DOI: 10.5061/dryad.6q573n5vt
title: Lasting signature of planting year weather on restored grasslands

description: Ecological restoration — the rebuilding of damaged or destroyed ecosystems
 — is a critical component of conservation efforts, but is hindered by
 inconsistent, unpredictable outcomes. We investigated a source of this
 variation that is anecdotally suggested by practitioners, but for which
 empirical evidence is rare: the weather conditions during the first
 growing season after planting. The idea of whether natural communities
 face long-term consequences from conditions even many years in the past,
 called historical contingency, is a debated idea in ecological research.
 Using a large dataset (83 sites) across a wide geographic distribution
 (three states), we find evidence that precipitation and temperatures in
 the planting year (2-19 years before present) affected the relative
 dominance of the sown (native target species) and non-sown (mostly
 non-native) species. We find strong support for lasting planting year
 weather effects in restored tallgrass prairies, thereby supporting the
 historically contingent model of community assembly in a real-world
 setting.
description: We surveyed 83 restored prairie sites in Illinois, Indiana, and
 Michigan between 18 July-16 September 2016. In each site, we established a
 50 m transect in a random orientation. For Michigan and Illinois sites,
 transects were centered on the approximate centroid of the site; for
 Indiana sites, which were much larger, transects were placed inside the
 boundary of visible edge effects. At 5- or 10- m intervals (for Michigan
 and Illinois/Indiana sites, respectively), we placed a 1 m x 1 m quadrat
 frame on the ground and visually quantified the percent cover of each
 species present. We surveyed 5 plots per site in Indiana and Illinois, and
 10 plots in Michigan (for compatibility with another project outside the
 scope of this manuscript). In addition, we systematically walked a 20 m x
 50 m area centered on the transect and recorded additional species
 observed. We collected two soil cores at 5 m intervals
 along each transect using an Oakfield soil probe (20 total per site, 2 cm
 × 20 cm soil cores). Soil cores were homogenized at each site. We
 determined soil water holding capacity by saturating field samples and
 then drying for 72 hours at 105°C and calculating the proportional
 difference in saturated wet weight and oven‐dried weight. Air-dried
 samples were also analyzed for a variety of soil properties including pH,
 percent organic matter, percent clay/silt/sand, and soil nutrients (S, P,
 Ca, Mg, K, Na, B, Fe, Mn, Cu, Zn, and Al) by Brookside Laboratories (New
 Knoxville, OH, USA). To reduce the potential number of predictor
 variables, we conducted a principal components analysis on the soils data
 using prcomp in R with each variable scaled due to large variation the
 concentrations of soil nutrients. For later analyses, we used the first
 principal component, which accounted for 40.5% of the variation in the
 soils data and was associated with higher percent organic matter, higher
 water holding capacity, higher clay content, higher silt content, higher
 nutrients (except Zn, Fe, and P), and less sand.  We
 worked with land managers at each site to compile information about the
 restored prairies, including the date of planting, prescribed fire
 history, and the relative abundance (by weight) of each species sown in
 the initial planting. We used 30-arcsec (approximately 800 m) spatially
 gridded PRISM Climate Data to compile interpolated information on the
 daily precipitation accumulation and minimum and maximum temperature in
 the first growing season for each site based on its latitude and
 longitude. We used these data to calculate cumulative growing degree days
 (base 10°C); this temperature-based unit is often used in agronomic
 systems to predict development of plants and other species. We calculated
 cumulative precipitation and averages related to temperature and
 precipitation at various stages throughout the growing season.
 To characterize weather conditions at the time of planting we
 focused on eleven variables that we hypothesized would influence the
 germination and establishment of plant communities during the first
 growing season of prairie restoration: spring temperatures (degree day
 accumulation March 1 – June 1), spring precipitation accumulation (March 1
 – June 1), summer temperatures (degree day accumulation June 1 – September
 1), summer precipitation accumulation (June 1 – September 1), full growing
 season temperatures (degree day accumulation March 1 – September 1), full
 growing season precipitation accumulation (March 1 – September 1), the
 hottest month (maximum degree days accumulated in a 30-day period), the
 longest drought (maximum consecutive days without a precipitation event),
 the driest month (minimum precipitation in a 30-day period, in mm),
 average low temperature (March 1 – September 1, °C), and the average
 monthly precipitation (March 1 – September 1, mm). We focused on this set
 of variables owing to the reported roles of temperature and precipitation
 for plant establishment dynamics[28,71] and for year effects broadly.
