DOI: 10.25829/bexis.30915-10
title: Data and Code for the manuscript Freitag et al. 'Restoration of plant diversity in permanent grassland by seeding: assessing the limiting factors along land-use gradients'

description: This is the data and code to reproduce the analysis of the manuscript Freitag et al. 'Restoration of plant diversity in permanent grassland by seeding: assessing the limiting factors along land-use gradients'. The data comes as a .zip folder of a RStudio project with data (in the data/ folder), R scripts and rmardown files (in the doc/ folder) to reproduce the analyses and manuscript. Code without data can also be found at https://github.com/martin-freitag/restoration-by-seeding/tree/v1.0.0.
description: Study Design: We analysed five years of a seeding and topsoil disturbance experiment in 73 grasslands. We installed the experiment in three German regions that span gradients in soil characteristics, elevation and climate that are representative of large parts of Central Europe. Within each region, we selected 23-25 permanent grasslands along gradients of land-use intensity, productivity and corresponding plant diversity, ranging from unfertilized sheep pastures with 70 species per 16 m2 to highly fertilized, productive and frequently mown grasslands with 10 species per 16 m2.|Sampling design: We established a 2 × 2 factorial experiment with seeding and topsoil disturbance in 73 grasslands. This resulted in four 7 m × 7 m treatments (control, seeding only, seeding and disturbance, disturbance only), which we arranged in a rectangle with 2 m distance between treatments (see appendix S1). In October 2014, we applied the disturbance treatment by mechanical perturbation of the established sward and the topsoil down to 10 cm with a rotary harrow or a rotary cultivator. For the seeding treatments, we used commercially available regional seed mixtures. The mixtures were selected from the regional species pools and included grasses, legumes and forbs.  We surveyed vegetation and measured productivity from 2015 to 2019 annually in May before the first mowing or grazing took place. On all four 7 m × 7 m treatments in each of the 73 grasslands, we recorded all vascular plant species on 2 m × 2 m quadrats and estimated percentage cover. Annually we clipped all living plant biomass on one square meter on the control treatments. We dried the biomass for 48 h at 80 °C and weighed it to the nearest gram. 
See Freitag et al. (2021) for details.|Data preparation: The .zip folder contains a data/ folder with five datasets that were used in the manuscript: 1. 'metadata.txt' The metadata.txt file provides metadata to the vegetation records sampled in the experiment over the five years. Columns correspond to unique observations ('plotIdent') sampled in the 73 grasslands ('plot') in three regions ('region') over five years ('year', 'SADEyear') and two-factorial diverse-seeding and topsoil disturbance treatments ('treatment', dummy-coded treatment variables 'seed' and 'dist'). Observation-level percentage covers of vegetation (cover.herbs.pc), litter (cover.litter.pc) and bare soil (cover.bare.soil.pc) and harvested biomass (biomass.g, in g biomass m-2) is provided as well. These variables were extracted from the BExIS datset IDs 19812, 20646, 23506, 24066 and 26747. Grassland-level land-use intensity data was averaged for the years 2014-2018 and includes fertilization ('Fert', in kg Nitrogen ha-1), grazing ('Graz', in livestock unit grazing days × ha-1) and mowing ('Mow', average mowing frequency per year) intensities (Vogt et al. 2019). Data was downloaded using the LUI calculation (Ostrowski et al. 2020) implemented in BExIS (re3data.org: Biodiversity Exploratories Information System). 
2. 'species-long.txt' Species cover data from vegetation records is available in long format in the file species-long.txt. Each row corresponds to a 'species' and its 'cover' of an observation ('plotIdent'). Data is from BExIS dataset ID 26746. 
3. 'LEDA-traits.txt' We used plant functional trait data saved in LEDA-traits.txt from the LEDA traitbase (Kleyer et al. 2008). We averaged canopy height ('height', in m), seed mass ('seedMass', in mg) and specific leaf area ('SLA', in mm2 mg^-1) measurements per species. 4. 'sown-species.txt' The sown-species.txt file lists the species in the seed mixtures of the three regions. Can be found in BExIS dataset ID 25987. 5. 'seeding-density-germination-rates.txt' The seeding-density-germination-rates.txt file contains the seeding densities of the species in the seed mixtures. Based on seed mass, we have sown seeds in three densities ('seeddensity', categorical, and 'seeddensity.per.m2', numeric). We estimated seed viability by counting the number of emerging seedlings in a germination test (germinationrate, percentage of germinated seeds). Germination data is from BExIS dataset ID 23706.