A 31-year-old man was taken to Dunedin Hospital from Waipori forest, near Lake Mahinerangi, by the Otago Regional Rescue helicopter on Thursday after a logging accident.
A St John ambulance spokeswoman said the forestry worker received pelvic injuries.
City Forests chief executive officer Grant Dodson, of Dunedin, said the man was working in Waipori Forest when he was struck by a tree.
Mr Dodson visited the scene yesterday.
City Forests would run an internal investigation and an independent report would also be prepared. Occupational Health and Safety had been notified.
Investigations would be completed next week.
"This is an unfortunate accident . . . which would be in the 'serious' category.
Our company and crews run comprehensive health and safety programmes and we will investigate thoroughly to see which lessons need to be learned to improve safety in future."
