Standing tall together: Peatland vascular plants facilitate Sphagnum moss microtopography

Abstract

To preserve the heterogenic and diverse nature of peatland ecosystems, a well-functioning plant community is imperative. In intact peat bogs, such communities consist of a balanced mix of peat mosses and vascular plants across a hydrological gradient. Vascular plants compete with peat mosses – the ecosystem builders in ombrotrophic peatlands – for resources such as nutrients and light, but also provide structure for peat mosses to grow. In contrast, peat mosses create an adverse environment in which only certain plant species can find a niche. In light of the competition–facilitation gradient between peatland plants, the role of vascular plants as facilitators for peatland microhabitat formation is mainly overlooked.

Using a long-term vascular plant removal experiment in Store Mosse National Park, Sweden, this study assesses the role of the functional type composition of the vascular plant community as a mechanical structure to support the peat moss (Sphagnum) carpet.

Our data highlights the importance of vascular plant functional type diversity in facilitating the structure of the Sphagnum carpet. Ericoids are crucial for the maintenance of hummocks. Moreover, recolonization of ericoids after removal of vascular plants enabled the recovery of the Sphagnum carpet in this microtopography. Graminoids provide at most ’co-facilitation’ of the structural support to the Sphagnum carpet. These results show that the composition of the vascular plant community determines how strongly they can contribute to structural support and indicate that restoration of the vascular plant community can be used as a tool to restore peat moss microtopographies, leading to a heterogenic and diverse peatland plant community.