Ascarina Lucida Research Articles

Reconnaissance sediment and microfossil analyses of a laminated short piston core from Lake Tekapo, South Island, New Zealand

A 2.2 m piston core from the main basin of Lake Tekapo comprises millimetre‐centimetre‐scale alternations of light and dark laminae. Two much thicker layers occur near the base of the core and are interpreted as major slump deposits. Light laminae are predominantly fine silts with low microfossil concentrations. Dark laminae have higher clay, mica, and microfossil content and higher planktic/benthic diatom ratios. These findings are consistent with light laminae being deposited during times of high river flow and high sediment input, the thickness and number forming a proxy for paleoclimate (rainfall, water inflow, and erosion rates), and the dark laminae being deposited by settling out of the water column during periods of low inflow. The distribution of pollen from plants introduced to New Zealand by Europeans, and the inconsistency of dominant pollen types between samples, suggests that the entire sequence is only c. 100 yr old and that couplets of light and dark laminae form more frequently than annually. With appropriate processing, diatoms, spores, and pollen are present in great enough numbers in the dark laminae to be used for paleoclimate reconstruction. Diatoms are predominantly planktic lacustrine forms with some benthic forms sourced from the lake margins. Pollen and spores are derived from local grasslands, montane forest, fell fields, and tussock lands, and from West Coast lowland forest. Palynomorphs are carried over the central Southern Alps by prevailing northwesterly winds, and are deposited in the lake. The presence of fresh‐looking Casuarina and possibly Banksia and Eucalyptus pollen shows that it is likely that some pollen came from Australia. It is believed that the presence and abundance of West Coast derived pollen, particularly Dacrydium cupressinum, and to a lesser extent Ascarina lucida, Nothofagus, and Podocarpus/Prumnopitys species, could be used as a proxy for the intensity and persistence of northwesterly winds.

A Late Quaternary pollen record from Lake Tangonge, far northern New Zealand

Vegetation and climate changes during the Last Glacial through to the late Holocene are identified by pollen analysis of a core from Lake Tangonge in far northern New Zealand. During the earliest part of the record (> 50 ka), regional vegetation was dominated by podocarp-hardwood forest. The most important tall podocarp trees were Dacrydium cupressinum and Dacrycarpus dacrydioides. Knightia and Metrosideros sp. were common, and angiosperm elements dominated lowland/coastal forests. The cool, moist climates, of what may be equated to Marine Isotope Stage (MIS) 4, were followed by a much wetter and slightly warmer period during MIS 3b (59–43 ka) when Ascarina became more abundant along with Dacrycarpus dacrydioides, Metrosideros sp., Quintinia and Syzygium maire. From ca. 43 to 24 ka (MIS 3a) Agathis australis-dominated, mixed, conifer–hardwood forest expanded and hardy podocarps, Podocarpus and Prumnopitys taxifolia, became more abundant. Ascarina lucida was scarce. Climates characterised by drier summers and cooler winters became increasingly colder, drier and windier, particularly from ca. 30 ka. Replacement of Agathis australis–podocarp–hardwood forest with Fuscospora–podocarp–hardwood forest followed rapidly, and by the Last Glacial Maximum Northland forests as far north as ca. 35°S were dominated by Fuscospora. Bog vegetation burned frequently. Regional temperatures may have been depressed by as much as 3–3.5 °C below those of today, and rainfall was probably reduced by about two-thirds. Warm, moist elements expanded in the late glacial as the glacial-type flora became increasingly restricted. Changes in forest composition progressed even more rapidly from the onset of the Holocene. Across the far northern region, Fuscospora-dominated podocarp–hardwood forest was rapidly replaced by Agathis australis–podocarp–hardwood forest. Fuscospora declined sharply and Dacrydium cupressinum dominated regional forests. Hardy podocarps became less common than previously, and Ascarina reached its greatest abundance between ca. 10 and 7.6 ka. The early Holocene climate was probably the warmest and most equable for the past 100 ka and temperatures in the Kaitaia region may have been 1–2 °C warmer than present. The mid-to-late Holocene (5–2 ka) is characterised by the decline of Ascarina, and the increased abundance of Manoao colensoi, Podocarpus and Prumnopitys taxifolia. Climates were probably slightly cooler and drier during this time as a more seasonal, dry summer/wet, cool winter regime prevailed. Increased cyclonic activity is suggested during this time.

