DOI: 10.5061/dryad.0p2ngf2dh
title: Experimental warming drives local grassland plant species loss

description: Climate change poses a growing threat to many ecosystems, including
 grasslands, which are a current priority for conservation due to their
 vulnerability to interacting threats from human activity. North American
 grasslands are expected to experience warmer temperatures and more
 frequent and severe droughts in the coming decades, with potential
 consequences for native biodiversity. We conducted an experiment at Cedar
 Creek Ecosystem Science Reserve, Minnesota, USA, to investigate how
 warming and drought treatments affected grassland plant community
 structure over six years in plots planted with species mixtures. Warming
 consistently reduced plant species richness, with its effects on Shannon
 diversity (which additionally considers species’ relative abundances) and
 dominance varying across years. These warming-by-year interactions were
 likely driven by temporal variability in environmental conditions and
 species-specific responses. Notably, legumes consistently showed positive
 responses to warming. Drought alone had minimal direct effects on species
 richness or diversity but reduced variability in diversity responses over
 time, suggesting greater stability of diversity under drought conditions.
 This study underscores the important role of warming in reducing species
 richness, altering diversity, and reshaping functional group composition
 in grassland ecosystems. While temporal variability influenced the
 magnitude of warming effects on diversity, legumes’ positive responses
 highlight the importance of functional group dynamics in potentially
 buffering against species loss. Long-term experiments that allow
 consideration of interannual variability are essential for improving
 predictions of ecosystem responses and informing adaptive management
 strategies aimed at sustaining biodiversity and ecosystem functioning in
 grasslands. Data structure and concepts: This dataset contains
 experimental and environmental data collected from a multi-year BACD
 (Biodiversity and Climate with Drought) experiment, which applies warming
 and drought manipulation in grassland plots (2017–2022) at Cedar Creek
 Ecosystem Science Reserve. Data are provided in several files capturing
 different community and ecosystem-level responses: species
 presence/absence, species-level biomass (including log-transformed
 values), community-level diversity and dominance indices, functional group
 biomass proportions, daily climate summaries, standardized
 precipitation–evapotranspiration index (SPEI) values, and subplot-level
 soil moisture responses. Data values are primarily continuous (e.g.,
 biomass in g/m², soil moisture in m³/m³, daily temperature and
 precipitation, diversity indices) or categorical (e.g., treatment type,
 year, subplot). The dataset is broadly reusable for meta-analyses of
 global change experiments, ecological modeling and parameterization, and
 teaching applications. No sensitive information is included, and no legal
 or ethical restrictions apply to reuse beyond standard citation and
 attribution.
description: # Experimental warming drives local grassland plant species loss ##
 Overview This dataset is associated with the manuscript by **Anderson and
 Isbell (2025)** entitled: &gt; *"Experimental warming drives local
 grassland plant species loss"*\ &gt; *Journal of Ecology, 2025* It
 contains experimental and environmental data collected from a multi-year
 **BACD (Biodiversity and Climate with Drought) experiment** which applied
 warming and drought manipulations in grassland plots (2017–2022) at
 **Cedar Creek Ecosystem Science Reserve**. Data are provided in several
 files capturing different community- and ecosystem-level responses: *
 species presence/absence * species-level biomass (including
 log-transformed values) * community-level diversity and dominance indices
 * functional group biomass proportions * daily climate summaries *
 standardized precipitation–evapotranspiration index (SPEI) values *
 subplot-level soil moisture responses Data values are primarily
 **continuous** (e.g., biomass in g/m², soil moisture in m³/m³, daily
 temperature and precipitation, diversity indices) or **categorical**
 (e.g., treatment type, year, subplot). The dataset is broadly reusable
 for: * meta-analyses of global change experiments * ecological modeling
 and parameterization * teaching applications No sensitive information is
 included, and no legal or ethical restrictions apply to reuse beyond
 standard citation and attribution. --- ## Files and Contents ### 1.
