Rewetting in Mediterranean reclaimed peaty soils and its potential for phyto-treatment use

摘要

AbstractA pilot experimental field combining rewetting of reclaimed peaty soils and water phyto-treatment was set up in the Massaciuccoli Lake basin (Tuscany, Italy) to reduce the water eutrophication and peat degradation caused by almost a century of drainage-based agricultural use.In this paper, we investigated the restoration process occurring consequently to the conversion of a drained area in a natural wetland system (NWS) (the partial top soil removal, the realization of a perimeter levee to contain the waters, the rewetting with the drainage waters coming from the of surrounding cultivated areas) and the capability of the spontaneous vegetation to catch nutrients acting as a vegetation filter.To follow the restoration process over time (2012–2016), we used a mixed approach merging phytosociological surveys with ortophotos taken by an Unmanned Aerial Vehicle (UAV). During the last year of observation (2016), we performed destructive sampling on the most widespread plant communities in the area (Phragmites australisandMyriophyllum aquaticumcommunity) to quantify the biomass production and the uptake of nitrogen and phosphorus.Stands ofPhragmites australis (Cav.) Trin. ex Steud. yielded more thanMyriophyllum aquaticum(Vell.) Verdc. (4.94 kg m-2 vs 1.08 kg m-2).M. aquaticumshowed higher nutrient contents (2.04% of N and 0.35% of P), howeverP. australiswas able to take up more nutrients within the NWS because of its larger cover and productivity.In the perspective of maximizing the plant development and consequently the amount of nutrients extracted from treated waters, the authors suggest 4-5 year-long-harvesting turns, better occurring in spring-summer.Highlights•Rewetting peaty soils, former drained for agricultural purposes, can contribute to increase the diversity of species.•The combined use of UAVs and field surveys provides a snapshot of the surface covered by the different species every year.•P. australisandM. aquaticumcan take up remarkable quantities of nitrogen and phosphorus from eutrophicated environment.