Global gradients in intraspecific variation in vegetative and floral traits are partially associated with climate and species richness

Aim Intraspecific trait variation (ITV) within natural plant communities
can be large, influencing local ecological processes and dynamics. Here,
we shed light on how ITV in vegetative and floral traits responds to
large-scale abiotic and biotic gradients (i.e. climate and species
richness). Specifically, we tested if associations of ITV with
temperature, precipitation and species richness were consistent with any
of from four hypotheses relating to stress-tolerance and competition.
Furthermore, we estimated the degree of correlation between ITV in
vegetative and floral traits and how they vary along the gradients.
Location Global. Time period 1975-2016. Major taxa studied Herbaceous and
woody plants. Methods We compiled a dataset of 18,112 measurements of the
absolute extent of ITV (measured as coefficient of variation) in nine
vegetative and seven floral traits from 2,774 herbaceous and woody species
at 2,306 locations. Results Large-scale associations between ITV and
climate were trait-specific and more prominent for vegetative traits,
especially leaf morphology, than for floral traits. ITV showed pronounced
associations with climate, with lower ITV values in colder areas and
higher values in drier areas. The associations of ITV with species
richness were inconsistent across traits. Species-specific associations
across gradients were often idiosyncratic and covariation in ITV was
weaker between vegetative and floral traits than within the two trait
groups. Main conclusions Our results show that, depending on the traits
considered, ITV either increased or decreased with climate stress and
species richness, suggesting that both factors can constrain or enhance
ITV, which might foster plant-population persistence under stressful
conditions. Given the species-specific responses and covariation in ITV,
associations can be hard to predict for traits and species not yet
studied. We conclude that considering ITV can improve our understanding of
how plants cope with stressful conditions and environmental change across
spatial and biological scales.