Background/Question/Methods Landscape conservation strategies emphasize the protection of ecosystems covering large expanses of undeveloped land. Typically such landscapes include protected areas such as national parks or government-designated wilderness at their core, along with a surrounding matrix of public and private lands managed for multiple uses. Over time, differing landholder priorities and management approaches may result in discernible ecological differences between adjoining jurisdictions, leading to fragmentation within the larger ecosystem and the emergence of anthropogenic ecotones. Such differences may be obvious, as when a clearcut timber harvest adjoins one side of a jurisdictional boundary, or they may take the form of less easily observed differences in soil properties, plant species composition, or wildlife habitat quality. Research in protected area-centered ecosystems (PACEs) in the western USA was conducted to determine whether such ecotones can be detected and which factors might influence their emergence. This concept was tested in PACEs surrounding Grand Canyon (Arizona), Lassen Volcanic (California), Rocky Mountain (Colorado), and Sequoia and Kings Canyon (California) national parks. Plot-scale vegetation and soils data were collected along boundaries separating federal lands managed by the National Park Service, US Forest Service, and Bureau of Land Management, using a clustered sampling approach that held elevation, dominant vegetation type, soil parent material, and topography constant between contrasted plots. Additionally, interviews were conducted with managers of jurisdictions within the PACEs to determine how management actions might influence conditions across boundaries. Results/Conclusions Ability to detect anthropogenic ecotones varied with PACE and with the ecological property measured. For example, some vegetation and soil properties differed between jurisdictions at Grand Canyon after accounting for differing fire and livestock grazing histories. Conversely, subtle differences in non-native species presence were observed across boundaries at Sequoia-Kings Canyon but these were not statistically significant. Results suggest anthropogenic ecotones do exist in large undeveloped landscapes, but the timing of emergence and contrast along boundaries is influenced by the intensity of land uses and human activity, presence of fences, ecological property measured, and type and frequency of collaborative interactions between managers of adjoining jurisdictions.
