Phenotypic traits and environment strongly predict seedling survival for
seven co-occurring Great Basin plant taxa growing with invasive grass
Abstract
Trait-environment correlations can arise from local adaptation and can
identify genetically and environmentally appropriate seeds for
restoration projects. However, anthropogenic changes can disrupt the
relationships between traits and fitness. Finding the best seed sources
for restoration may rely on describing plant traits adaptive in
disturbed and invaded environments, recognizing that while traits may
differ among species and functional groups, there may be similarities in
the strategies that increase seedling establishment. Focusing on three
grass genera, two shrub species, and two forb genera, we collected seeds
of all taxa from 16 common sites in the sagebrush steppe of the western
United States. We measured seed and seedling characteristics, including
seed size, emergence timing, and root and shoot traits, and compiled a
suite of environmental variables for each collection site. We described
trait-environment associations and asked how traits or environment of
origin were associated with seedling survival in invaded gardens.
Sampling seven taxa from the same sites allowed us to ask how
trait-environment-performance associations differ among taxa and whether
natural selection favors similar traits across multiple taxa and
functional groups. All taxa showed trait-environment associations
consistent with local adaptation, and both environment of origin and
phenotypic traits predicted survival in competitive restoration
settings, with some commonalities among taxa. Notably, rapid emergence
and larger seeds increased survival for multiple taxa. Environmental
factors at collection sites, including lower slopes (especially for
grasses), greater mean annual temperatures (especially for shrubs and
forbs), and greater precipitation seasonality were frequently associated
with increased survival. We noted one collection site with high seedling
survival across all seven taxa, suggesting that conditions within some
sites may result in selection for traits that increase establishment for
multiple species. Thus, choosing native plant sources with the most
adaptive traits, along with matching climates, will likely improve the
restoration of invaded communities.