PEATLANDS Recolonisation by Spontaneous Vegetation of a Rewetted Peatland after Topsoil Removal: a Focus on Biomass Production and Nutrient Uptake Vittoria Giannini 1 & Andrea Bertacchi 2 & Enrico Bonari 1 & Nicola Silvestri 1,2 Received: 6 November 2018 /Accepted: 13 March 2019 # Society of Wetland Scientists 2019 Abstract The ability of spontaneous vegetation to recolonise a Mediterranean peatland was investigated to assess the combined effect of rewetting and topsoil removal on restoration of a drained area. The experiment tested the concept of converting the cultivated area into a constructed wetland system (CWS) of five cells. A mixed approach was used based on orthophotos from an unmanned aerial vehicle, phytosociological surveys, and destructive samplings performed during the fourth summer after the CWS set-up. Two spontaneous species dominated: Phragmites australis (Cav.) Trin. ex Steud. and Typha latifolia L.. Distance of the CWS from the inlet influenced the biomass yield of P. australis, which progressively decreased (from 7.81 to 3.87 kg/m 2 ) and thus influenced other parameters, such as nitrogen (N) and phosphorus (P) uptake per unit area (from 153 to 74 g N/m 2 , from 13 to 7 g P/m 2 ). Typha latifolia, with a mean production of 3.58 kg/m 2 (in the last two (4th and 5th) CWS cells), took up 51 g N/m 2 and 6 g P/m 2 . From these data, we determined that plants took up 1144 kg of N and 103 kg of P in their aboveground biomass and were able to store nearly 25% of the nutrient loads yearly. Keywords Phytotreatment . Phragmites . Typha . Drainage water . Nitrogen . Phosphorus Introduction After nearly a century of intensively draining peatlands for agriculture around the world, several environmental problems have arisen. The most important ones are subsidence (gradual lowering of the soil level due to compaction after draining), increased rate of soil organic matter (SOM) mineralisation, and internal eutrophication due to the transfer of nutrients from SOM mineralisation into receiving water bodies (Joosten and Clarke 2002; Tiemeyer et al. 2007). Restoring peatlands is necessary to reclaim the multiple ecosystem ser- vices these areas provided before their exploitation. With this perspective, the first step is rewetting the peatland, followed by the essential step of reducing the trophic status of the degraded peatland to avoid transferring nutrients into drainage water, which promotes eutrophication (Zak et al. 2010; Zak et al. 2017). This latter step consists of removing the mineralised topsoil layer (Van Diggelen et al. 1996; Smolders et al. 2008; Emsen et al. 2015). These combined strategies leave the soil bare, providing a unique opportunity to study the recolonisation success of spontaneous vegetation. The basic hypothesis of the present study is that construct- ing wetlands as a rewetting strategy for degraded peatland after topsoil removal promotes a more multi-structured resto- ration process that meets several goals: i) recolonising the area with the most suitable plant species, ii) reducing the trophic status of the area by removing topsoil and forcing eutrophicated drainage water used for rewetting through a constructed wetland system (CWS) to remove nutrients (Comin et al. 1997; Shutes et al. 1999; Huett et al. 2005), and iii) using the vegetation that recolonises the area as a filter * Vittoria Giannini v.giannini@santannapisa.it Andrea Bertacchi andrea.bertacchi@unipi.it Enrico Bonari e.bonari@santannapisa.it Nicola Silvestri nicola.silvestri@unipi.it 1 Institute of Life Sciences, Scuola Superiore Sant’Anna , Pisa, Italy 2 Department of Agriculture, Food and Environment (DAFE), University of Pisa, via del Borghetto, 80, Pisa 56124, Italy Wetlands https://doi.org/10.1007/s13157-019-01141-2