The Southern Megalopolis: Using the Past to Predict the Future of Urban Sprawl in the Southeast U.S

Abstract

The future health of ecosystems is arguably as dependent on urban sprawl as it is on human-caused climatic warming. Urban sprawl strongly impacts the urban ecosystems it creates and the natural and agro-ecosystems that it displaces and fragments. Here, we project urban sprawl changes for the next 50 years for the fast-growing Southeast U.S. Previous studies have focused on modeling population density, but the urban extent is arguably as important as population density per se in terms of its ecological and conservation impacts. We develop simulations using the SLEUTH urban growth model that complement population-driven models but focus on spatial pattern and extent. To better capture the reach of low-density suburban development, we extend the capabilities of SLEUTH by incorporating street-network information. Our simulations point to a future in which the extent of urbanization in the Southeast is projected to increase by 101% to 192%. Our results highlight areas where ecosystem fragmentation is likely, and serve as a benchmark to explore the challenging tradeoffs between ecosystem health, economic growth and cultural desires.

Application of a coupled human natural system framework to organize and frame challenges and opportunities for biodiversity conservation on private lands.

“…Land use change in the western Carolinas is driven by a growing population and urban development (Terando et al 2014) and a demand for woody biofuels (Johansson and Azar 2007). In the Blue Ridge ecoregion, high-elevation development is responsible for loss of habitat, particularly because good habitat is also desirable for homes with a view.…”

“…Likewise, suburban development in the Piedmont ecoregion of South Carolina is driving forest loss and land use change. This latter ecoregion falls within the center of the rapidly developing Southern Megalopolis (Terando et al 2014) where population is expected to increase by over 100% by 2050, resulting in greater urban development and continued stress on existing forest patches. Because of these increasing pressures on the land, and limited resources of county, state, and federal landholders, tools are needed for planning beyond the actions of government and particularly ones that involve private landowners.…”

“…The natural systems of our case studies have shifted rapidly, but conservation priorities, actions, or perceptions may reflect legacy rather than reality. For instance, although temperate forests of the southeast United States were replaced by agriculture during the 20th century, today forested landscapes are being lost to rapid urbanization, a more recent threat (Terando et al 2014). Likewise, decisions made during the late 1800s to convert native prairie to cropland across the Midwest, shifting it from a grassland biome or wild anthrome with low levels of human populations and land cover change to a cropland anthrome with little native habitat (Ellis et al 2010), dictate the scope of current conservation options on private land in the Midwest .…”

Human Appropriation of Net Primary Production (HANPP) in an Agriculturally-Dominated Watershed, Southeastern USA

“…The land use history of the watershed over the last 200 years is best characterized as agricultural. However, in the past two decades, land use and land cover change in the watershed is emblematic of rapidly expanding urban areas [47] and stable or declining forest cover [48] and farmland [49,50] across the southeast United States. Farmland abandonment has been partially in response to degradation of the local ultisols, primarily by topsoil erosion (e.g., [51]).…”

“…The remaining farmland is dominated by pasture based operations [52]. Urbanization in the ecoregion is driven by a population increase 40% larger than other areas in the United States [47].…”