How to promote Sphagnum lawn establishment in drained bogs: the role of water table and moss vitality

Many Sphagnum-dominated peatlands (mainly bogs) in Europe and North America have been drained and degraded by agricultural use or peat extraction, negatively affecting the ecosystem services they provided in their natural state. The goals of bog restoration are: (1) the return of typical bog hydrology; and (2) a vegetation cover dominated by Sphagnum. Despite abundant research, spontaneous establishment of Sphagnum is often very slow or even fails. However, rapid establishment of Sphagnum is essential for both bog restoration and the profitable cultivation of Sphagnum in paludiculture. In the present study we focus on how we can enhance the development of Sphagnum lawns on drained peatlands by rewetting them and actively adding living Sphagnum fragments (founder material). Our glasshouse, mesocosm and field experiments in Germany and Georgia show that the founder material should ideally provide a high initial cover of vital Sphagnum (mainly capitula) on a levelled peat surface that is close to the (permanently high) water table. In drier conditions, Sphagnum plants can be introduced as plugs or the founder material can be covered with straw mulch to accelerate establishment. Using these methods it is possible to establish Sphagnum lawns within 1–2 years, even under nutrient-rich conditions on a former bog grassland in NW Germany.