DOI: 10.5061/dryad.c2v92
title: Data from: Environmental heterogeneity has a weak effect on diversity during community assembly in tallgrass prairie

description: Understanding what constrains the persistence of species in communities is
 at the heart of community assembly theory and its application to
 conserving and enhancing biodiversity. The “environmental heterogeneity
 hypothesis” predicts greater species coexistence in habitats with greater
 resource variability. In the context of community assembly, environmental
 heterogeneity may influence the variety and strength of abiotic conditions
 and competitive interactions (environmental filters) to affect the
 relative abundance of species and biodiversity. We manipulated key
 resources that influence plant diversity in tallgrass prairie (i.e., soil
 depth and nitrogen availability) to increase environmental heterogeneity
 prior to sowing native prairie species into a former agricultural field.
 We compared variability in nutrient availability, aboveground annual net
 primary productivity (ANPP), and the composition of species between
 replicate plots containing soil heterogeneity manipulations and plots with
 no resource manipulations (n = 4 per treatment) during the first 15 yr of
 community assembly as a test of the “environmental heterogeneity
 hypothesis.” The manipulations increased environmental heterogeneity,
 measured as the coefficient of variation in NO3-N availability and ANPP.
 Plant diversity, however, was similar and decayed exponentially and
 indiscriminately over time between the heterogeneity treatments. Species
 richness declined linearly over time in both heterogeneity treatments, but
 richness was higher in the more heterogeneous soil 2 yr following a second
 propagule addition 8 yr after the initial sowing. As a result, there was a
 lower rate of species loss over time in the more heterogeneous soil (0.60
 species yr−1) relative to the control soil (0.96 species yr−1).
 Communities in each treatment exhibited strong convergence over time
 resulting from a shift in dominant species across all treatments and a
 gradual increase in the clonal C4 grass, Andropogon gerardii. We attribute
 the weak effect of heterogeneity on diversity to increasing dominance of a
 clonal species, which decreased the scale of soil treatments relative to
 plant size, dispersal limitation, and absence of a key driver (grazing)
 known to increase plant diversity under a frequent fire regime. Thus,
 steering community assembly to attain high biodiversity may depend more on
 manipulating processes that reduce dominance and facilitate the arrival of
 new species than promoting environmental heterogeneity.
description: Subplot and whole-plot
 dataData are provided in one
 file corresponding 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 and whole-plot data
 are in different tabs (pages) labeled within the Excel file. Data include
 annual aboveground net primary productivity, available nitrate in soil,
 species diversity, species richness, and percent cover of each plant
 species.Baer et al ANPP NO3 H R and
 SPCOV.xlsx