The seed ecology of Ascarina lucida: A rare New Zealand tree adapted to disturbance

Ascarina lucida is rare in the North Island of New Zealand, occurring as small scattered populations. The seed ecology of this species was investigated by laboratory germination of fresh seed, and germination of samples from soil seed banks of two North Island populations. Seed collected from a submontane population had higher germinability (76%) than seed collected from a lowland population (32%). Seed collected from an isolated lowland garden tree had high germinability (82%). A. lucida seeds were abundant in both the surface and basal soil layers, and it was predicted that the species maintains a persistent seed bank for up to c. 8 years. A. lucida was the dominant component of the seed bank at the submontane site. The germination pattern of A. lucida was compared with other woody species in the seed bank and found to have similarities with species that often colonise disturbed sites. The maintenance of a persistent seed bank, coupled with the long period of time over which fresh seed germinates, gives this species flexibility in the timing of germination. Overall, the results indicate that the species is adapted to disturbed environments.

Late Quaternary pollen records of vegetation and climate change from Kaitaia Bog, far northern New Zealand

A vegetational history and palaeoclimatic changes are established for the last 25,000 yr by pollen analysis of two peat cores from Kaitaia Bog, far northern New Zealand. Twelve AMS radiocarbon dates provide a chronology covering the Last Glacial Maximum to the late Holocene, ca. 2500 yr ago. Prior to 22,000 yr B.P. a tall, complex, conifer-beech-hardwood forest dominated by podocarp trees covered the region. The most abundant of these was Dacrydium cupressinum. Nothofagus ( N. cf. truncata) was also an important element. Other common emergent trees included Podocarpus, Prumnopitys ferruginea, P. taxifolia, Dacrycarpus dacrydioides, Libocedrus and Metrosideros. From 22,000 to ca. 14,000 yr B.P. regional forest was dominated by Nothofagus cf. truncata, and warm, moist elements such as Ascarina lucida and Agathis australis were scarce. This Last Glacial Maximum forest cover contrasts with the open grass and shrub communities which dominated landscapes south of Auckland. Cool climate species such as Nothofagus cf. truncata began to decline towards the end of the Lateglacial, and from ca. 11,300 yr B.P. Ascarina lucida started to increase rapidly. Replacement of conifer-beech-hardwood forest with a conifer-hardwood association proceeded rapidly in the Postglacial as Nothofagus cf. truncata retracted sharply and Dacrydium cupressinum increased in abundance. The regional expansion of Agathis australis followed rapidly. Regional forest in the mid- to late Holocene consisted of a conifer-hardwood association dominated by Dacrydium cupressinum, Podocarpus, Phyllocladus and Agathis australis. A mid-Holocene decline for Ascarina lucida and coincident increased abundance of Prumnopitys taxifolia suggest somewhat cooler conditions prevailed from this time. Nothofagus cf. truncata, though still present, assumed only a minor role as more favourable conditions allowed other species a competitive advantage.

A late Holocene pollen record of deforestation and environmental change from the Lake Tauanui catchment, Northland, New Zealand

Late Holocene pollen and sediment records from the Lake Tauanui catchment, northern New Zealand, indicate that the lake formed about 5500 years ago following a series of volcanic events in the Tauanui Volcanic Centre. These volcanic events initiated a volcanosere resulting in a mixed conifer-hardwood forest. Dacrydium cupressinum was the dominant tree. Agathis australis was always present. Changes similar to those registered in other Northland pollen diagrams are apparent. At ca 4000 yr B.P., when the climate became cooler and drier than before, a fire occurred in the catchment area causing erosion of the surrounding slopes and some destruction of forest. Fluctuations in abundance of many forest species, including Ascarina lucida, A. australis and D. cupressinum, from ca 3500 yr B.P. indicate repeated disturbance, increasingly so after 1600 yr B.P. Summer droughts and increased frequency of cyclonic winds are suggested as the cause. Major anthropogenic deforestation events defined by palynology occurred across many parts of the New Zealand landscape at ca 700 yr B.P. At Lake Tauanui anthropogenic forest disturbance, radiocarbon dated to ca 1000 yr B.P., is indicated by significant decline in all tree and shrub elements with concomitant increase in pteridophytes, especially Pteridium esculentum. Charcoal concentration increases steadily from the onset of disturbance, and in the final phase after the arrival of Europeans, major clearance of vegetation is indicated. Herbs increase markedly in this period, in diversity and abundance.

