Restoring plant diversity in lowland grasslands: efficacy of different seed addition and soil preparation methods (dataset)

The biodiversity of semi-natural grasslands has dramatically declined over the past century. We experimentally tested, at field scale, the efficacy of different assisted (active) restoration methods to enhance plant biodiversity in species-poor, extensively managed lowland meadows. Four restoration treatments, plus one control were randomly allocated to five meadows at 12 spatially-replicated study sites in the Swiss lowlands in 2019: 1) hay transfer from a species-rich donor meadow on a harrowed meadow; 2) the same as 1 but on a ploughed meadow; 3) sowing a directly harvested native seed mixture originating from a species-rich donor meadow on a ploughed meadow; 4) sowing a multiplied native seed mixture on a ploughed meadow; 5) control, i.e. with no soil disturbance and no reseeding. Vegetation surveys were performed before (2018) and after the restoration actions (2021 and 2023). After a pronounced biodiversity rise in 2021, plant species richness had stabilized by 2023 across most treatments with, on average, 29% more species compared to 2018 and 16% more species in restored compared to control meadows in 2023. Moreover, 90% of the restored meadows qualified for the result-based payment scheme in 2023. Harrowing before seeding was as effective as ploughing. While the multiplied seed mixture initially showed a stronger increase, this effect had decreased by 2023, reaching levels comparable to the other treatments. Beta diversity was higher in hay transfer treatments than in the control and other restoration treatments, indicating greater heterogeneity in community composition. Findings provide evidence-based guidance for cost-effective and practically feasible grassland restoration.

The dataset represents a list of the study meadows with their respective vegetation data. The identification name for each meadow is composed by two capital letters that indicate the study site and by the abbreviation of the treatment (c = Control, hth = Hay Transfer on a Harrowed meadow, htp = Hay Transfer on a Ploughed meadow, dsp = Directly harvested native Seeds on a Ploughed meadow, msp = Multiplied native Seeds on a Ploughed meadow). The coordinates are expressed in the Swiss coordinate system LV95, where the first number indicates the position on the axis East-West, and the second one on the axis South-North. The coordinates given for the first plot represent the location of the first random point and the ones given for the second plot represent the second point, placed at 14 m of distance from the first one. For each plot we recorded the cover for each plant species. The cover is expressed in percentages.