Native range climate influences nonstructural carbohydrate storage in oak species growing in a common garden.

Global climate change and related environmental stress threaten the survival of long-lived tree species. To ensure survival in increasingly unfavorable environments, trees need to either acclimate through phenotypic plasticity, adapt via genetic differentiation, or migrate to more favorable climates altogether. Nonstructural carbohydrate (NSC) storage is a critical trait that supports proper metabolic function in plants and has been shown to prolong their survival in the face of stress. However, relatively few studies have explored local adaptation of NSC storage, with none to our knowledge focusing on oaks, an abundant and ecologically important genus primarily across the Northern Hemisphere. Here, we used a common garden of oak species to assess whether NSC storage is locally adapted by exploring whether species' native range climate influences NSC storage in the stem. We found that the proportion of soluble sugars, the proportion of starch, and starch concentration were influenced by native range temperature, such that species from hotter regions had a larger proportion of soluble sugars, smaller proportion of starch, and lower starch concentration than species from colder regions. These correlations suggest that some NSC traits (i.e., proportion of sugars/starch) are genetically controlled in the genus Quercus. Our study has implications for how different oak species may respond to and survive under environmental stress and changing climates.