Spatially explicit climate change projections for the recovery planning of threatened species: The Bicknell's Thrush (Catharus Bicknelli) as a case study

Abstract

With climate change, natural resource managers are faced with the challenging task of planning the conservation of habitat for threatened species. Classified as ''threatened'' under the Species at Risk Act in Canada, the Bicknell's Thrush (Catharus Bicknelli - BITH) is a migratory bird whose range is highly restricted. Bioclimatic models project more than 50% loss of suitable habitat - high elevation dense balsam fir (Abies balsamea) forests - in the northeastern USA by 2050 due to climate change. We used BITH as a case study to demonstrate the value of forest landscape models (e.g., LANDIS-II) to support decision-making on conservation of habitat of threatened species. We modeled the impacts of forest management and natural disturbances, as well as climate-induced changes, on forest stand and landscape structure. Under RCP climate forcing scenarios 2.6, 4.5 and 8.5, simulations projected significant changes in dominant tree species biomass, from coniferous to broadleaved deciduous, implying important losses of mature balsam fir forest. Climate change was projected to have severe effects with major changes projected to occur after 2080 and losses of more than half of BITH suitable habitat by 2100 for “worst-case” climate change scenarios. This contrasts with results from bioclimatic models which do not capture the expected lags in vegetation responses to changing climate. Our results also suggest that innovative forest management strategies could help maintain BITH habitat abundance under RCP 2.6 and RCP 4.5 climate forcing. Such results can provide guidance for considering effective long-term conservation of habitat for threatened species in a changing world. Keywords: Forest landscape models, Mountain forest habitat, Forest management, Boreal forest, Critical habitat, Balsam fir (Abies balsamea), Elevation