N. T. Moar

Dryland Holocene vegetation history, Central Otago and the Mackenzie Basin, South Island, New Zealand

Abstract Pollen and charcoal analyses are presented from three south‐central South Island Holocene age deposits. A spring bog site in the Idaburn Valley records small‐leaved Olearia scrub and grassland in its immediate vicinity from c. 7100 yr B.P., when peat growth began, to 5000 yr B.P. After that date the valley bottom vegetation became increasingly short and open, and the bog ceased growing, probably as a result of increasingly droughty summers. The adjacent hilly country supported a forest/scrub cover of Podocarpus hallii, Phyllocladus alpinus, Halocarpus bidwillii, and small‐leaved shrubs. A site in the Mackenzie Basin near Lake Pukaki recorded near total dominance by Phyllocladus alpinus scrub from c. 8000 yr B.P. until 5000 yr B.P. after which time Halocarpus bidwillii, Aciphylla, and grassland became increasingly important in response to drought and local fires. At a third site, again in the Mackenzie Basin, Halocarpus bidwillii formed a complete scrub cover at the time of Maori settlement at abo...

Environmental and sea-level changes on Banks Peninsula (Canterbury, New Zealand) through three glaciation–interglaciation cycles

Abstract A greater than 200 ka record of marine transgressions and regressions is recorded from a 75 m core from Banks Peninsula, Canterbury, New Zealand. This record comprises thick suites of muddy sediments attributed to back barrier, lake and lagoonal environments alternating with thin soil and loess complexes. These deposits have been dated using radiocarbon and thermoluminescence (TL) techniques supported by proxy data (diatoms, phytoliths, pollen and sedimentology). The aqueous deposits are attributed to three interglacials and an interstadial (Marine Isotope Stages 1, 5a, 5c, 6, and 7). The loesses and paleosols date to the intervening stadials (Isotope Stages 2, 5d (or 6?) and probably 8). On the basis of transgressive beach facies, back barrier swamps and barrier-blocked lake deposits, a partial sea-level curve including data from Isotope Stage 5 is presented. Our data indicate that Banks Peninsula has been tectonically stable over that period and we provide sea-level points that support the existing isotope curve during Stages 5 and 6. Detailed diatom records are limited to Isotope Stage 1 and the latter part of Stage 5. Diatom histories recorded from these stages are remarkably consistent. Both indicate a progressive floral change from marine types through freshwater colonising species to freshwater planktonic assemblages. These reflect parallel histories of coastal evolution during the two interglacials. In both cases, marine transgression in the early part of the isotope phase was followed by lagoon development implying that a gravel spit extended across the embayment from the west. This was succeeded by lake development when the lagoon was cut off by the juncture of the spit with Banks Peninsula. This lake deepened as the coast rotated into swash alignment and the spit was converted into a gravel barrier. The vegetation history of the site indicates that mixed podocarp broadleaf forests, similar to the pre-European flora of Banks Peninsula, occupied the region during Isotope Stages 1 and 7. This contrasts with the palynological interpretation of a marine record (DSDP Site 594) from off the Canterbury coast which suggested that Isotope Stage 7 was markedly cooler than the Holocene. During glacial periods, forest was eliminated and replaced by a tall shrubland of mixed montane and coastal affinities.

Use of Pollen and Ancient DNA as Conservation Baselines for Offshore Islands in New Zealand

Islands play a key role globally in the conservation of endemic species. Many island reserves have been highly modified since human colonization, and their restoration and management usually occur without knowledge of their prehuman state. However, conservation paleoecology is increasingly being recognized as a tool that can help to inform both restoration and conservation of island reserves by providing prehuman vegetation baselines. Many of New Zealands mammal-free offshore islands are foci for biological diversity conservation and, like many islands in the Polynesian region, were deforested following initial human settlement. Therefore, their current restoration, replanting, and management are guided either by historic vegetation descriptions or the occurrence of species on forested islands. We analyzed pollen and ancient DNA in soil cores from an offshore island in northern New Zealand. The result was a 2000-year record of vegetation change that began >1200 years before human settlement and spanned 550 years of human occupation and 180 years of forest succession since human occupation ceased. Between prehuman and contemporary forests there was nearly a complete species turnover including the extirpation of a dominant conifer and a palm tree. The podocarp-dominated forests were replaced by a native but novel angiosperm-dominated forest. There is no modern analog of the prehuman forests on any northern New Zealand island, and those islands that are forested are dominated by angiosperms which are assumed to be climax forests. The pollen and DNA evidence for conifer- and palm-rich forests in the prehuman era challenge this climax forest assumption. Prehuman vegetation records can thus help to inform future restoration of degraded offshore islands by informing the likely rate and direction of successional change; helping to determine whether natural rates of succession are preferable to more costly replanting programs; and providing past species lists if restoration replanting is desired.

