198 results for Lowe, David J.

  • Assessing drivers of plantation forest productivity on eroded and non-eroded soils in hilly land, eastern North Island, New Zealand

    Heaphy, Marie; Lowe, David J.; Palmer, David John; Jones, Hayden S.; Gielen, Gerty J. H. P.; Oliver, Graeme R.; Pearce, Stephen H. (2014-07-02)

    Journal article
    University of Waikato

    Methods: The impact of soil erosion by mass movement on forest productivity was investigated in a paired plot trial in a planted forest in a mainly hilly to steepland catchment (Pakuratahi) near Napier, eastern North Island, New Zealand. Tree growth and form were measured and soil properties analysed to compare productivity and productivity drivers in adjacent non-eroded and eroded plots. Background: The effect of soil erosion on New Zealand production forestry is not well known and there has been no research prior to our study into the relationship between soil nutrient status and planted forests growing in eroded soils in steeplands. Results: Regression analysis showed that the decreased soil total nitrogen, total carbon, total phosphorus, and soil organic matter content in eroded plots had a negative impact on tree volume, resulting in a 10% decrease in measured tree volume. Based on an assessment of log quality, trees in the eroded plots were forecast to produce 16% less volume from high-quality pruned logs (with associated reduction in revenue of around $4000 per hectare), than trees in non-eroded plots. The total recoverable volume (TRV), estimated (for a 25-year rotation) from the measured Pinus radiata D. Don trees growing on the eroded sites, was valued at $68,500, about 9% less than the estimated TRV from trees measured on non-eroded plots ($76,000). Tree form and mean tree height in eroded and non-eroded plots were not significantly different. Conclusions: Soil erosion impacts production in planted forests. Afforestation of erodible land provides a valuable ecosystem service through land and soil stabilisation but this service is currently not reflected in the market prices for timber in New Zealand. Maintaining the productive capacity of erodible soils through practices such as fertilisation or continuous-cover forestry can add further costs to production forestry. To ensure that sustainable forest practices are carried out to protect the productivity of soils, financial incentives may be justified.

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  • INTREPID Tephra-II: - 1307F

    Lowe, David J. (2013)

    Journal article
    University of Waikato

    The INTREPID Tephra project, “Enhancing tephrochronology as a global research tool through improved fingerprinting and correlation techniques and uncertainty modelling”, was an overarching project of the international community of tephrochronologists of the International Focus Group on Tephrochronology and Volcanism (INTAV), which in turn lies under the auspices of INQUA’s Stratigraphy and Chronology Commission (SACCOM). INTREPID’s main aim has been to advance our understanding and efficacy in fingerprinting, correlating, and dating techniques, and to evaluate and quantify uncertainty in tephrochronology, and thus enhance our ability to provide the best possible linking, dating and synchronising tool for a wide range of Quaternary research projects around the world. A second aim has been to re-build the global capability of tephrochronology for future research endeavours through mentoring and encouragement of emerging researchers in the discipline.

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  • Stop 2 Kainui silt loam and Naike clay, Gordonton Rd

    Lowe, David J. (2008)

    Conference item
    University of Waikato

    At this stop are several remarkable features both stratigraphic and pedological, and a “two-storied” soil, the Kainui silt loam alongside (in just a few places) the Naike clay. Both soils are Ultisols. The sequence of tephra beds and buried soil horizons spanning about 1 million years was exposed in 2007 by road works.

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  • Guidebook for Pre-conference North Island Field Trip ‘Ashes and Issues’, 28-30 November, 2008

    Lowe, David J.

    Book
    University of Waikato

    Guidebook for Pre-conference North Island, New Zealand Field Trip ‘Ashes and Issues’, 28-30 November, 2008. The route goes progressively towards the locus of the most recently active volcanic centres in central North Island. Concepts of upbuilding pedogenesis in tephra-mantled terrains will be discussed. Topical issues relating to soil and water quality and land management of intensive horticulture, pastoral farming (especially dairying), plantation forestry and C budgeting and modelling, and municipal effluent disposal by land treatment, will be considered as well. The declining quality of water in lakes in the Rotorua region and in Lake Taupo (mainly as a result of increasing N and P), and large-scale land-use conversions from plantation forestry to dairy farming in the Taupo area, and implications, are examined on days 2 and 3 of the trip.

