DOI: 10.5061/dryad.8gtht76w9
title: Data from: Native-exotic richness relationship in Michigan prairies

description: A better understanding of factors underlying positive correlations between
 native and exotic species richness, a pattern that is nearly ubiquitous at
 large scales in plant communities, may help managers modify these
 correlations to favor native plant species during restoration. Across 29
 tallgrass prairie sites restored through seed sowing onto former
 agricultural lands, we examined whether the relationship between native
 and exotic richness is: 1) altered by management, such as seed additions
 and prescribed fire, 2) controlled instead by environmental conditions and
 successional processes, or 3) altered by management in certain
 environments and not in others. Two datasets. Both contain exotic and
 native plant SR across several prairie restorations, as well as data on
 seed mix properties (mix richness, seeding rate), fire frequency, age of
 restoration. "BassettNativeExoticData" contains data on
 additional factors that influence invasion: environmental factors (PCA of
 surrounding land use, tillage history, plant biomass, CV of plant biomass,
 total vegetative cover, PCA of soil characteristics, CV of soil water
 holding capacity, edge-area ratio).
 "BassettNativeExoticData.mngmt" contains detailed data on seed
 mixes (proportions of functional groups in seed mixes). Both raw and
 standardized ([value-mean]/sd) values for most data.
description: See related dataset Grman et al. 2014. Ecology, 95(8), 2014, p.
 2363 for more info.
description: # Native-exotic richness relationship in Michigan prairies
 [https://doi.org/10.5061/dryad.8gtht76w9](https://doi.org/10.5061/dryad.8gtht76w9) Two datasets. Both raw and standardized ([value-mean]/sd) values for most data.  Both contain exotic and native plant SR (exoticSR.2011, nativeSR.2011) across several prairie restorations, and the residuals from regressing exotic on native SR (resid.site.enrr). This value is a response variable, used to test hypotheses about variation around the correlation of exotic and native SR. 2) And properties of seed mixes used in the restoration: number of species sown (mix.SR, mix.SR.std) and g seeds/m2 sown (g.seeds.m2, dens.std); number of prescribed fires per decade (fire.return, fire.std), and age of restoration in 2011 (age.2011, age.std). "BassettNativeExoticData.csv" contains data on additional factors that influence invasion. *Sources of propagules:* PCA of surrounding land use derived from analyzing proportions of cover types within 500m (landPC1, land.std); recent tillage history, yes or no (land.use2, land.use.binary), edge-to-area ratio of restorations (edge, edge.std); *resources competition:* plant biomass, summed across 10 m-sq plots (biomass.2011, biomass.2011.std), CV of plant biomass across 10 plots (cv.plotbiomass.2011, cvmass.std), mean vegetative cover across 10 plots a (shade, shade.std); PCA of soil characteristics, including texture, moisture, organic matter, nutrients (soilPC1, soil.std); CV of soil water holding capacity (whc.CV, whc.std). "BassettNativeExoticData_mngmt.csv" contains detailed data on seed mixes for 27 sites with detailed seed mix information available, as proportions of four functional groups in seed mixes: C3 graminoids (incl sedges and rushes), C4 grasses, leguminous forbs, non-leguminous forbs. For each group, number of species of that group in seed mix (e.g., mix.C3spp) and seeding rate of that group in g/m2 (e.g., mix.C3). ## Description of the data and file structure As mentioned above, these data were prepared to analyze variation around the native-exotic richness relationship in plants in prairie restorations. Analyses were conducted on the residuals of regressing exotic on native richness (resid.site.enrr), so a positive residual = more natives than expected, and vice versa. Other variables are hypothesized to affect invasion in various ways. ## Code/Software R code in submission is annotated, and will provide additional insights in how to use the data.