Affiliation:
1. School of Geography, Environment and Earth Sciences Victoria University of Wellington Wellington New Zealand
2. Antarctic Research Centre Victoria University of Wellington Wellington New Zealand
3. New Mexico Bureau of Geology and Mineral Resources New Mexico Institute of Mining and Technology Socorro New Mexico USA
4. School of Environment The University of Auckland Auckland New Zealand
Abstract
ABSTRACTThe ~25.5‐ka Ōruanui supereruption (Taupō volcano, New Zealand) erupted >1100 km3 of pyroclastic material during the Last Glacial Maximum. The impacts of this event on climate and the New Zealand environment remain unresolved, particularly on ecological timescales. Using sediment cores from Onepoto maar palaeolake, Auckland (~240 km upwind from source), we have analysed pollen assemblages at contiguous 1‐mm intervals, around an intact 3‐cm layer of the Kawakawa‐Ōruanui Tephra to resolve and assess post‐eruption vegetation impacts and landscape recovery. Sediments immediately above the tephra record a decline in the relative abundance of the dominant canopy species of Fuscospora, and concurrent increase in the abundances of grasses, herbs, ferns and shrubs. These changes reflect a brief (<10 years) part‐defoliation of canopy trees, permitting more light to penetrate and to encourage sub‐canopy vegetation growth. A short‐lived volcanogenic cooling inferred from Antarctic ice core records may have contributed to the changes but cannot be separated from the immediate and direct ecological impacts of ashfall on vegetation following the eruption. Our results, here applied to the world's most recent supereruption, more generally demonstrate the value of millimetre‐scale stratigraphic pollen analysis from non‐varved lacustrine sediments as a tool for assessing past eruptive impacts on sub‐decadal timescales.
Subject
Paleontology,Earth and Planetary Sciences (miscellaneous),Arts and Humanities (miscellaneous)