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  • Colin George Vucetich (1918–2007)—pioneering New Zealand tephrochronologist

    Lowe, David J.; Tonkin, Philip J.; Neall, Vincent E.; Palmer, Alan S.; Alloway, Brent V.; Froggatt, Paul C. (2008)

    Journal article
    University of Waikato

    Many Quaternarists, tephrochronologists, and soil scientists mourned the passing in New Zealand of Colin Vucetich—gentle mentor, pedologist, and pioneering tephrochronologist—on 25 April (Anzac Day), 2007. Colin was in his 89th year. As well as forming a 25-year partnership with W.A. “Alan” Pullar, with whom he published three classic papers on tephrostratigraphy based on field work undertaken by the pair largely in their own time, Colin inspired and mentored numerous postgraduates in his later career as an academic at Victoria University of Wellington. There he taught pedology, soil stratigraphy, and tephrochronology until his retirement as Reader (Associate Professor) in 1982. In retirement he was an honorary lecturer and supervisor at Massey University (Palmerston North) until 1991 (Fig. 1, Fig. 2 and Fig. 3).

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  • Kainui silt loam: how the lepard changed its spots

    Lowe, David J. (1991)

    Journal article
    University of Waikato

    The Kainui silt loam occurs on low rolling hills in the northern part of the Hamilton Basin, and is well expressed in Hamilton City.

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  • Alteration, formation, and occurrence of minerals in soils

    Churchman, G. Jock; Lowe, David J. (2012)

    Book item
    University of Waikato

    This chapter, like Churchman (2000), seeks to bring readers up to date with information and understanding about the alteration of minerals and the nature of their products in the context of the formation and development of soils. It complements various articles by Bergaya et al. (2006), and the recent books by Velde and Meunier (2008) and Velde and Barré (2010). This current chapter differs from Churchman (2000) in that it discusses the manner in which minerals, and especially secondary minerals, actually occur in soils, i.e., it deals (in Section 20.3) with the occurrence, as well as the alteration and formation of minerals in soils.

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  • Niwashi - a new tool for pedology and cover-bed stratigraphy in New Zealand

    Lowe, David J. (2000)

    Journal article
    University of Waikato

    The Japanese Niwashi - literally 'garden master' - is a new field tool for dressing soil profiles or cleaning down stratigraphic sections comprising sottish or unconsolidated cover-bed deposits. Used for many years by Japanese pedologists, tephrochronologists, and volcanologists, the Niwashi has now become available in New Zealand. We have tried it out on a range of soils and various deposits and found it to be an excellent tool for field work in many situations.

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  • Stratigraphy and reserves of pumiceous sand deposits in Perry's 'Asparagus Block' at Horotiu

    Nelson, Campbell S.; Lowe, David J.; Lootsma, A (1997)

    Report
    University of Waikato

    The stratigraphic relationships between the deposits of the Hinuera Formation and the Taupo Pumice Alluvium are described over a 16 ha plot of land known as the 'Asparagus Block' at Horotiu. The Hinuera Formation is exposed at the surface at the southern end of this block, and is overlain by a wedge of Taupo Pumice Alluvium which increases in thickness from 0 to 8 m northwards across the block. Lithofacies in the Hinuera Formation are dominated by trough cross-bedded gravelly sands (lithofacies AI), with common cross-laminated sands (lithofacies B) and massive to horizontally laminated silts (lithofacies D). The pumice content of these deposits is mainly 70%. Lithofacies in the Taupo Pumice Alluvium are dominated by horizontally to inclined (tabular cross-) bedded slightly gravelly sands and sands (lithofacies G 1/2), with common occurrences of horizontally bedded to massive sandy silts (lithofacies D). The pumice content of these Taupo deposits is high, typically >80%. Cross-sections are presented showing an interpreted subsurface distribution of these lithofacies from south to north through the 'Asparagus Block'. The estimated reserve of extractable pumice sand from the block is of the order of about 400,000 to 450,000 m³.

