Timing of bud burst is associated with climate of maternal origin in quercus lobata progeny in a common garden

Deciduous trees leaf out in the spring beginning with bud burst. Proximally, the timing of that process is triggered by temperature, but natural selection on bud burst timing may have acted in local populations through additional factors, such as frost damage, insect herbivores and fungal pathogens. Valley Oak, Quercus lobata Née, is a deciduous California endemic tree species that shapes the ecosystems where it is found. We examined the phenology of spring bud burst in trees collected from 674 maternal families across the species range, grown in two replicate common gardens. We found significant differences among the families for timing of bud burst, and also found that onset of bud burst differed between gardens, presumably due to climate. The differences among families were associated with the climate of origin where the trees were collected suggesting that some extent of genetic differentiation in bud burst is due to local adaptation. Given predicted changes in climate in California for the future, understanding patterns of bud burst will help inform the selection of seed sources for reforestation efforts.