Hydrologic assessment of mineral substrate suitability for true moss initiation in a boreal peatland undergoing restoration

Tens of thousands of oil and gas well pads have been constructed in peatlands on the North American Western Boreal Plain. The introduction of true mosses directly onto residual mineral substrates left following the partial removal of well pads may present a means of re-establishing peatland ecosystem function on these sites post-decommissioning. Accordingly, an assessment of mineral substrate moisture dynamics was undertaken on a residual well pad on the Western Boreal Plain to determine whether requisite conditions for the establishment of true mosses would be maintained throughout the growing season. The results indicate that substrate moisture conditions were most favourable for true moss establishment when the water table was maintained within 6 cm of the mineral surface of the residual well pad. Such conditions were most frequently observed along edges of the pad receiving direct groundwater inputs from an adjacent peatland, representing an area covering just under half of the pad. However, water table variation was high in interior areas of the pad which were hydrologically disconnected from the adjacent peatland. Here, substrate moisture dynamics were not optimized for true moss establishment late in the season. Mosses introduced to these areas faced a considerable risk of desiccation, which was not directly alleviated by the application of a straw mulch. These findings suggest that the partial removal technique has the potential to create requisite moisture conditions for true moss establishment, but there is a need to enhance subsurface hydrological connectivity across residual pads in future implementations.