Investigators: Marina Alberti, Daniele Spirandelli
Urban landscape patterns are emergent, coupled human-natural phenomena that epitomize the complexity of interactions and feedback mechanisms between human decisions and ecological processes.The process of urbanization results in a complex pattern of intermixed high- and low-density built-up areas and fragmented natural patches. Alternative urban development patterns affect ecological processes both directly—by replacing native habitat with simplified, human-dominated systems—and indirectly—by rearranging the biophysical attributes that cause a variety of interrelated local and global effects. By studying the Seattle and Phoenix metropolitan areas, Dr. Alberti and colleagues from the University of Washington and Arizona State University have started to document distinct ecological signatures of urban landscape patterns, using landscape characteristics relevant to various ecosystem processes. To test formal hypotheses about the mechanisms that link urban landscape patterns to ecosystem dynamics, they have started to empirically quantify and discriminate patterns of urban landscapes associated with a series of biophysical and socio-economic variable across a gradient of urbanization. The landscape signatures of development patterns are quantified using selected landscape-pattern metrics that describe four dimensions of landscape pattern that have been found significant to predict ecosystem function: form, density, heterogeneity, and connectivity. The research team has developed a high resolution data base that combines satellite imagery time series and land use parcel to characterize and model land cover change. They also use the Normalized Difference Vegetation Index (NDVI) to assess the impact of urbanization patterns on primary productivity and forest function. The effect of landscape change on human function is estimated using the price effects of forest cover on residential real estate.
Alberti, M. 2007. Ecological signatures: The science of sustainable urban forms. Places. 19(3): 56-60.