A HISTORY OF KAIPARORO CLEARING AND THE LIMITS OF NOTHOFAGUS IN THE NORTHERN TARARUA RANGE, NEW-ZEALAND

Kaiparoro clearing is a 40 ha enclave of tussock grassland within fore st, straddling a rounded peneplain remnant in the northern Tararua Ran ge. The grassland occurs at an unusually low altitude compared with ot her North Island red tussock grasslands. Charcoal and pollen from a pe at bog suggests that fire created the clearing and helped maintain ope n vegetation throughout its 3500+ year history. There appear to be no edaphic constraints on forest occupation of most of the site. Before t he clearing was created, tussock grasses were probably confined to sma ll riparian peat bogs within low forest on the peneplain surface. Rate s of shrub invasion of the tussock clearing by Dracophyllum longifoliu m, Leptospermum scoparium, and Olearia colensoi are slow. A fire retur n-period of <400 years would be sufficient to perpetuate the open or n on-forest vegetation. Kaiparoro coincides with the modern-day distribu tional limits of Nothofagus in the northern Tararua Range. The pollen record indicates that Nothofagus has had a delayed population growth t here in the Holocene relative to the main population centre further so uth. Similar trends for Nothofagus at other provincial limits in its d istribution are evident elsewhere in New Zealand. Pollen results from Kaiparoro and similar sites adjacent to Nothofagus boundaries, suggest that Nothofagus in non-competitive under humid, mild, low-insolation climates.