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A National Assessment of Change in Green Infrastructure Using Mathematical Morphology
Citation:
WICKHAM, J. D. A National Assessment of Change in Green Infrastructure Using Mathematical Morphology. U.S. Environmental Protection Agency, Washington, DC, EPA/600/S-09/029, 2009.
Impact/Purpose:
The clients for our green infrastructure work include: 1) ORD Ecosystems Services Research Program, 2) EPA Region III, 3) Landscope, and 4) The Conservation Fund. Our national green infrastructure maps will constitute one element of the planned national atlas of ecosystem services. The national atlas of ecosystem services is a research project for the ORD Ecosystem Services Research Program. EPA Region III initiated development of a green infrastructure community of practice in 2009. The green infrastructure maps were delivered to EPA Region III colleagues. The principal investigator also gave an invited presentation on green infrastructure and landscape ecology at the EPA Region III Annual Regional Science Workshop (Annapolis, MD, February 2009). Landscope (http://www.landscope.org) is an online resource for the public and land-protection community that was developed by NatureServe and the National Geographic Society. Landscape is posting our green infrastructure products on their website. The Conservation Fund (http://www.conservationfund.org), a nongovernmental organization dedicated to advancing America's land and water legacy, became aware of our green infrastructure products through contact with Landscope, and they too have expressed interest in our work. An overview of our work was delivered electronically to The Conservation Fund.
Description:
Green infrastructure is a popular framework for conservation planning. The main elements of green infrastructure are hubs and links. Hubs tend to be large areas of natural vegetation and links tend to be linear features (e.g., streams) that connect hubs. Within the United States, green infrastructure projects can be characterized as: 1) reliant on classical geographic information system (GIS) techniques (e.g., overlay, buffering) for mapping; 2), mainly implemented by states and local jurisdictions, and; 3) static assessments that do not routinely incorporate information on land-cover change. We used morphological spatial pattern analysis (MSPA) as a complementary way to map green infrastructure, extend the geographic scope to the conterminous United States, and incorporate land-cover change information. MSPA applies a series of image processing routines to a raster land-cover map to identify hubs, links, and related structural classes of land cover. We identified approximately 4,000 large (> 100 hubs) networks within the conterminous United States, of which 10 percent crossed state boundaries. We also identified a net loss of up to 1.76 million ha of links and 1.72 million ha of hubs between 1992 and 2001. Our national assessment provides a backbone that states could use to coordinate their green infrastructure projects, and our incorporation of change illustrates the importance of land-cover dynamics for green infrastructure planning and assessment.