Linear Disturbances in the Livingstone-Porcupine Hills of Alberta: Review of Potential Ecological Responses
Dan Farr, Andrew Braid, and Simon Slater
A considerable body of information is available in the scientific literature to evaluate potential ecological responses to linear disturbances in the eastern slopes of the Rocky Mountains. Drawing from a previous assessment of biological and ecological responses to a range of human activities in the Castle area of southwestern Alberta, this report provides a supplementary analysis specific to the Livingstone-Porcupine Hills, located just north of the Castle area. This report focuses on information related to linear disturbances to inform ongoing dialogue on managing land use and human activities. We provide an overview of relevant evidence from the Castle regional assessment, summarize relevant published case studies, and document the current extent of linear disturbances in the Livingstone-Porcupine Hills region.
Government records supplemented by non-government sources indicate that there are over 4,000 kilometers of roads and trails in the Livingstone-Porcupine Hills region. While comprehensive data on the use of these linear features by people are not available, the region is a popular destination for recreational use of off-highway vehicles, and anecdotal observations indicate high levels of motorized use in certain parts of the region.
Estimates of linear disturbance density, which range from 0.9 to 5.9 km/km2 among the 20 watersheds in the region, exceed those recently calculated for the Castle Parks area to the south, in which densities ranged from 0.5 to 3.4 km/km2. An extensive network of intermittent and continuously-flowing streams in the region is estimated to cross these linear disturbances more than 3,000 times, with potential consequences for stream-dwelling species.
Based on an existing body of published research, linear disturbances have the potential to cause a range of ecological responses including stream sedimentation, vegetation disturbance, spread and establishment of invasive species, and a range of behavioural and population-level responses of grizzly bears and other wildlife. Additional focused monitoring and research is needed to further understand the extent and magnitude of these and other potential responses in the Livingstone-Porcupine Hills region. Because variability in the volume, timing and type of off-highway vehicle affects the manner in which terrestrial and aquatic ecosystem attributes may respond, an adaptive monitoring program to characterize vehicle use and related responses of relevant biological and ecological parameters would inform future assessments of the efficacy of actions to achieve management objectives in the area.