Functional traits can explain coordinated seedling responses to drought and freezing stress

Authors: Larson, Julie Elizab; BUTTERFIELD, BRADLEY - Northern Arizona University; MUNSON, SETH - Us Geological Survey (USGS); NEUHAUS, DYLAN - University Of Central Arkansas; Copeland, Stella

Submitted to: Functional Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: Environmental stress limits recruitment. Species may have coordinated or contrasting response strategies to multiple stressors, but they are vastly underexplored at the earliest stages of plant life. Across 49 coexisting species, we found 2-fold variation in seedling drought and freezing tolerance. Overlapping trait drivers suggest some common strategies to limit desiccation stress, but tradeoffs between freezing tolerance and avoidance via seed germination delay emphasize the viability of multiple strategies in common environments. Traits explained stress tolerance better than climate niche, which may have failed to reflect recruitment-specific conditions shaping occurrence at finer spatiotemporal scales. Our results demonstrate the potential power of traits, more than climate or evolutionary history, to inform patterns and processes of recruitment in stressful environments.

Technical Abstract: Plant establishment is often the greatest demographic bottleneck in drylands globally, limiting ecosystem restoration and recovery. Seedling vulnerability to drought and freezing are presumed barriers, yet we understand little about patterns and predictors of stress tolerance across species at early life stages. There may be multiple mechanisms of resistance to different stressors that are shaped and by the shared traits, climate or evolutionary histories of species. We asked whether seed and seedling functional traits explain variation in drought and freezing tolerance across common plant species in US cold deserts, uniquely, or in conjunction with species’ climate niches or phylogenetic relatedness. Drought and freezing tolerance were moderately correlated, with an overlap in the trait dimensions linked to each. Drought tolerance was best explained by large seed mass and rapid root elongation, while freezing tolerance was additionally linked to low minimum temperature thresholds for root elongation. In contrast, freezing-intolerant species tended to require warmer germination temperatures, signaling an avoidance strategy. Phylogenetic relatedness explained unique variation in drought tolerance attributed to drought-tolerant grasses, while species’ climate niches partially explained freezing tolerance in conjunction with traits but were poor predictors overall. We conclude that seedling tolerance of multiple stressors are linked by the common, early advantages of some functional traits, including large mass and rapid root growth. At the same time, coexisting species have alternative strategies mediated by additional traits and adaptations that should expand recruitment potential over space and time in diverse and dynamic landscapes.