Holocene vegetation, climate and history of a raised bog complex, northern New Zealand based on palynology, plant macrofossils and tephrochronology

A Holocene history of vegetation, climate, and ombrogenous mire development is presented from pollen and plant macrofossil analyses of sediments at Kopouatai Bog, a large, raised, restiad bog in northern New Zealand. Tephra layers of established ages, supplemented by numerous radiocarbon dates, provide a secure chronology. The earliest peats, overlying last glacial sediments, and dated at c. 11700 radiocarbon years BP, with extensive accumulation after c. 10360 BP, are dominated by pollen of warm temperate podocarp-angiosperm forest, indicating a moist, mild early-Holocene climate. The bog began as a series of small soligenous mires within lowland podocarp-dominated swamp forest but was mostly oligotrophic by c. 8500 BP. Peat accumulation rates have varied spatially and temporally, averaging 0.9 mm yr-1 in central and southern areas. The deposition of deltaic muds in the northern part of the bog accompanied a marine transgression c. 6500-5000 BP, while elsewhere an associated groundwater table rise resulted in a temporary return to mesotrophic conditions. As the marine influence subsequently receded, the northern areas remained subject to regular flooding, but underwent rapid peat growth at a mean rate of 1.7 mm yr-1, while oligotrophic conditions returned to other parts of the bog. Regional vegetation developments indicate a change, c. 6000 BP, to drier, frostier conditions during the late Holocene. Ascarina lucida and Agathis australis may be used as regional pollen- stratigraphic markers for the early Holocene and late Holocene, respectively. The loss of tall trees and expansion of subcanopy species and seral vegetation in forests near Kopouatai Bog, just before the deposition of Kaharoa Tephra (c. 700 BP), are likely evidence for human activity dating from at least this time.

Palynological and Sedimentological Evidence for a Radiocarbon Chronology of Environmental Change and Polynesian Deforestation from Lake Taumatawhana, Northland, New Zealand

We present pollen diagrams and sedimentological analyses from a lake site within an extensive dune system on the Aupouri Peninsula, Northland. Five thousand years ago, a regional Agathis australis–podocarp-broadleaf forest dominated the vegetation, which manifested an increasing preponderance of conifer species. Climate was cooler and drier than at present. From ca. 3400 bp, warmth-loving species such as A. australis and drought-intolerant species, Dacrydium cupressinum and Ascarina lucida, became common, implying a warm and moist climate. The pollen record also suggests a windier climate. The most significant event in the record, however, occurred after ca. 900 bp (800 cal bp) when anthropogenic deforestation commenced. A dramatic decline in forest taxa followed, accompanied by the establishment of a Pteridium–esculentum-dominated community. Fire almost certainly caused this, evidenced by a dramatic increase of charcoal. Sedimentological evidence for this site indicates a relatively stable environment before humans arrived and an increasingly unstable environment with frequent erosional events after human contact.

The late pleistocene and holocene vegetation history of Taranaki, North Island, New Zealand

Abstract Pollen diagrams are presented from four lowland Taranaki sites which collectively span the last 13 000 years. Atc. 13000 years ago, lowland Taranaki was occupied by an open grassland in which shrubland was restricted and forest scarce. Beginning c. 12 500 years ago, there was a rapid transition, essentially complete by 11 000 years ago, to tall complex conifer/broad-leaved forest in which Prumnopitys taxifolia was the most abundant tall tree. By 9500 years ago, the last of the cool temperate forest elements (most notably Nothofagus menziesii and Libocedrus bidwillii) had been eliminated from the forest, and Dacrydium cupressinum had supplanted Prumnopitys taxifolia as the most abundant tall podocarp tree. In coastal regions, Ascarina lucida and Dodonaea viscosa were abundant. From 5000 years ago, Ascarina lucida and Dodonaea became much less common, and Ascarina lucida is now nearly extinct in the Taranaki region. Knightia excels a and Lagarostrobos colensoi spread during the late Holocene. The e...

