Landscape and Urban Planning 101 (2011) 215–227 Contents lists available at ScienceDirect Landscape and Urban Planning journal homepage: www.elsevier.com/locate/landurbplan A multi-scale assessment of local and contextual threats to existing and potential U.S. protected areas Alisa A. Wade a,∗ , David M. Theobald b,c , Melinda J. Laituri d a National Center for Ecological Analysis and Synthesis, 735 State Street, Suite 300, Santa Barbara, CA 93101, United States b Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO 80523-1474, United States c Natural Resource Ecology Lab, Colorado State University, Fort Collins, CO 80523-1499, United States d Department of Forest, Range, and Watershed Stewardship, Colorado State University, CO 80523-1472, United States article info Article history: Received 14 May 2009 Received in revised form 4 February 2011 Accepted 12 February 2011 Available online 12 March 2011 Keywords: Protected areas Conservation planning Threats assessment Multi-scale analysis abstract Assessing threats to protected areas is a critical step to ensure effective resource conservation and to lever- age future conservation actions. It is equally important to assess external and internal threats because human activities both in and around a protected area can impair the area’s ecological goals or impart important ecological benefits to adjacent lands. We applied a threat framework that accounts for both local and surrounding threats to identify areas in the conterminous United States that provide or offer opportunities for ecological conservation. We find that, of the lands that are least threatened locally, 49% have some existing formal protection, but that more than 35% of the existing protected portfolio is at risk from external threats. However, over 20% of currently unprotected lands provide potential opportunities for conservation. Of the area identified with highest potential conservation opportunities, over 50% is on private lands, highlighting the need to engage owners of private land in conservation. There is greater potential for large, buffered, core conservation areas in the West, but other areas require networks of stepping-stone conservation islands. We summarize our results by ecoregions and within 40 national parks, identifying areas that are notably unthreatened (Colorado Plateau and Northwestern Glaciated Plains ecoregions and Great Basin and Canyonlands parks) versus those that may require more intense management actions (Eastern Great Lakes and Hudson Lowlands and Southeastern Wisconsin Till Plains ecoregions and Cuyahoga Valley and Great Smoky Mountains parks). Finally, we discuss how the approach could be applied and improved for finer-grained, local assessments. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Lands that are protected with formal, permanent protection from conversion of natural land cover and managed in whole or in part for conservation purposes (Jennings, 2000) provide valuable ecosystem services and habitat (Millennium Ecosystem Assessment, 2003; UNEP, 2003) and serve as critical leverage points for future conservation actions (Margules and Pressey, 2000). The current system of protected areas is important but not sufficient for biodiversity protection (Andelman and Willig, 2003; Newmark, 1985). Maintenance of natural processes within protected areas often relies on the existence of surrounding “buffer” lands (Hansen and Rotella, 2002; Wiens et al., 2002; Williams et al., 2005). Alterna- tively, human activities in the surrounding landscape may threaten ∗ Corresponding author. Current address: Department of Geosciences, University of Montana, Missoula, MT 59812-1296, United States. Tel.: +1 4065299722. E-mail addresses: alisaww@gmail.com (A.A. Wade), davet@warnercnr.colostate.edu (D.M. Theobald), mell@warnercnr.colostate.edu (M.J. Laituri). the protected area by effectively reducing its size, disrupting eco- logical flows, removing crucial habitat outside of the protected area, and increasing human disturbance at the boundary edge (Hansen and DeFries, 2007; Noss and Harris, 1986; Parks and Harcourt, 2002). Further, future conservation options may be limited by threats from the surrounding landscape (Cole and Landres, 1996; McDonald et al., 2008; USGAO, 1994). Assessing the number and intensity of threats to an area is recognized as a critical component in measuring protected area effectiveness (Ervin, 2003; Hockings, 2003; Margules and Pressey, 2000; Parrish et al., 2003; Salafsky and Margoluis, 1999) and in conservation prioritization frameworks (e.g., Abbitt et al., 2000; Murdoch et al., 2007; Wilson et al., 2006). Here, we define threats as human activities that may cause the destruction or impairment of ecological resources or processes (after Salafsky et al., 2008), and we ground our discussion of threats on a comprehensive list of threats to protected areas, the Conservation Measures Partnership, devel- oped by a consortium of non-governmental organizations, led by the International Union for Conservation of Nature (IUCN, 2006; Table 1). 0169-2046/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.landurbplan.2011.02.027