Tree failure – A natural phenomenon with forensic implications

Abstract

Tree failure, or summer branch drop, refers to situations where large branches or whole trees may unexpectedly drop on unsuspecting victims. On occasion, this involves vehicles impacted by falling overhanging trees or branches. To study this phenomenon further review of the Forensic Science SA, Adelaide, Australia, database and an internet news search were undertaken over a 20 year period from March 2004 to February 2024 for all cases where unexpected accidental deaths in South Australia had been caused by falling branches or trees. There were six cases (age range 12–63 years; average 39 years; M:F 1:2). Three deaths occurred when branches dropped onto vehicles being driven along roads, 2 occurred when entire trees dropped onto the victims (one in windy weather) and 1 was due to a branch drop. Three tree species were identified as a grey box gum tree (Eucalyptus microcarpa), a lemon-scented gum tree (Corymbia citriodora) and a Cottonwood tree (Populus deltoides). The remainder were variants of eucalyptus (gum) trees. Deaths due to tree failures are uncommon and may involve a variety of different tree species with these events not necessarily occurring during high winds or storms. The major findings at autopsy are blunt force injuries.