New Zealand thesis in Earth sciences

This study attempts to reconstruct the vegetational and climatic history of the last 300 000 years for the Taranaki-Wanganui district, North Island, New Lignites in the cover beds of a wellpreserved sequence of marine terraces in South Wanganui Basin provide excellent material for pollen analysis from sequences that are chronologically constrained by the ages of the marine terraces and by the loessand tephrostratigraphy of their cover beds. Anthropogenic influences in New Zealand affect only the last c. 1000 years. Modern pollen samples from a variety of vegetation types from central-western North Island, together with previous modern pollen studies, indicate the palynological representation of taxa and allow the characterisation of the major vegetation types, although these data provide only a limited picture of the source vegetation. This information is used for helping to interpret the fossil pollen spectra. Two sites from the Waverley district, near Wanganui, which together cover the mid and late Holocene, provide an analogue of vegetation assemblages and their sequence of development in the area, for use in interpreting the Pleistocene pollen sequences. The vegetation history from these sites conforms to the known Holocene pattern from sites elsewhere. Polynesian deforestation at Lake Waiau Swamp is estimated to have occurred some time between 685 CAL B.P. and 210 years ago. Five sites from the Pleistocene marine terrace cover beds are pollen analysed in detail. The pollen assemblage zones are correlated with the established deep-sea oxygen isotope record. Combined with previous pollen studies from the terrace cover beds, the results provide a relatively continuous, detailed vegetation history dating from c. 400 ka ago to the present, for the fIrst time in New This record is closely linked to the marine terrace, loess-, and tephrostratigraphy of this region. Because the record is mostly from sequential rather than coeval sites, further work is required to corroborate certain details. The vegetation on the lowlands of Taranaki-Wanganui alternated from grass-shrubland communities during glacial periods, to podocarp-hardwood forest, dominated in the pollen assemblages by Dacrydium cupressinum, during the interglacial times. No particular period is uniquely characterised by its pollen assemblages. In interglacial pollen assemblages, generally some of the hardwood forest elements are severely underrepresented (e.g., Beilschmiedia tawa). The warmest, wettest, and mildest (with rare frosts and droughts) climates during interglacials are suggested by pollen assemblages matching those of the early to mid Holocene, with common Ascarina lucida and Dodonaea viscosa pollen in nearcoastal sites. Interstadial and stadial pollen assemblages are more diffIcult to characterise. In general, interstadial assemblages seem to be dominated by Prumnopitys taxifolia pollen, and· stadial assemblages seem to be dominated by Nothofagus fusca type or Libocedrus pollen, together with common shrub and grasS pollen. The vegetation for Some of the climatic stages, such as the Last and Penultimate Interglacials sensu stricto, are clearly demonstrated for the first time in New N. fusca type, N. menziesii, Libocedrus, Halocarpus, Phyllocladus, Empodisma minus, and Gleichenia are some taxa for which geographic range expansion. can be demonstrated when climates were cooler than present However, the vegetation history of the area generally agrees with the hypothesis that the flora of the Taranaki-W~ganui district has remained essentially the same through the Q\1aternary, although a few records of taxa well outside their present ranges require special explanation. Glacial period pollenrecords show that, while forest was probably largely excluded from the lowlands, it remained in the region during the coldest climatic periods and probably occupied sheltered areas. Broadly synchronous records from separate sites suggest that regional vegetational differences existed, probably due to local site and climate differences, analogous to the present pattern. Occasional natural fIres appear to have occurred throughout the periods studied, but there is no evidence that deforestation due to severe fIres occurred during the late Pleistocene. Palynology and radiocarbon dating of the Ohawe Beach Site, near Hawera, demonstrate that the marine terraces in this region have previously been mapped incorrectly, but in general the marine terrace mapping and chronology of B. J. Pillans (1983:. Upper Quaternary marine terrace chronology and deformation, south Taranaki, New Zealand. Geology 11: 292-297;) is upheld. Radiocarbon dating of separate organic fractions from degraded fossil wood samples at Ohawe Beach show that chemical contamination by young radiocarbon had occurred· and that the real age is beyond the radiocarbon range. This serves as· a warning against simple interpretation of radiOCarbon ages on wood from cover beds in the area. Pollen analyses also suggest that the Fordell Ash is younger than the Mt Curl Tephra, as opposed to previous interpretations . The extinct palynomorphs, Acacia· type andPeromonolites problematicus Couper, are identifIed from the cover beQ sediments, and their time ranges in New Zealand extended until c .. 11 0 ka ago and 90 ka ago, respectively. The implications of these fIndings are discussed. .

