Composition and structure of forest overwhelmed at Pureora, central North Island, New Zealand, during the Taupo eruption (c. AD 130)

Abstract

The composition and structure of forest at Pureora, overthrown and buried by pumiceous tephra during the c. AD 130 Taupo eruption, are deduced from identification of plant macrofossils. A tall, dense podocarp forest was dominated by rimu (Dacrydium cupressinum) and tanekaha (Phyllocladus trichomanoides), with occasional matai (Prumnopitys taxifolia), miro (Prumnopitys ferruginea), kahikatea (Dacrycarpus dacrydioides) and totara (Podocarpus totara). Understorey plants included toro (Myrsine salicina), horopito (Pseudowintera colorata), Neomyrtus pedunculata, Metrosideros diffusa, crown fern (Blechnum discolor) and Leptopteris superba. Poorly drained sites were dominated by kahikatea, rimu, tanekaha, Astelia grandis, Gahnia xanthocarpa and kiekie (Freycinetia baueriana ssp. banksil) with rare bog pine (Halocarpus bidwillil) and kaikawaka (Libocedrus bidwillil)' The classification and ordination techniques applied indicated that the forest was basically of one type with minor variations reflecting drainage conditions and topography. Comparison with present-day forest revealed some major differences. Matai and rimu dominate the tall podocarp forest of adjacent Pikiariki Ecological Area, and tawa (Beifschmiedia tawa), mahoe (Melicytus ramijlorus ssp. ramijlorus), kamahi (Weinmannia racemosa) and Asplenium bulbiferum s.s. are common in the understorey or ground cover but were not recorded in the buried forest. Kiekie, Gahnia xanthocarpa and kaikawaka, on the other hand, are absent from present-day forest in the Pureora district. These species were probably casualties of the volcanic devastation, unable to return because of one or a combination of factors, including improved soil aeration, drainage and fertility, and possibly a deterioration in climate.

Macrofossils and pollen representing forests of the pre‐Taupo volcanic eruption (c. 1850 yr BP) era at Pureora and Benneydale, central North Island, New Zealand

“…The buried forest sites at Pureora (37 ha) and Benneydale ( 1.9 ha) are 20 km apart in the west Taupo region, central North Island, as described in Clarkson et al (1988Clarkson et al ( , 1992. At both sites, prone trees and intact litter layers, preserved beneath a layer of Taupo Ignimbrite up to 1 m thick, were exposed along ditches dug to drain post-Taupo eruption wetlands (Fig.…”

“…Both sites are now formally protected: Pureora buried forest is in Pureora Forest Park, which is administered by the Department of Conservation (cf. Clarkson et al 1988); Benneydale buried forest is under an Open Space Covenant administered by the Queen Elizabeth II National Trust. All except one of the peat and tephra samples for pollen analysis, radiocarbon dating, and tephra composition were collected in Spring, 1992.…”

“…The data are detailed in Clarkson et al (1988Clarkson et al ( , 1992. Percentage litter cover for each species was defined as: " .…”

“…The first part of the study investigated forest structure and composition at Pureora and Benneydale from the macrofossils (Clarkson et al 1988(Clarkson et al 1992. This second part Fig.…”

Taxonomy and Ecology of Sponge‐Associate Marionina spp. (Clitellata: Enchytraeidae) from the Horomatangi Geothermal System of Lake Taupo, New Zealand

“…That eruption is acknowledged as the world's largest volcanic eruption in historical times, with its effects in the sky recorded in Roman and Chinese literature (WILSON et al, 1980). Forests in the surroundings were buried in meters of volcanic fallout (e.g., CLARKSON et al, 1988) and it is estimated that if the same eruption occurred today, ashfall and other debris would cause chaos from Hamilton to Palmerston North. Such a devastating event and the subsequent changes in soils and climates must have heavily re-shaped the landscape of the central North Island, and no doubt all inland waters in that area became azoic.…”