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  • Measuring radiation in the environment following the Fukushima nuclear disaster, Japan

    Lowe, David J. (2012)

    Journal article
    University of Waikato

    A group of scientists and technical staff from Toshiba Company, including Dr Hirokazu Kanai, undertook field trials at the station using a newly-developed, portable, two-dimensional gamma-ray visualization system known as a “Gamma Camera”.

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  • The Anthropocene: an Australasian perspective and survey.

    Lowe, David J.; Bostock, Helen C. (2015-06-02)

    Journal article
    University of Waikato

    In 2000, Crutzen and Stoermer suggested that the Holocene (the geological period of time since 11,700 years ago: Walker et al., 2009) had finished and that humanity had now entered the “Anthropocene”. As summarised by Steffen et al. (2011) and Wolfe et al. (2013), these scientists were referring to the Anthropocene as the interval of demonstrable human alteration of global biogeochemical cycles, beginning subtly in the late 18th Century following James Watt’s invention of the coal-fired steam engine, and accelerating markedly in the mid-20th Century (called “The Great Acceleration”).

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  • Application of new technology liquid scintillation spectrometry to radiocarbon dating of tephra deposits, New Zealand

    Lowe, David J.; Hogg, Alan G. (1992)

    Journal article
    University of Waikato

    Two major technological advances in the radiocarbon dating method have recently enhanced its potential application to tephra studies: the advent of accelerator mass spectrometry and the development of new technology liquid scintillation (LS) spectrometry. The new technology LS spectrometer represents a significant refinement of the conventional dating method based on liquid scintillation counting of benzene. It improves upon conventional LS counting by allowing spectral analysis, and by providing a high degree of counting stability and efficiency in an ultra low-level background radiation environment. These attributes enable radiocarbon dating with greater accuracy and statistical precision, and also allow the determination of both smaller and older samples than previously possible by conventional radiometric methods. The new Wallac Oy ‘Quantulus’ LS spectrometer has been in operation at the University of Waikato Radiocarbon Dating Laboratory since 1988. The instrument achieves ultra-low background levels by both passive and active forms of shielding. The shielding comprises a massive asymmetric passive lead shield surrounding an aticoincident liquid scintillation guard. In addition, the Quantulus contains dual multichannel analyzers which allow spectral analysis and ‘windowless’ data acquisition. The Quantulus LS spectrometers at the Waikato laboratory have been used to date a variety of carbonaceous materials associated with tephra deposits in New Zealand, ranging in age from ca. 0.1–55 ka. In particular, we have tested the capability of the Quantulus for determining ages of samples that are typically more difficult or impossible to date by conventional methods: (1) very young samples (e.g. Tarawera Tephra, erupted ca. 100 years ago); (2) older samples (e.g. Mangaone Tephra, erupted ca. 30 ka); and (3) samples containing only sparse carbon (e.g. lake sediments associated with tephra layers aged ca. 20 ka or less). The Quantulus LS spectrometer is both more accurate and precise (statistical counting errors are reduced) than conventional instruments, is capable of extending the limits of detection at both ends of the age scale, and has a smaller sample handling ability. Analyses can be obtained at comparatively low cost. Such advances are potentially beneficial to tephrochronology and volcanology and a wide range of applications in Quaternary research.