 `SpeciesPresenceAbsence_2017_22.csv` * Presence/absence of each species in
 subplots across all years and treatments. * **Experiment structural
 variables include:** * `Year`: calendar year in which the subplot was
 sampled * `HeatTrt`: experimental warming (+heat) treatment with two
 levels: "Heated" and "Control" applied at the subplot
 level * `WaterTrt`: experimental drought (-water) treatment with two
 levels: "Drought" and "Control" applied at the subplot
 level * **Response variables include:** * `Species`: species occurring
 under a given treatment and year combination * `Subplots`: number of total
 subplots in which that species occurred under a given treatment and year
 combination ### 2. `MeanSpsBiomass_TreatmentYear.csv` * Species-level
 biomass data summarized by treatment and year. * Includes means, standard
 errors, standard deviations, and log-transformed values. * **Units:**
 biomass in g/m² * **Experiment structural variables include:** * `Trtmt`:
 Combined HeatTrt and WaterTrt columns * `HeatTrt`: experimental warming
 (+heat) treatment with two levels: "Heated" and
 "Control" applied at the subplot level * `WaterTrt`:
 experimental drought (-water) treatment with two levels:
 "Drought" and "Control" applied at the subplot level *
 `Year`: calendar year in which the subplot was sampled * **Response
 variables include:** * `Species`: species occurring under a given
 treatment and year combination * `FunctionalGroup`: functional group
 designation for a given species (legume, forb, C3 grass, or C4 grass) *
 `TotalBiomass.g.m2_mean`: total biomass in g/m² averaged by species,
 treatment, and year * `TotalBiomassLog_mean`: log-transformed values of
 TotalBiomass.g.m2_mean * `TotalBiomass.g.m2_sd`: standard deviation (SD)
 of total biomass in g/m², grouped by species, treatment, and year *
 `TotalBiomass.g.m2_sd`: standard deviation (SD) of log-transformed total
 biomass, grouped by species, treatment, and year * `TotalBiomass.g.m2_se`:
 standard error (SE) of total biomass in g/m², grouped by species,
 treatment, and year * `TotalBiomass.g.m2_se`: standard error (SE) of
 log-transformed total biomass, grouped by species, treatment, and year ###
 3. `CommunityLevelDataClean_2017_22.csv` * Community-level response
 variables and treatment design information. * **Experiment structural
 variables include:** * `Plot`: unique non-consecutive ID numbers
 associated with each plot. Each plot contains four subplots * `Subplot`:
 letter abbreviations corresponding to the locations of subplots within
 each plot, including "NE" (northeast), "NW"
 (northwest), "SE" (southeast), and "SW" (southwest) *
 `Year`: calendar year in which the subplot was sampled * `HeatTrt`:
 experimental warming (+heat) treatment with two levels: "Heated"
 and "Control" applied at the subplot level * `WaterTrt`:
 experimental drought (-water) treatment with two levels:
 "Drought" and "Control" applied at the subplot level *
 **Response variables include:** * `RichnessTrt`: initial planted richness
 (16 species used here) * `Dq0`: species richness * `Dq1`: Shannon
 diversity (Hill number q = 1) * `Dq2`: inverse Simpson diversity (Hill
 number q = 2) * `BP`: Berger-Parker dominance index * `invSimpEven`:
 evenness (based on inverse Simpson index) * `p.Ag`: proportional biomass
 of Big bluestem (*Andropogon gerardii*), the dominant grass species in our
 experiment * `biomass`: a constant string of repeating 1s, denoting the
 sum of all plant functional group biomass proportions * Proportional
 biomass of plant functional groups: legumes (`LegumeBiomass`), C3 grasses
 (`C3Biomass`), C4 grasses (`C4Biomass`), and forbs (`ForbBiomass`). ### 4.
 `e080_DailyClimateSummary.csv` * Daily maximum/minimum temperature and
 precipitation from the on-site Cedar Creek weather station. * **Units:**
 °F (temperature), in (precipitation) * **Variables:** * `Date`: date of
 measurement in MM/DD/YYYY format * `MaxTemp.degF.`: Maximum daily
 temperature in °F   * `MinTemp.degF.`: Minimum daily temperature in °F   *
 `Precip.inches.`: Total daily precipitation in inches * `TempSource`:
 Source of daily temperature data   * `PrecipSource`: Source of daily
 precipitation data      ### 5. `SPEI_data.csv` * Standardized
 Precipitation–Evapotranspiration Index values calculated for the study
 site. * **Variables:** * `Date`: date of measurement in MM/DD/YYYY format
 * `SPEI`: four-month SPEI value for our field site corresponding to date *
 `Year`: calendar year corresponding to date * `Month`: month (numeric)
 corresponding to date * `Day`: day of the month (numeric) corresponding to
 date ### 6. `SoilMoisture_2017-22_Summarized.csv` * Subplot-level soil
 moisture summaries. * Includes experimental design and treatment-response
 information. * **Columns:** * `Exp`: experiment identifier * `LTERYEAR`:
 year of data collection * `Plot`: unique plot ID number (nonconsecutive) *
 `response`: soil moisture response to warming, drought, or both (relative
 to controls) * `value`: volumetric water content (m³/m³), expressed as
 response ratios * `YrFac`: year (factor) * `Trtmt`: two-letter identifier
 for treatment combination * `Subplot`: letter abbreviations corresponding
 to the locations of subplots within each plot, including "NE"
 (northeast), "NW" (northwest), "SE" (southeast), and
 "SW" (southwest) * `sp`: combined plot/subplot identifier ### 7.
 `Anderson_Isbell_2025_Journal-of-Ecology_Code.R` * Complete code required
 to perform model selection and generate figures --- ## Data Collection *
 **Biomass harvests:** Annual clip-strip (0.1 × 1.5 m) harvests from each
 subplot, sorted to species, dried, and weighed. * **Soil moisture:**
 Measured monthly (May–September) at 5 subplot locations, using a ProCheck™
 probe (Decagon Devices). Only morning measurements (before 11 AM) were
 retained. * **Climate:** Daily precipitation and temperature recorded from
 an on-site weather station; SPEI calculated for growing seasons. --- ##
 Data Values * **Biomass:** g/m² * **Soil moisture:** volumetric water
 content (m³/m³) * **Temperature:** °C * **Precipitation:** mm *
 **Diversity indices:** unitless (Hill numbers, Shannon, Simpson,
 Berger-Parker, evenness) * **Presence/absence:** binary (0/1)