LAUSR

Climate change is pushing species outside of their evolved tolerances. Plant populations must acclimate, adapt, or migrate to avoid extinction. However, because plants associate with diverse microbial communities that shape their phenotypes, shifts in microbial associations may provide an alternative source of climate tolerance. Here, we show that tree seedlings inoculated with microbial communities sourced from drier, warmer, or colder sites displayed higher survival when faced with drought, heat, or cold stress, respectively. Microbially mediated drought tolerance was associated with increased diversity of arbuscular mycorrhizal fungi, whereas cold tolerance was associated with lower fungal richness, likely reflecting a reduced burden of nonadapted fungal taxa. Understanding microbially mediated climate tolerance may enhance our ability to predict and manage the adaptability of forest ecosystems to changing climates. Description Editor’s summary As sessile organisms, plants have limited ability to move in response to climate change. However, the microbial communities that help plants access soil nutrients may also increase their tolerance to climate stress. Using field and laboratory experiments, Allsup et al. showed that soil microbe communities sourced from colder or drier sites increased the survival of inoculated tree seedlings exposed to cold winters or drought, respectively (see the Perspective by Afkhami). These findings suggest greater potential resilience for trees and highlight the importance of species interactions in determining their response to climate change. —Bianca Lopez Microbial communities sourced from more extreme climates can help tree seedlings tolerate cold and drought.