Standardizing names applied to pollen and spores in New Zealand Quaternary palynology

Abstract Pollen analysts often study pollen grains that cannot be easily attributed to a particular taxon. As a consequence, a pollen type may be recorded under various names, leading to uncertainty in their interpretation by others. This limits the usefulness of pollen data for inclusion in databases or meta-analyses. To minimize any such ambiguity, we briefly describe the pollen grains of New Zealand gymnosperms and angiosperms and assign an appropriate name to each. Tree ferns are also included, as they are almost ubiquitous in New Zealand palynomorph records, and are often misidentified and misrepresented. We also provide a review of the occurrence of all taxa in New Zealand pollen records, and of pollination modes, pollen production and dispersal.

Quaternary vegetation and climate changes on Banks Peninsula, South Island, New Zealand

Late Quaternary terrestrial and marine pollen records from the Canterbury Plains and Banks Peninsula suggest that climates during the peak of Marine Isotope Stage 7 (MIS 7) were similar to those prevailing during stage 5e and the Holocene. Podocarp forest (notably Prumnopitys taxifolia-matai) characterises each interglaciation. In contrast, marine records from DSDP 594 cores, off the cast coast of Canterbury, indicate that stage 7 was dominated by montane forest (Libocedrus sp. and Phyllocladus). This suggests temperatures as much as 3 degreesC colder than indicated by the Banks Peninsula assemblage. Age control from both sites appears to be robust. Some of the differences may be related to the taphonomy of the pollen at both sites. DSDP 594 may reflect a more southerly catchment of fluvially and aeolian-derived pollen than does the Banks Peninsula site. Banks Peninsula was alternately separated from, and joined to, the mainland as Quaternary sea levels fell and rose. Assuming modem ocean current patterns, during interglacials the south-north Southland Current would have swept through the seaway separating the island from the mainland, diverting the flow of rivers embouching on the Canterbury coast, and moving sediments and fluvially transported pollen northwards. Little of this material would have reached DSDP 594, nor, if wind patterns were similar to those of today, would wind-borne pollen from Banks Peninsula have reached the site. It is probable that vegetation on the Peninsula was consistently distinct from that recorded at DSDP 594, which has a more southerly derivation. In contrast to the high mountain areas of the South Island, the low levels of grass pollen in the available record suggest that the Peninsula retained a woody vegetation over much of its area during glacial periods. This was favoured by the physiography of the area, with a variety of micro-climates, and by the extensive areas available for colonisation at times of low sea level. The podocarp forest of MIS 7 was replaced by an open shrubby vegetation in which Leptospermum and Kunzea (Leptospermum-type pollen) was locally dominant, and in which Plagianthus, Phyllocladus, Coprosma and Myrsine were prominent. Charcoal is associated with this change. Most of the recorded taxa, with the exception of Phyllocladus, are present on the Peninsula today. A gap in the pollen record coincides with the Last Interglacial and Last Glaciation, but a return of forest vegetation is documented in the later Holocene. The reconstructions do not exclude the possibility of a cooler stage 7. They do highlight the importance of excluding local/regional non-climatic effects before interpreting climate change from data sets, and reinforce the necessity of testing marine records against compatible terrestrial ones

A key to the pollen of New Zealand Cyperaceae

Abstract The pollen of New Zealand Cyperaceae have not been previously identified below family level. However, a recent shift towards studying more ecological detail with greater temporal resolution in palynological research has now led to a demand for greater precision in pollen identification. In this paper we describe the pollen characteristics, mainly grain shape and aperture type, of representatives of each New Zealand Cyperaceae genus. Twelve distinct groups are defined, and a key is provided to assist with their identification, usually either to a genus or to a group of genera described as a particular type.

