Intraspecific variation has been shown to compose a quarter to a third of total functional trait variation in plant communities. However, the degree to which this represents heritable variation, and the environmental drivers of that variation, have been relatively poorly studied. Better understanding within-species variation, especially of poorly studied belowground traits, may help clarify whole plant economics and drivers of broad-sense heritability. Because of the extensive ranges of many western US grasses, heritable, functional variation may arise within a species in response to local factors, such as climate. In a greenhouse common garden experiment with multiple populations each of 9 different, broadly distributed perennial grass species, we addressed three questions: (1) to what extent is functional trait variation heritable, (2) to what extent does heritable trait variation vary predictably as a function of source climate, and (3) do all species exhibit similar trait-environment relationships.
Most traits exhibited broad-sense heritability at the population level. The majority of traits exhibited significant, albeit moderate to weak, correlations with climate. Annual temperature exhibited the most consistent trait-environment relationships within species (i.e. intraspecific trait-temperature relationships were similar across species), whereas the nature of other trait-environment relationships tended to be more variable. We discuss the implications of this work in the context of local adaptation and responses to environmental change, as well as the utility of intraspecific trait-environment relationships for seed source selection in restoration activities, particularly in the American West.