Drought Sensitivity and Resilience of Oak-Hickory Stands in the Eastern United States

Forest composition in the eastern United States (US) has been shifting from an oak-hickory to maple-beech assemblage, but whether there are species-specific differences within these oak-hickory stands in their responses and recovery from drought remains unclear. Here, we examined drought responses and resilience derived from radial growth of 485 co-occurring Carya ovata and Quercus alba individual trees at 15 forests in the eastern US. Water availability over the growing season (May to August) of the current year controls growth variability of both C. ovata and Q. alba. Drought that occurred in June caused the greatest growth reduction for both species while interspecific differences inof drought-induced growth reduction was found in July, where Q. alba experienced stronger reduction than C. ovata. Both species are resilient to early growing season drought, but late growing season drought caused larger drought legacy effects for Q. alba. The increasing drought frequency and intensity will have a more prominent impact in oak-hickory stands in the eastern US. The species composition of a forest along with species-specific responses and recovery is likely to be a critical control on forest productivity and species abundance.

Automated summary

Forest composition in the eastern US is shifting from oak-hickory to maple-beech. Both Carya ovata and Quercus alba show responses to water availability during the growing season, with drought in June causing the greatest growth reduction for both species. However, Q. alba experiences stronger reduction than C. ovata in July. Late growing season drought has a larger impact on Q. alba's resilience. Increasing drought frequency and intensity will have a significant impact on oak-hickory stands in the eastern US.