Mid and late Holocene pollen diagrams and Polynesian deforestation, Wanganui district, New Zealand

Abstract Two sites near Waverley, western North Island, provide a mid to late Holocene vegetational, climatic, and fire history for the area. A mid Holocene flora at Waverley Beach includes a local fossil Podocarpus totora forest preserved as in situ stumps exposed in Hauriri Terrace cover beds. Fossil pollen suggests the presence of surrounding podocarp-hardwood forest dominated by Beilschmiedia tawa(?) and Dacrydiwn cupressinum but with common Ascarina lucida and Dodonaea viscosa in the understorey, suggesting a maritime, moist, warm-temperate climate was present. At Waverley Beach, the local, dense forest phase of Podocarpus totara appears to have been eliminated by water table elevation following the post-glacial rise in sea level up to 6500 BP. The decline in abundance of Ascarina and Dodonaea pollen from the mid to late Holocene is suggestive of a milder climate during that period. Around Lake Waiau swamp, pre-clearance podocarp-hardwood forest was probably dominated by B. tawa(?), D. cupressinum, P...

Modern pollen rain, central-western North Island, New Zealand

Abstract Moss polsters were analysed for their modern pollen rain from a range of vegetation associations in central-western North Island. The reconstruction of source vegetation and the representation of various taxa in the pollen rain is discussed. The pollen rain presented a rather distorted view of source vegetation, however, the presence of either low pollen percentages of key local taxa with poorly dispersed pollen, or very high pollen percentages for taxa growing locally with wide or poor pollen dispersal capabilities, allowed a general determination of the source vegetation types. Prolific pollen producers, particularly Nothofagus fusca-type, were found to mask out the pollen of other taxa which dominated vegetation associations growing near to Nothofagus forest. Nothofagus fusca-type pollen were below five percent of total in areas of Taranaki where no Nothofagus is present. Under- and severely under-represented taxa were numerous. Ascarina lucida was probably more common in the recent past in Ta...

The effect of recent volcanic events and climatic changes on the vegetation of Mt Egmont (Mt Taranaki), New Zealand

Abstract Pollen diagrams are presented from two mires on the flanks of the recently active andesite stratovolcano of Mt Egmont. The diagrams span the last 3500 years, and record both climatic and volcanic induced changes to the broadleaf-podocarp forests, scrub, and shrublands which clothe the slopes of Mt Egmont and the adjacent Pouakai Range to the north. Libocedrus bidwillii and Weinmannia racemosa are common trees in the upper montane forest. Both have fluctuated in abundance over the past 3500 years, with Libocedrus being most abundant between c. 3000 and 2500 years ago, and c. 1400 and 450 years ago, and Weinmannia more common in the intervening periods. Libocedrus dominance is associated with evidence for slope instability, and it is suggested that it reflects cooler, stormier conditions. There is little evidence for climatically induced vegetation change in the lower montane forests, except that Ascarina lucida became rare after c. 1400 years ago, which many also indicate cooler conditions. The la...

