Appendix B. A table describing the criteria used to delineate protected-area centered ecosystems and the ecological mechanisms on which they are based, and a table summarizing the known impacts of land-use changes on ecological processes.
TABLE B1. Criteria used to delineate protected-area-centered ecosystem boundaries and the ecological mechanisms on which they are based. The mechanisms are means by which human activities on surrounding lands may alter ecological processes and/or the viability of native species within protected areas as described by Hansen and DeFries (2007).
| Mechanism | Ecological Effects | PACE Delineation criterion |
PACE data used in this study |
|
Change in ecological flows into and out of protected area |
Water, sediment, nutrients, and organisms move with water flows through watersheds. Land use in upper watersheds may alter these flows into protected area. |
Watershed boundaries: subbasins, watersheds, or subwatersheds intersecting protected area. |
8, 10, and 12-digit HUCs intersecting protected area (USDA-NRCS 2008) |
|
Disturbances (e.g. fire) may originate outside and move through a protected area. The condition of the disturbance initiation zone influences the likelihood of disturbance moving into the protected area. Both the disturbance initiation and runout zones may provide important habitat for organisms in the protected area. |
Perimeter around protected area of potential disturbance initiation and runout zones based on historic disturbance size and shape. |
None | |
|
Loss of crucial habitats |
Seasonal habitats, population source areas, movement paths, or portions of large home ranges for populations within protected areas may lie outside the protected areas. Land use may alter or destroy these crucial habitats. |
Migration, source-sink, and seasonal habitats of protected-area based organisms. |
None |
|
Change in effective size of reserve |
Species within a protected area can be lost due to isolation as the area of surrounding habitats is reduced due to land use. |
Habitat types in proportional representation up to size specified from species-area relationship. |
LANDFIRE Existing Vegetation Type layer (U.S. Department of Interior 2008) |
|
Human edge effects |
Human presence on the periphery of protected areas may cause changes in ecosystem processes and biodiversity that extend varying distances into the protected area (e.g., hunting, poaching, outdoor recreation, pet effects on wildlife, exotic species). |
Private lands within 25-km buffer around protected area. |
All private, non-protected land within 25 km buffer (Theobald unpubl. data) |
TABLE B2. Known impacts of land-use changes on ecological systems.
| Variable | Reason for inclusion/effects | References |
|
Land ownership |
Amount of public land influences the intactness of the larger ecosystem depending on the level of protection; amount of private land determines the potential for agriculture or other human development; private land is susceptible to extractive resource markets such as timber and amenity driven markets such as housing |
Turner et al. 1996 |
|
Population density |
Strongly correlated with adverse effects on species survival due to: poaching, disease spread and competition from pets or livestock, increases in exotic species, increases in human-wildlife conflicts, and loss of habitat from preferential human settlement patterns |
Kerr and Currie 1995, Brashares et al. 2001, Parks and Harcourt 2002, Revilla et al. 2001, Packer et al. 1999, Young et al. 2005, McKinney 2001, Newmark et al. 1994, Hansen and Rotella 2002 |
|
Housing density |
Recent, rapid increases in housing both at urban fringes and in rural settings, with particularly high rates around protected areas; highly correlated with aspects of ecosystem function and biodiversity; effects include: reduction in the overall size of the effective ecosystem, intensification of edge effects, interruption of linkages between habitats used as dispersal or migration routes, introduction of exotic species, and disruption of flows of energy and disturbance events; associated with new roads, potentially harmful pets, recreation, and wildlife-human conflicts |
Theobald 2001, Brown et al. 2005, Wade and Theobald 2010, Radeloff et al 2010, Hansen et al. 2005, Hansen and DeFries 2007, Crooks and Soule 1999, Boyle and Samson 1985 |
|
Land in agriculture |
Loss of natural habitat; creates barriers to movement of native species; creates population sinks along borders of protected areas; increases spread of invasive plant species; reduces water and air quality due to pesticides and fertilizers; conversion of former agricultural land to low density housing may change the available forage for some species and create more severe barriers to organism movement |
Sinclair et al. 2002, Pauchard and Alaback 2004, Kramer and Doran 2010 |
|
Impervious surfaces |
Expected to double by 2030; measure of water quality; protected areas located lower in a watershed are dependent on water quality and quantity from upstream |
Allan 2004, Jantz et al. 2005, Theobald et al. 2009 |
|
Area of roads |
Direct mortality to organisms; barriers to species movements; fragmentation of habitat; noise; spread of invasive and non-native species |
Forman and Alexander 2000, Ament et al. 2008 |
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