The Polynesian Settlement of New Zealand in Relation to Environmental and Biotic Changes

Polynesian settlement of New Zealand (c. 1000 yr B.P.) led directly to the extinction or reduction of much of the vertebrate fauna, destruction of half of the lowland and montane forests, and widespread soil erosion. The climate and natural vegetation changed over the same time but had negligible effects on the fauna compared with the impact of settlement. The most severe modification occurred between 750 and 500 years ago, when a rapidly increasing human population, over-exploited animal populations and used fire to clear the land. Human predation, and destruction of forest habitat eliminated the moa and other large ground birds. Moa appear to have been more abundant in drier conifer-broadleaved forest on fertile lowland sites, than in wetter areas and in cool upland forests. Most forests remaining today are wet mountain land communities, and may never have experienced severe browsing pressure until Europeans introduced browsing mammals. The moderate amount of browsing pressure exerted in them by moa may have been insufficient for the plants to develop browsing adaptations capable of coping with the impact of mammals. Knowledge of these climatic, physical and cultural forces which shaped the biota of present day New Zealand are important for understanding how to manage the remaining estate.