Differences in Shallow Groundwater Dynamics Between Disturbed and Undisturbed Peatlands on Brier Island, Nova Scotia: Implications for Persistence of Geum peckii in Big Meadow Bog

The goal of our project was to provide data that would help identify what hydrologic conditions were typical of relatively undisturbed and disturbed peatlands on Brier Island and what aspects of those conditions were most conducive to supporting healthy populations of Geum peckii. We instrumented 8 sites with shallow wells and automated data loggers spread widely across Brier Island in 2014 and 2015 to monitor shallow groundwater dynamics. Seven of the sites were reference peatlands—two horizontal fens, three basin bogs, one domed bog-fen complex. The other site was the Big Meadow Bog complex within which we incorporated data from 4 wells. One of the most important findings from our study was that there were clear differences in shallow water level dynamics among our four peatland classes. Mean water levels, monthly fluctuations and water table depth durations ranged along a spectrum from highly consistent among the three undisturbed fens to highly variable among the three disturbed bogs. Peatlands with intermediate hydrological patterns between the greater constancy and wetness of the undisturbed fens and the hypervariability and dryness of the disturbed bogs are largely those that supported substantial populations of Geum peckii. Identifying the hydrologic sweet spot for Geum peckii success was not the primary objective of this study, but our results suggest that mean water levels of −10 to −20 cm and overall water levels in the saturated root zone for about 75% of the time are two key aspects of the hydrologic niche space that generally lead to success for this species. However, it is important to note that the results of other studies included in this volume strongly suggest that while suitable hydrology is critical to the success of Geum peckii, other habitat factors (e.g., shrub density, microtopography) also play key roles.