Landscape Patterns
Urban landscape patterns are emergent, coupled human-natural phenomena that epitomize the complexity of interactions and feedback mechanisms between human decisions and ecological processes (Figure 1, Alberti 2008). 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.
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RGI2: Landscape Composition and Configuration at the Basin and Sub-Basin Level in Western Washington
Marina Alberti (PI), Daniele Spirandelli
The goal of this research is to test selected landscape metrics as appropriate measures to assess land cover change in Western Washington over the last decade (1991-2001). Appropriate metrics are used as land cover indicators for monitoring basin and sub-basin scale land cover patterns and trends. We measure and test landscape composition (e.g., percent paved land or forest cover), landscape configuration (e.g., level of clustered development or forest fragmentation), and land use intensity (impervious surfaces and population density). We quantify the sensitivity of these metrics to the changes in land cover that have occurred in western Washington from 1991 to 2001 to assess their usefulness as regional land cover change indicators. With the completion of this project, relevant land cover indicators and maps will be provided to the Washington Department of Ecology for publication as part of a web-based Coastal Atlas mapping program. The results of this research will assist planners and policy makers to foster environmentally responsible land uses through greater understanding of regional landscape patterns and trends at the watershed and sub-basin scales.
Funded by: Environmental Protection Agency
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CTED Landscape Benchmarks Project
Marina Alberti (PI), Jeff Hepinstall, Michal Russo, Bekkah Coburn
This study develops and applies a set of landscape metrics as benchmarks for monitoring landscape changes associated with urban growth in central Puget Sound over the period 1991-1999. Selected metrics are examined and proposed as benchmarks for monitoring the effectiveness of the Washington State Growth Management Act and the progress towards its goals. Landscape metrics were selected among a large set of metrics developed in the field of Landscape Ecology to quantify and monitor landscape patterns. The study is based on a multi-year land cover classification and analysis of USGS Landsat Thematic Mapper (TM) at a three time-steps (1991, 1995, and 1999) at the regional and county level within and outside the urban growth boundary. A multi-scale resolution analysis is also conducted using 150 meter, 450 meter, and 750 meter moving windows across the region and to evaluate whether changing spatial scale has an impact on the results of the Aggregation Index, the Percentage of Like Adjacencies Index, and the Percentage of Land Index. A comparison of results before 1995 and after 1995, as well as inside and outside the GMA will help to evaluate the drivers of urban growth and the impact of the GMA.
Full Project Description >>
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Detecting Ecological Signatures of Development Patterns
Marina Alberti (PI), Stefan Coe, Daniele Spirandelli, Yan Jiang
We propose that distinct ecological signatures can be identified for urban development patterns, using landscape characteristics relevant to various ecosystem processes. We apply several landscape metrics to characterize the landscape composition and configuration of each development type. We hypothesize that land development types can be discriminated using several landscape metrics including percent land cover (i.e. impervious surface, forest, and grass), mean patch size, contagion, edge-to-interior ratio, and Shannon index. Using discriminant function analysis (DFA), landscape metrics are tested to assess their ability to discriminate between these different types of development. Ecological signatures provide a powerful tool for understanding interactions between human and ecological processes in urbanizing landscapes and for developing strategies to minimize ecological impacts of urban growth.
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The Impact of Urban Patterns on Aquatic Ecosystems: An Empirical Analysis in Puget Lowland Sub-Basins
Marina Alberti (PI),Derek Booth, Kristina Hill, Bekkah Coburn, Christina Avolio, Stefan Coe, Daniele Spirandelli
Landscape change associated with urbanization poses major challenges to aquatic ecosystems. Extensive studies have shown that the composition of land cover within a watershed can account for much of the variability in water quality and stream ecological conditions. While several studies have addressed the relationship between watershed urbanization and biotic integrity in streams, few have directly addressed the question of how urban patterns influence ecological conditions. These studies typically correlate changes in ecological conditions with simple aggregated measures of urbanization (e.g., human population density or percent impervious surface). We develop an empirical study of the impact of urban development patterns on stream ecological conditions in forty-two sub-basins in the Puget Sound lowland region on a gradient of urbanization. We hypothesize that ecological conditions in urbanizing landscapes are influenced through biophysical changes by four urban pattern variables: land use intensity, land cover composition, landscape configuration, and connectivity of the impervious area. Using community measures of benthic macroinvertebrates as indicators of in-stream biotic integrity we examined the relationships between urban development patterns and ecological conditions in these basins. Significant statistical relationships were found between landscape patterns—both amount and configuration of impervious area and forest land—and biotic integrity of streams suggesting that patterns of urban development matter to aquatic ecosystems.
Funded by: National Science Foundation
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