DOI: 10.5061/dryad.63n980b
title: Data from: Soil heterogeneity increases plant diversity after twenty years of manipulation during grassland restoration

description: The ‘environmental heterogeneity hypothesis’ predicts that variability in
 resources promotes species coexistence, but few experiments support this
 hypothesis in plant communities. A previous 15-y test of this hypothesis
 in a prairie restoration experiment demonstrated a weak effect of
 manipulated soil resource heterogeneity on plant diversity. This response
 was attributed to a transient increase in richness following a
 post-restoration supplemental propagule addition, occasionally higher
 diversity under nutrient enrichment, and reduced cover of a dominant
 species in a subset of soil treatments. Here, we report community dynamics
 under continuous propagule addition in the same experiment, corresponding
 to 16-20 y of restoration, in response to altered availability and
 heterogeneity of soil resources. We also quantified traits of newly added
 species to determine if heterogeneity increases the amount and variety of
 niches available for new species to exploit. The heterogeneous treatment
 contained a factorial combination of altered nutrient availability and
 soil depth; control plots had no manipulations. Total diversity and
 richness were higher in the heterogeneous treatment during this 5 y study
 due to higher cover, diversity, and richness of previously established
 forbs, particularly in the N-enriched subplots. All new species added to
 the experiment exhibited unique trait spaces, but there was no evidence
 that heterogeneous plots contained a greater variety of new species
 representing a wider range of trait spaces relative to the control
 treatment. The richness and cover of new species was higher in N-enriched
 soil, but the magnitude of this response was small. Communities assembling
 under long-term N addition were dominated by different species among
 subplots receiving added N, leading to greater dispersion of communities
 among the heterogeneous relative to control plots. Contrary to the
 deterministic mechanism by which heterogeneity was expected to increase
 diversity (greater variability in resources for new species to exploit),
 higher diversity in the heterogeneous plots resulted from destabilization
 of formerly grass-dominated communities in N-enriched subplots. While we
 do not advocate increasing available soil N at large scales, we conclude
 that the positive effect of environmental heterogeneity on diversity can
 take decades to materialize and depend on development of stochastic
 processes in communities with strong establishment limitation.
description: Baer et al 2019
 Ecological Applications Data FileData correspond to
 subplot and whole-plot analyses of the “Prairie Restoration Heterogeneity
 Plots” located at the Konza Prairie Long Term Ecological Research site in
 Manhattan, KS USA. Subplot light and nitrogen availability from 2013-2017,
 subplot plant diversity and species composition from 2013-2017, plot
 diversity and species composition from 1998-2017, and plant trait data are
 located in four different tabs (pages) within the Excel
 file.Baer
 et al 2019 Ecological Applications Data NO3 PAR H R
 SPCOV.xlsx