Etiology of forest dieback areas within the Kaimai Range, North Island, New Zealand

Abstract

Severe forest decline exists in upland areas of the Kaimai Range, North Island, New Zealand. Stand structure of major affected vegetation types is described. As stand dominants are well represented in induced seral vegetation, the overall species composition of the upland forests is not likely to change following decline. Within the decline zone a considerable range of forest damage is found. Characteristic damage types are described including effects on seedling vigour, root system development, and shoot phenology. The decline appears to result from a sequence of natural phenomena. High fog occurrence coincides with the decline zone producing soil waterlogging and generally poor growth conditions. This predisposes the forests to periodic drought damage.