Can local climate change drive local extinction? While the answer to this question has far reaching population-, community-, and ecosystem-level consequences, we have a limited understanding of the potential for, and mechanisms by which, predicted shifts in microclimate will drive changes in population viability. Here, to directly study causal links between local climate change and local extinction, we coupled 26 years of experimental warming with fine-scale demographic analysis and experimental seed introductions of a native, mountain wildflower (Androsace septentrionalis, Primulaceae).
Results/Conclusions
We found that experimental warming caused a precipitous decline in A. septentrionalis seedling and adult plant abundance, resulting in aboveground population sizes very close to zero. We also found that warming purged another, more elusive component of plant population size: belowground seed banks. Local warming caused these above- and belowground declines by stimulating seedling emergence, increasing seedling mortality, and decreasing both adult survival and fecundity. These effects, spread across the A. septentrionalis life cycle, resulted in strikingly low population growth rates that explain observed population cashes and predict inevitable local extinction. Because A. septentrionalis has a short generation time relative to most other sub-alpine and alpine plant species, it is likely among the first to reveal population-level responses to environmental change. A. septentrionalis may therefore be a “canary in a coal mine” – its precipitous decline a warning of potentially widespread, warming-induced local extinctions across mountain plant communities.