Scott Hammond/Stuff Old growth patches, like those at Marlborough’s Onamalutu Scenic Reserve, are the last bastion of ancient forests, says a botany professor. An ancient forest with a lineage that stretches back to when New Zealand was part of the supercontinent Gondwana has been losing trees to erosion for years. Podocarp trees at Marlborough’s Onamalutu Scenic Reserve have been lying in the Ōhinemahuta River since July, but they are just the latest to fall victim to the riverbank’s ongoing erosion. Emails seen by Stuff show the Department of Conservation was looking into fallen trees in the reserve in 2018, as a result of flood events “over the last couple of years”.