A testate amoeba-based transfer function for paleohydrological reconstruction from boreal and subarctic peatlands in northeastern Canada

Testate amoebae are common proxy for water table depth in peatlands and are commonly used to reconstruct past hydroclimatic conditions. In northeastern America, previous transfer function development was mostly limited to ombrotrophic peatlands from continental and/or oceanic contexts. This study provides a greater range of modern analogues (n = 206) from ombrotrophic to poor minerotrophic peatlands along an ecoclimatic gradient from boreal to subarctic in both continental and oceanic regions. Multivariate analysis confirmed that water table depth is the dominant control on species distribution, and a new transfer function was developed for this environmental parameter. The WA.inv model has a RMSEP of 5.44 cm and R2 of 0.80. The effect of spatial autocorrelation on the predictive power and statistical significance of this transfer function was also tested using newly developed statistical tests. We also improved modern analogues for two problematic species (Hyalophenia subflava and Difflugia pulex). This new testate amoeba transfer function will improve paleohydrological reconstructions from high-latitude peatlands (e.g. subarctic fens) and increase our ability to evaluate their sensitivity to ongoing climate change.