DOI: 10.25829/bexis.31496-8
title: Data and code for the manuscript Freitag et al. 'Increasing plant species richness by seeding has marginal effects on ecosystem functioning in agricultural grasslands'

description: This is the data and code to reproduce the analysis of the manuscript Freitag et al. 'Increasing plant species richness by seeding has marginal effects on ecosystem functioning in agricultural grasslands'. The data comes as a .zip folder of a RStudio project with data (in the data/ folder), R scripts (in the R/ folder).
description: Study Design: We analysed 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.<br> 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. <br> We surveyed vegetation and measured productivity annually in May from 2015 to 2019 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. In May 2018 and 2019, we measured several ecosystem functions on each of the 7 m × 7 m subplots in the grasslands.<br>See Freitag et al. ' Increasing plant species richness by seeding has marginal effects on ecosystem functioning in agricultural grasslands' for details. |Data preparation: The .zip folder contains a data/ folder with all datasets that were used in the manuscript:<br>1. 'metadata.txt'<br>The metadata.txt file provides metadata and ecosystem function data sampled in the experiment. We used a two-factorial seeding and topsoil disturbance experimental design.<br>Grassland-level land-use intensity ('LUI') data was averaged for the years 2014-2018 and includes fertilization (in kg Nitrogen ha-1), grazing (in livestock unit grazing days × ha-1) and mowing (average mowing frequency per year) intensities. Data was downloaded using the LUI calculation (Ostrowski et al. 2020) implemented in BExIS (re3data.org: Biodiversity Exploratories Information System).<br>See a detailed description of the variables in the attachment.<br>2. 'species-wide.txt'<br>Species cover data from vegetation records. Each row corresponds to an observation of a 7 m × 7 m treatments ('treatment') sampled in the 73 grasslands in a given year ('plotIdent'). Data is from BExIS dataset ID 26746.<br>3. 'traits.txt'<br>We used species-specific means of specific leaf area ('SLA', aggregated from TRY, Kattge et al., 2019) and fine root diameter ('root.diameter', Lachaise et al., 2021). BExIS dataset IDs 27610 and 26587. |Data analysis: The R/ folder contains all R scripts.<br>'00_data-wrangling.R': this is the starting point of the analyses. It calculates plant community metrics and prepares ecosystem function data for analysis.<br>The prepared data is written to 'functions-dataset.txt' in the data/ folder.<br>The following '01-1_treatment-effects.R', '01-1_within-effects-richness.R' and '01-2-among-effects-richness.R' represent the three analyses.<br>'02-1_plots-within-effects-richness.R' and '02-1_plots-within-effects-richness.R' and '02-2_plots-among-effects-richness.R' can be used to replicate the figures shown in the manuscript.<br>'helpers.R' is a short script with helper functions. |Literature references: Kattge, J., Bönisch, G., Dıaz, S., Lavorel, S., Prentice. I.C., Leadley, P. et al. (2020) TRY plant trait database–enhanced coverage and open access. Global Change Biology 26, 119–188.<br>Lachaise, T., Bergmann, J., Rillig, M.C. Kleunen, M. van. (2021) Below- and aboveground traits explain local abundance, and regional, continental and global occurrence frequencies of grassland plants. Oikos, 130, 110–120.brOstrowski, A., Lorenzen, K., Petzold, E. Schindler, S. (2020) Land use intensity index (LUI) calculation tool of the Biodiversity Exploratories project for grassland survey data from three different regions in Germany since 2006, BEXIS 2 module. Zenodo, https://doi.org/10.5281/zenodo.3865579.