New palaeontological data from the excavation of the Late Glacial Glencrieff miring bone deposit, North Canterbury, South Island, New Zealand

The avifauna from the Glencrieff swamp deposit in North Canterbury, South Island, New Zealand, is described. Radiocarbon ages of moa bones bracket miring at the site to between 10,000 and 12,000 (uncalibrated) years BP. Heavy-footed moa (Pachyornis elephantopus) and eastern moa (Emeus crassus) dominated the moa assemblage at the site, while South Island giant moa (Dinornis robustus) and stout-legged moa (Euryapteryx curtus, formerly E. gravis (in part)) were rare. The total assemblage from the site consists of at least 1896 bones from 18 species of birds, of which nine are extinct and a further three locally extinct. In addition, we report on the discovery of the oldest known moa gizzard contents, the palynology of the Glencrieff deposit and comment on significant recent changes in site preservation conditions that are threatening the continued preservation of this significant fossil deposit.

Environments during the Kaihinu Interglacial and Otira Glaciation, coastal north Westland, New Zealand

Abstract Shoreline gravel of a 47 m raised beach 15 km north of Greymouth, north‐west South Island, is overlain by 6 m of lagoonal deposits, beginning with fine organic silts from which pollen records the replacement of an early podocarp‐hardwood forest by Nothofagus‐podocarp and then by Nothofagus forest. Plant macro‐remains, including Dacrydium cupressinum (rimu), Nothofagus menziesii (silver beech), N. truncata (red beech), and N. solandri var. cliffortioides (mountain beech), clarify the nature of these forests. Radiocarbon dates >50 000 14C yr BP and comparison with other north Westland sequences lead to correlation with the early Kaihinu (Last) Interglacial, and assignment to MIS5e and 5d. Locally overlying are 12 m of interbedded slope deposits and alluvial gravel, together with seven organic silt layers (Bed A down to Bed G). Leaves of Nothofagus menziesii were recovered from Bed G and N. solandri var. cliffortioides from higher layers. Bed B shows a significant Poaceae maximum. Radiocarbon dates from Beds G and E are 42700 ± 1300 and 22280 ± 150 14C yr BP, respectively. The sequence represents much of the Otira (Last) Glaciation, MIS3 and MIS2. The persistence of trees and shrubs at this coastal site is consistent with the inference of closed canopy forest from a site near Westport, but contrasts with the dominance of Poaceae and Cyperaceae at previously studied inland Otira Glaciation sites.

A mid Otira Glaciation palaeosol and flora from the Castle Hill Basin, Canterbury, New Zealand

Abstract A section exposed at the Broken River road cutting in Castle Hill Basin revealed a palaeosol resting on reddish, rusty gravel and beneath 30 m of fresh-looking, grey, glacio-fluvial outwash gravel deposited by a meltwater stream during the Black-water advances of the Waimakariri Glacier. A radiocarbon date >37 000 ± 200 yr B.P. (NZ 7518) was obtained for the palaeosol. Pollen spectra from it are dominated by a herbaceous plant assemblage indicating cold climatic conditions. Redeposited pollen from adjacent Tertiary rocks is also present. The soil appears to have been formed in a marshy habitat soon after the onset of the Blackwater 1 glacial episode (the first cold phase of the middle part of the Otira Glaciation).

Wood anatomy of the dicotyledons indigenous to New Zealand 26. Rutaceae

Abstract Wood anatomy of Melicope ternata, M. simplex, and Phebalium nudum is described. In M. simplex and M. ternata vessels have no helical thickenings, most perforation plates are simple but some are scalariform or reticulate, grooves connect pit apertures, and vessel to ray pits are sometimes unilaterally compound. Disjunctive ray and axial parenchyma cells are present. Melicope simplex is distinguished from M. ternata in having narrower rays, more disjunctive ray cells, and narrower boundary bands of axial parenchyma. The vessel elements of P. nudum have helical thickenings and simple perforation plates, and lack unilaterally compound pits. Disjunctive axial parenchyma cells are absent and disjunctive ray cells are rare. Boundary axial parenchyma and rays are usually only 1-2 cells wide. Vasicentric tracheids are common in P. nudum but rare in M. simplex and M. ternata. Silica bodies occur in the parenchyma cells of all three species.