Fire, forest regeneration and links with early human habitation: Evidence from New Zealand

Abstract

New Zealand forests burn less frequently than tussock grasslands, heath or shrublands. Species composition, past disturbance and stand condition determine inflammability and fuel load, and consequent fire intensity and spatial extent. Before people arrived, fires were ignited by lightning during drought years on the eastern sides of both islands. Volcanism occurring every 300-600 years was associated with fires in the central North Island. A review of radiocarbon-dated charcoal from the eastern South Island, and of evidence for fire in pollen profiles from the North Island, provide the basis for an assessment of fire frequency. Forest fires have occurred on both New Zealand's islands throughout the Holocene at least every few centuries, until the last millennium when frequency increased. The 'return time' of fire at any one place in the forested landscape was probably one or two millennia. Burned areas usually succeeded to forest again before the next inflagration. Consequently fire adaptation is infrequent in the New Zealand flora, and Polynesian forest clearance was rapid and largely permanent. There is an indication of an increase in fire frequency in the late Holocene, and a clear signal associated with people approx. 700 years BP. Separating the earliest anthropogenic fires from the background level of natural burning will be difficult without additional evidence.