THE LATE PLEISTOCENE AND HOLOCENE VEGETATION HISTORY OF TARANAKI, NORTH-ISLAND, NEW-ZEALAND

Pollen diagrams are presented from four lowland Taranaki sites which c ollectively span the last 13 000 years. At c. 13 000 years ago, lowlan d Taranaki was occupied by an open grassland in which shrubland was re stricted and forest scarce. Beginning c. 12 500 years ago, there was a rapid transition, essentially complete by 11 000 years ago, to tall c omplex conifer/broad-leaved forest in which Prumnopitys taxifolia was the most abundant tall tree. By 9500 years ago, the last of the cool t emperate forest elements (most notably Nothofagus menziesii and Liboce drus bidwillii) had been eliminated from the forest, and Dacrydium cup ressinum had supplanted Prumnopitys taxifolia as the most abundant tal l podocarp tree. In coastal regions, Ascarina lucida and Dodonaea visc osa were abundant. From 5000 years ago, Ascarina lucida and Dodonaea b ecame much less common, and Ascarina lucida is now nearly extinct in t he Taranaki region. Knightia excelsa and Lagarostrobos colensoi spread during the late Holocene. The early grassland phase suggests harsh cl imatic conditions, perhaps characterised by severe drought and frost, although annual average temperatures cannot have been much more than 4 -5 degrees C below those of the present. The subsequent spread of tall conifer/broad-leaved forest indicates a prolonged and apparently unin terrupted climatic amelioration. Early Holocene conditions seem to hav e been close to those of the present, although climatic variability an d extremes were much reduced. From 9500 years ago to the present, clim atic change was slight, but there is some indication of increasing sum mer water deficits and increased disturbance to the vegetation after 5 000 years.