SPHAGNUM REGENERATION ON BARE PEAT SURFACES - FIELD AND GREENHOUSE EXPERIMENTS

The re-establishment of Sphagnum mosses on bare peat surfaces is one o f the main challenges faced in the restoration of post-harvested peatl ands. One suggested approach to ensure moss recolonization is to use f ragments of Sphagnum plants collected from a natural area as diaspores . The regeneration and recolonization potential of fragments of differ ent species of Sphagnum were tested on bare peat, both in the field an d in a greenhouse. We examined how diaspore size, density and depth of origin influence recolonization and re-establishment success. The gre enhouse experiment also tested the impact of water level on Sphagnum r egeneration and recolonization. 2. Field and laboratory experiments sh owed that only the surface layer (0 10 cm) of a peat profile contained enough viable material to be of practical use as a source of diaspore s. 3. Small (0.5-cm), medium (1-cm) or large (2-cm) diaspores had simi lar recolonization success. Obtaining a precise and even size of fragm ents will not, therefore, be an important aspect to consider when scal ing up to the quantities needed for restoring large surfaces. 4. Green house experiments showed that water level in the peat column greatly i nfluences the recolonization success of Sphagnum diaspores. Most speci es reacted positively to wetter conditions, with the notable exception of S. fuscum. 5. A density of 450 Sphagnum plants per m(2) resulted i n some Sphagnum species covering up to 50% of the peat surface in 3 mo nths and 100% in 6 months, when the water table was close to the peat surface in the greenhouse experiment. Sphagnum cover reached 5-10% aft er 3 months in the drier treatments of the greenhouse experiment and w as generally comparable to the results obtained in the field after one season of growth under shade cloth. 6. Improving the humidity conditi ons offered to diaspores is by far the most promising approach to redu ce the quantity of diaspores needed to re-establish a significant moss cover rapidly on a post-harvested surface. The selection of appropria te species and densities according to the dryness of the surface to be restored are two other elements to consider in minimizing the amount of source material needed for restoration.