Data for: Local adaptation of switchgrass drives trait relations to yield and differential responses to climate and soil environments

Switchgrass, a potential biofuel crop, is a genetically diverse species
with phenotypic plasticity enabling it to grow in a range of environments.
Two primary divergent ecotypes, uplands and lowlands, exhibit trait
combinations representative of acquisitive and conservative growth
allocation strategies, respectively. Whether these ecotypes respond
differently to various types of environmental drivers remains unclear but
is crucial to understanding how switchgrass varieties will respond to
climate change. We grew two upland, two lowland, and two
intermediate/hybrid cultivars of switchgrass at three sites along a
latitudinal gradient in the central United States. Over a 4-year period,
we measured plant functional traits and biomass yields and evaluated
genotype-by-environment (G´E) interaction effects by analyzing switchgrass
responses to soil and climate variables. We found substantial evidence of
G´E interactions on biomass yield, primarily due to deviations in the
response of the southern lowland cultivar Alamo, which produced more
biomass in hotter and drier environments relative to other cultivars.
While lowland cultivars had the highest potential for yield, their yields
were more variable year-to-year compared to other cultivars, suggesting
greater sensitivity to environmental perturbations. Models comparing soil
and climate principal components as explanatory variables revealed soil
properties, especially nutrients, to be most effective at predicting
switchgrass biomass yield. Also, conservative plant traits such as high
stem mass and tiller height became increasingly positively associated with
biomass yield at lower latitudes where the climate is hotter and drier,
regardless of ecotype. Lowland cultivars, however, showed a greater
predisposition to exhibit these conservative traits. These results suggest
switchgrass trait allocation trade-offs that prioritize aboveground
biomass production are more tightly associated in hot, dry environments
and that lowland cultivars may exhibit a more specialist life strategy
relative to other cultivars. Altogether, this research provides essential
knowledge for improving the viability of switchgrass as a biofuel crop.