DOI: 10.5061/dryad.5x69p8d32
title: Soil resources mediate the strength of species but not trait convergence across grassland restorations

description: Ecological restoration is notoriously unpredictable because similar
 actions can result in different outcomes. Outcomes can also differ for
 species and functional components of communities depending on how
 restoration actions and abiotic conditions alter community assembly
 trajectories. Quantifying variation in community trajectories across
 restorations for both species and traits is rare, but can help to resolve
 underlying assembly processes and refine strategies to maximize
 restoration success. We quantified the importance of soil resources, seed
 mix richness, and prescribed fire for variation in plant species and
 functional trait trajectories over six years across 20 restored tallgrass
 prairies in the midwestern United States. We predicted stronger
 convergence for traits than species, with species and trait compositions
 converging more across restorations on resource-poor soils and with
 frequent fires due to stronger abiotic filtering. In contrast, we
 predicted species and trait compositions would converge more slowly or
 diverge across restorations with resource-rich soils, with less frequent
 fires, and seeded with more species due to weaker filtering and more
 stochasticity. Communities generally converged over time; however, the
 rate of convergence was determined by soil resources, not restoration
 actions. Restorations converged more across resource-rich sites. In
 contrast to patterns of species convergence, variation in trait
 composition remained stable over time regardless of soil resources or
 restoration actions. The unexpected pattern of species, but not trait,
 convergence during community assembly appears to result from increasing
 dominance of a native C4 bunchgrass, Andropogon gerardii, that coincides
 with proportional declines of other C4 grasses that share similar traits.
 Synthesis and applications: restoration outcomes may be more predictable
 than typically considered. Trait compositions were stable and variation in
 species compositions decreased over time owing to site conditions, where
 resource-rich soils produced more consistent outcomes. Our study shows
 monitoring multiple facets of biodiversity across restorations can reveal
 why outcomes vary and inform broad-scale restoration planning. 
description: The datasets were collected in 20 restored tallgrass prairies in
 southwestern Michigan, USA. The raw data and code provided were used to
 derive the analysis dataset (also included) to produce all results and
 figures reported in the main paper referenced above. 
 species_plot_data.csv: This data file includes herbaceous plant
 community composition data sampled in 2011, 2013, and 2016 for each of
 20 restored tallgrass prairies in Southwestern Michigan. Values denote the
 percent cover of each plant in 10 1-m<sup>2</sup> plots spaced
 evennely along 45-m transects randomly oriented in the center of each
 site. Species percent cover in a given plot can sum to more than 1 if
 individuals are overlapping, or sum to less than 1 when bareground is
 present.  site_predictors.csv: This data file includes
 all the site identifiers and predictor variables (soil types, prescribed
 fire frequency, seed mix richness) used in the analyses. 
 DATA_model_metrics: This data file includes the final species and
 trait dissimilarities, along with all relevant predictor variables, used
 to model changes in variation in community composition across
 restorations. Species and trait dissimilarity values are the distance from
 the centroids of all sites in principal coordinate space. These values are
 calculated from the raw composition data using the accompanying R
 scripts. 
description: See README_catano_datasets.txt for metadata and usage
 notes The readme
 file contains descriptions for each dataset and variables. It also
 details script used to produced the derived data used in analyses. Full
 details of analyses and methods are described in the associated manuscript
 referenced above.