Experimental warming drives local grassland plant species loss

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.