 Because many of these variables were correlated, we conducted a Principal
 Components Analysis to determine composite metrics with which to test our
 hypotheses. We focused on the first three axes (out of eleven total) that
 together accounted for 74.2% of the variation in weather data. 
description: Also included in this upload are:
 "Groves-Bauer-Brudvig-2020-Seeds-Density.csv", which
 includes the seed mix data for the sites, that we collected from
 pracitioners, and our R script,
 "R.SCRIPT-Groves-Bauer-Brudvig-2020.R" used for data analyses
 and to produce figures for the paper. The variables
 included in the
 <strong>"MASTER-DATA"</strong> dataset, and any
 additional notes about their origins, are as follows:
 <strong>Site</strong>: A unique descriptor for each
 restored prairie site.
 <strong>Landscape</strong>: Refers to whether the
 site was part of our Illinois (McHenry County Conservation District),
 Indiana (The Nature Conservancy's Kankakee Sands), or Michigan
 (private prairies restored by Native Connections, Three Rivers, MI);
 labeled as "MCCD", "KSands", or "MI",
 respectively.
 <strong>First_Growing_Season</strong>: The first
 growing season after the prairie was planted.    
 <strong>Age_2016</strong>: The number of growing
 seasons that had passed since planting, as of 2016 when plant surveys were
 conducted.     <strong>Biomass</strong>:
 Total (dried) biomass collected from 5 1x1m plots. Plots with missing
 values ("NA") were mowed after plant community surveys but
 before biomass collection was able to take place.    
 <strong>Last.Burn: </strong>The number of years since
 the prairie last had a prescribed fire. If a site had never burned, was
 set to equal "Age_2016".     Rolling
 planting-year weather metrics, based on either degree day accumulation, or
 precipitation accumulation, starting March 1: <strong>Apr1.dd.accum,
 Apr1.precip.accum, May1.dd.accum,
 May1.precip.accum, Jun1.dd.accum, Jun1.precip.accum, Jul1.dd.accum,
 Jul1.precip.accum, Aug1.dd.accum, Aug1.precip.accum, Sep1.dd.accum,
 Sep1.precip.accum, summer.dd.accum, summer.precip.accum, Oct1.dd.accum,
 Oct1.precip.accum: </strong>For example, Apr1.dd.accum is the number
 of planting degree days by April 1 of the first growing season.
 "summer.dd.accum" is Jul 1 - Oct 1.
 Additional metrics include: <strong>max.month.dd.accum,
 max.mean.month.precip, max.tot.month.precip, min.month.precip, high.temp,
 avg.high.temp, low.temp, avg.low.temp, avg.mon.rain.days,
 max.days.no.precip, avg.temp, spring.temp, summer.temp  
 </strong>
 <strong>Mix.Richness: </strong>The species richness
 of the seed mix sown to restore the site. Based on the
 plant community surveys, we tallied the species richness (of all species,
 sown species only, and non-sown species only) for both the 1x1 m plots
 ("Richness.Plots") as well as for the larger site walkthrough
 ("Richness.Walkthru"). These two added together (without
 repeating species) is
 "Richness.Total.": <strong>Site.Richness.Walkthru,
 Site.Richness.Plots, Site.Richness.Total, Sown.Richness.Plots,
 Sown.Richness.Total,
 Nonsown.Richness.Plots, Nonsown.Richness.Total</strong>
 <strong>Percent.of.Mix.Sp.Present: </strong>Percentage of species in the seed mix (Mix.Richness) present at the site. <strong>Mean.Plot.Richness: </strong>Instead of total plot richness, the average across all plots. <strong>Num.Plots: </strong>The number of plots surveyed at each site, should be 10 for Michigan and 5 for Illinois and Indiana sites. <strong>Mean.Sown.Cover, Mean.Nonsown.Cover: </strong>Percent cover of sown and non-sown species at the 1x1m plot level. Can equal &gt;100% because of overlapping plants. <strong>Mix-Veg.BCdissim: </strong>Bray-Curtis dissimilarity between the composition of the seed mix and the standing plant community. <strong>Mean.ANDGER.Cover, Mean.SOLCAN.Cover, Mean.SCHSCO.Cover, Mean.SORNUT.Cover, Mean.POAPRA.Cover, Mean.Rubus.Cover, Mean.RATPIN.Cover, Mean.DESCAN.Cover, Mean.ELYCAN.Cover, Mean.MONFIS.Cover: </strong>Percent cover of the most common sown and non-sown species, Andropogon gerardii, Solidago canadensis, Schizachyrium scoparium, Sorghastrum nutans, Poa pratensis, Rubus sp. Ratibida pinnata, Desmodium canadense, Elymus canadensis, and Mondarda fistulosa. <strong>pH, Organic.Matter.percent, S.ppm, P.mg.per.kg, Ca.mg.per.kg, Mg.mg.per.kg, K.mg.per.kg, Na.mg.per.kg, B.half.detection, Fe.mg.per.kg, Mn.mg.per.kg, Cu.half.detection, Zn.mg.per.kg, Al.mg.kg, Clay.percent, Silt.percent, Sand.percent, Water.Holding.Capacity: </strong>Soils data.