on local diversity in remnant habitat and/or disturbed space. However, the substantial spatial disaggregation of the urban landscape created by variation in human valuation of land generates a complex template on which ecological communities respond.  We contend that basic ecological theory can and should be revised to understand how biodiversity is generated at multiple scales in urban ecosystems. The context for conservation and sustainability is that, in the built environment, how biodiversity is maintained is not completely understood without adequate understanding of how people value biodiversity within and among habitats, and how they interact directly and indirectly with the proliferation of preferred versus neglected species. 

Results/Conclusions

A detailed analysis of 113 woody plant communities in Baltimore, Maryland that include not just remnant and disturbed habitat but also those located on residential lots, commercial lots, parks and vacant lots, revealed significant variation in local diversity.  More interestingly, these communities exhibited high variation in species turnover (i.e., beta diversity) among land use types. High rates of species turnover can be attributed to many ecological mechanisms, such as differential dispersal, environmental gradients, and local interspecific interactions.  However, in the built environment, the high variation observed here among landuse types suggests a strong human role. If maintaining biodiversity in the built environment is to be a goal in conservation and sustainability plans, then incorporating the human dimension into the mechanisms that both maintain diversity locally and generate it between habitats will be necessary to understand.