Vegetation history and environmental significance of pre-peat and surficial peat deposits at Ohinewai, Lower Waikato lowland

Abstract The Ohinewai peatlands occupy 15 km2 near Lake Waikare, south Auckland. The peats average 6–9 m in depth, and overlie a grey-green lacustrine mud (3–11 m thick). The lacustrine mud was deposited in a proto-Lake Waikare between 20,000 and 7,000 yr bp, and pollen analysis shows that open shrubland-grassland vegetation was dominant for at least a portion of this time. The basal peat ranges in age from 7,000–6,000 yr bp. The peat formed in an oligotrophic raised bog during the drainage and contraction of the proto-Lake Waikare, a process which may have been caused by a drop in sea level. Pollen analysis of the peat shows that conifer-hardwood forest, similar to that of the present, was dominant throughout. Ascarina lucida and Dacrydium colensoi, trees which are extinct, or nearly so, in the region today, were present until at least 2,000 yr BP. There was little change in the forest between 7,000 and 2,000 yr bp, except for a marked increase in Agathis austrahs at around 3,000 yr BP, which may indicat...

Long-distance pollen transport over the southern Tasman Sea: evidence from Macquarie Island

Abstract Numerous exotic pollen and spore types occur in Holocene lake deposits on Macquarie Island. Most are con~idered to be derived from sources in the south-east Australian region. Myrtaceae pollen, which probably includes both Eucalyptus and Metrosideros, accounts for over 40% of the total exotic counts for 2 cores. Podocarpaceae, Phyllocladus, Casuarina, and Pomaderris are also present in significant proportions. Single records for Dacrydium cupressinum and Ascarina lucida, and the absence of Nothofagus “fusca” suggest that New Zealand pollen sources are relatively poorly represented. This find emphasises the need for caution when assessing the nature of the exotic pollen rain at sites on mainland New Zealand and surrounding islands.

New and significant plant distribution records from northern New Zealand

Abstract Comments are made on the distribution north of about latitude 38° of 31 rare or locally indigenous taxa. The rediscovery of Asplenium hookerianum, Corybas unguiculatus, Doodia aspera, and Pseudopanax gilliesii in North Auckland is documented. Significant northward extensions of geographic range are made for Asplenium flabellifolium, Ascarina lucida, Dracophyllum pyramidale, and Phymatosorus novae-zelandiae. The first mainland records are published for the hybrid Asplenium oblongifolium × A. obtusatum subsp. northlandicum.

Holocene pollen diagrams from Pauatahanui Inlet, Porirua, New Zealand

Abstract Pollen analysis of two radiocarbon-dated sequences in Pauatahanui Basin, on the west coast of southern North Island, shows that for the last 8000 years or more a Dacrydium cupressinum-dominant broadleaf-podocarp forest existed in the area. During this period D. cupressinum has slowly declined in favour of Podocarpus, Noihofagus “fusca” beech, and Metrosideros. Ascarina lucida also slowly declined. This suggests a slow deterioration of the climate, particularly from about 5000 years ago, probably due to increased frostiness and summer droughts. Knightia excelsa pollen is recorded only in the top half of both sequences. Its arrival is dated at approximately 3400 years b.p. The top of the sequences, where pollen and spores of Pteridium aquilinum, Gramineae, Compositae (Liguliflorae), Pinus, and Cupressus are abundant, clearly show the arrival of Polynesian and European man into the area. The broadleaf-podocarp forest at Pauatahanui was contemporary with a beech forest (at Wallace-ville) and beech-po...

The flowers ofAscarina lucidaHook. f. (Chloranthaceae)

Abstract Ascarina lucida is not dioecious as has been assumed but exhibits a peculiar type of monoecism. Biparous sessile cymes composed of simple unisexual flowers are, with very few exceptions, of two kinds. One stamen constitutes a male flower and commonly each is accompanied by two female flowers which mature distinctly later; on other compound inflorescences, a stamen and a single accompanying female flower mature almost simultaneously, so that the much reduced cyme resembles a bisexual flower. Similar cymes occur on plants from the Kermadec Islands (A. lucida var. lanceolata (Hook, f.) Allan).

TheAscarinadecline and post-glacial climatic change in New Zealand

Abstract Ascarina lucida was abundant in the west of both the North and the South Island between c. 10 000 and 5 000 yr b.p., but since then it has been severely and progressively reduced in quantity. It is now common only on the west coast of the South Island, and elsewhere occurs in scattered localities in the northern South Island and the North Island. Because Ascarina is frost and drought sensitive we suggest that an increased incidence of theso two factors is responsible for its elimination from previously suitable areas.