Multiyear defoliations in southern New England increases oak mortality

After decades of multiyear defoliation episodes in southern New England, Lymantria dispar (previously gypsy moth) populations diminished with the appearance L. fungus 1989. Multiyear defoliations did not occur again until 2015–2018. To assess impact return defoliations, we examined 3095 oaks on 29 permanent study areas Connecticut and Rhode Island that were established at least 11 years before latest outbreaks. Pre-defoliation stand-level oak mortality averaged 2% (3-year basis). Post-defoliation differ between managed unmanaged stands but was much higher severely defoliated (36%) than moderate (7%) or low to no (1%). individual trees differed among species, lower for larger diameter stands. plots similar pre-defoliation levels. Following white (Quercus alba L.) northern red rubra black (Q. velutina Lam.). There weak evidence elevated basal area following severe defoliation. Natural resource managers should assume survived earlier will survive future outbreaks, possibly because are older.