Ericaceae stabilize peat and foster Sphagnum majus establishment at pool margins in restored peatlands

• Innovative restoration approach specific to peatlands pools.
• Ericaceous shrubs transplanted near pools reduce frost heave by 52%.
• Ericaceae promote Sphagnum majus establishment at water edge of restored pools.

Pools are recognized as biodiversity hotspots in natural peatlands, thus creating pools would increase the ecological value of restored peatlands. However, the peaty margins of artificial pools are unstable, as frost heave creates much surface erosion restricting establishment of vascular plant seedlings. This study evaluates the ability of heather shrubs (Ericaceae) to stabilize created pool margins in restored peatlands. Andromeda polifolia var. latifolia and Vaccinium macrocarpon plants were introduced to form a sparse cover (<25%) at pool margins. Sphagnum majus fragments were spread simultaneously between the shrubs over half the surface at a density of 50% in ground cover, and seeds of herbaceous plants typical of pool margins were sown at two distances from the low-water mark (0.5 and 3.5 m). We examined the impact of Ericaceae on (1) frost heave intensity, (2) S. majus establishment and (3) herbaceous species establishment. Treatments using ericaceous shrubs or Sphagnum, both alone or in combination, all reduced frost heave by about 50%. After one year, it also increased survival of S. majus (four-fold) on the wettest soil along the banks. However, at a greater distance from the water (2 and 3.5 m), the Sphagnum cover was not influenced by the presence of Ericaceae. Establishment and growth of herbaceous plants grown from seeds were not influenced by the presence of Ericaceae. This study demonstrates the potential of Ericaceae for stabilizing the peat substrate close to the water line and improving survival of S. majus introduced at the immediate edge of created pools.