Fen restoration: defining a reference ecosystem using paleoecological stratigraphy and present-day inventories

Choosing past and present-day indicators could strengthen the reference ecosystem used for ecological restoration projects. Based on the paleoecological analysis of four peat cores and the characterization of 13 contemporary natural sites, the reference ecosystem for minerotrophic peatlands in southeastern Canada is composed of two broad categories of plant assemblages described as tall-sedge and Sphagnum–Thuja/brown moss. In paleoecological peat profiles, tall-sedge communities were found at the transition between aquatic and terrestrial, and were associated with high graminoid production, riverine peatlands, and elevated water table in the present-day analyses. Sphagnum–Thuja communities resemble the present-day vegetation found in natural basin type peatlands. Except for Sphagnum warnstorfii Russ., these communities, with high taxonomical diversity, contain more generalist species from boreal peatland vegetation, such as Rhododendron groenlandicum (Oeder) Kron & Judd, Thuja occidentalis L., Linnaea borealis L., and Maianthemum trifolium L. They grow in dryer or shady habitats such as hummocks or forest understory. The importance of brown mosses was revealed by paleoecological analysis. Overall, findings from both approaches are complementary: paleoecological stratigraphy informs us about past ecosystem dynamics, while present-day inventories allow us to define current plant communities and their major environmental characteristics. The range of variability of vegetation and environmental variables found in these studies are essential tools for fen restoration projects.