Landscape Dynamics in the Wildland–Urban Interface

The wildland–urban interface represents landscape change—changes brought about by urbanization, by shifts in forest management, and altered disturbance regimes, each having ecological, social, and economic ramifications. In this chapter, I will focus on some of the ecological ramifications associated with landscape change, primarily forest fragmentation and deforestation, resulting from urbanization. In particular, I will review forest fragmentation from a landscape and site perspective; examine the ecological aspects of edges, corridors, and roads; and discuss fragmentation in relation to human health issues as they pertain to the wildland–urban interface. Forest Fragmentation In 1967, MacArthur and Wilson (1967) published their seminal book on island biogeography. They proposed that the larger the oceanic island, the greater the species richness. Likewise, the closer an oceanic island is to the mainland, the greater the species richness. The application of island biogeographic theory to terrestrial systems (a forest fragment in a sea of forest management, agriculture or urban lands) has resulted in a plethora of research on forest fragmentation including several reviews (Forman, 1995; Laurance and Bierregaard, 1997; Lindenmayer and Fischer, 2006; Collinge, 2009). Forest fragmentation and loss are landscape processes. A review of the fragmentation literature, however, reveals a set of terms—such as habitat loss, habitat fragmentation, and habitat degradation—also being used to describe forest fragmentation. Following Lindenmayer and Fischer (2006), habitat refers to a particular set of environmental factors needed by a specific species. Thus, for this chapter, habitat fragmentation, loss, and degradation refer to the alteration or loss of suitable habitat for a specific species, whereas forest fragmentation, loss, and degradation refer to alteration of forest cover at the landscape and site level. This distinction is important. A forested landscape contains multiple habitats, and the modification of that landscape by human activities can affect the availability and spatial arrangements of those habitats and subsequently the species they contain differentially. Forman (1995) conceptualized human modification of forested landscapes into five processes: perforation, dissection, fragmentation, shrinkage, and attrition (Fig. 2–1). Overall, W.C. Zipperer, USDA Forest Service, P.O. Box 110806, Bldg. 164 Mowry Rd., Gainesville, FL 32611-0806 ([email protected]). doi:10.2136/2012.urban-rural.c2 Urban–Rural Interfaces: Linking People and Nature, David N. Laband, B. Graeme Lockaby, and Wayne Zipperer, editors Copyright © 2012. American Society of Agronomy, Soil Science Society of America, Crop Science Society of America 5585 Guilford Rd., Madison, WI 53711-5801, USA.