Long-term responses of birds to the creation of a community fuel break in the western boreal forest of Canada: implications for management within protected areas

摘要

Encroachment, including human settlement, into the North American boreal forest has increased substantially in recent decades. This has resulted in changes in the dynamics, distribution, and functioning of this system with potential negative implications for avifaunal communities. Fuel breaks are often constructed around human settlements in forested landscapes to reduce the potential of damage to infrastructure from wildfires. The frequency and intensity of wildfire in boreal landscapes is projected to increase under future climate change scenarios. Thus, fuel breaks may become a more common management system around communities in the boreal forest. We assessed the responses of 21 bird species to the creation of a fuel break constructed around the village of Waskesiu in Prince Albert National Park, Saskatchewan, Canada. We surveyed birds for 2 years before (2000, 2001) and in 11 of 16 years after clearing (2002-2017; n = 14 sites) relative to reference sites (n = 3 sites surveyed since 2000 and n = 14 sites surveyed since 2006). The fuel break (~247 ha) was created in mature aspen-spruce forests and resulted in habitats resembling open parkland and open deciduous forest through removal of ~95% of the coniferous trees and continuous firebreak management. A community-level analysis indicated that open- and shrub-dwelling bird species became dominant following fuel break creation and for the duration of the study. Individual species-level analyses indicated declines in four avian species associated with older boreal forests (e.g., Bay-breasted Warbler, Setophaga castanea) and increases of six avian species typical of open and shrub habitats (e.g., White-throated Sparrow, Zonotrichia albicollis). However, trends of most species were similar in reference and fuel break sites likely due to the close proximity of reference sites to the fuel break. The fuel break in our study negatively affected most avian species that require older forests and, with ongoing maintenance, fuel breaks represent an unnatural component of the landscape in protected areas. Planned and ongoing expansion of the Waskesiu fuel break and creation of another fuel break (additional ~395 ha) in Prince Albert National Park including clearing to protect commercial property outside the park warrant additional investigations into the impacts of fuel breaks on birds and other wildlife.