Abstract:
Fine resolution pollen analysis shows that the late-glacial (c. 13 000-10 700 B.P.) vegetation of the Ohakune-Horopito area was dominated by Prumnopitys taxifolia, indicating a cooler and probably drier climate than the present. Around 10 700 B.P., Dacrydium cupressinum replaced Prumnopitys taxifolia as the forest dominant, and tree ferns and hardwood trees expanded, suggesting a change to warmer or wetter conditions. Around 5800-6300 B.P., Dacrydium cupressinum and tree ferns declined, Prumnopitys taxifolia regained some of its former dominance, and hardwood species continued to expand, suggesting a change to more variable conditions. Immediately following the Taupo Tephra eruption of 1718 B.P., Libocedrus bidwillii expanded at Gibsons' Swamp. The eruption may have facilitated a regional expansion of this species which was apparently already underway as a result of a climate change to stormier and cooler conditions prior to the eruption. Extensive logging for podocarps in Ohakune-Horopito after AD 1850 resulted in an increase in the abundance of Weinmannia racemosa.