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  • Tephras and New Zealand archaeology

    Lowe, David J.; Newnham, Rewi M.; McFadgen, Bruce G.; Higham, Thomas F.G. (2000)

    Journal article
    University of Waikato

    Establishing an accurate date for earliest Polynesian settlement in New Zealand is essential for understanding patterns of settlement and associated environmental impacts, and the processes and rates of cultural change in Eastern Polynesia. Tephra deposits from five volcanic centres, together with exotic sea-rafted pumice, provide isochronous constraints on the timing of earliest settlement and human impacts in northern New Zealand. A local basaltic tephra from Rangitoto Island (Auckland) and locally distributed andesitic tephras from Egmont volcano directly date human occupation to c. AD 1400–1450. Distal andesitic tephras (Tufa Trig Formation) from Mt Ruapehu, Tongariro volcanic centre, help constrain the timing of earliest anthropogenic deforestation signals in Hawke's Bay. Sea-rafted Loisels Pumice(s), although of uncertain stratigraphic reliability in places, overlies cultural remains that can be no younger than c. AD 1350 along the east coast, North Island. The regionally extensive rhyolitic Kaharoa Tephra, which erupted from Okataina volcano between c. AD 1300–1390, is the critical “settlement layer” datum for dating prehistory in the North Island: no human artefacts are recorded beneath it and the earliest inferred environmental impacts by humans are dated to c. AD 1280, just prior to its deposition. This maximum date matches the earliest radiocarbon dates derived for both settlement and human impacts from archaeological and natural sites (c. AD 1250), and implies that the onset of deforestation was essentially contemporaneous with initial settlement. The widespread rhyolitic Taupo Tephra, which erupted from Taupo volcano c. AD 200, provides an isochronous benchmark well before earliest settlement. The tephra may coincide approximately with a putative earlier transient contact in New Zealand based on Pacific rat-bone (Rattus exulans) dates. More precise calendrical dates on the tephras—via dendrochronology or ice-core records or other dating methods—would help refine assessment of the timing of earliest settlement, while extending the distributional range of critical tephra layers, through application of crypto-tephra analysis, could lead to a greater understanding of settlement patterns.

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  • Quaternary environmental change in New Zealand: a review

    Newnham, Rewi M.; Lowe, David J.; Williams, Paul W. (1999)

    Journal article
    University of Waikato

    The discovery that orbital variations are the driving force behind Quaternary climate change provides an impetus to set local and regional records of environmental change into the global context, a principle that has been strongly embraced by Quaternary scientists working in New Zealand. Their major achievements and significant current initiatives are reviewed here. The importance of the New Zealand Quaternary stems from its geographical context: a climatically sensitive, remote oceanic, southern location spanning 17 degrees of the mid-latitudes; an obliquely convergent plate boundary setting resulting in a high mountain range athwart the prevailing westerlies, active volcanism, a youthful and dynamic landscape, and mountains high enough to maintain glaciers today; and a remarkably short prehistory. The resultant records show marked environmental changes due not only to climatic oscillations but also to vigorous, active tectonism and volcanism. The Taupo Volcanic Zone, containing the world's strongest concentration of youthful rhyolitic volcanoes, has produced at least 10 000 km3 of magma in the last 2 Ma. Climatic interpretations of records from marine sediments in the New Zealand region, together with several long sequences of alternating marine and terrestrial sediments, indicate broad synchrony with Northern Hemisphere events (within limitations of dating), although there are differences in detail for shorter-term climatic events. It is not yet certain that glacial advances coincided precisely with those in the Northern Hemisphere or were of similar duration. Late Cainozoic glaciation commenced c. 2.6-2.4 Ma but the record of glacial deposits is fragmentary and poorly dated except for the most recent events. The Last (Otira) Glaciation, from c. 100-10 ka, was characterized by at least five glacial advances including during the Last Glacial Maximum from 25 to 15 ka, when snowlines fell by 600-800 m. New Zealand evidence for cooling during the Younger Dryas stade is equivocal whilst isotopic records from speleothems, and other data, indicate warmer and wetter conditions from 10-7 ka, broadly conforming with records from mid-latitude Northern Hemisphere locations. Future advances will require sampling at shorter timescales, improvements in the accuracy and precision of existing dating methods and the development of new ones, extension of palaeoecological techniques to cover the full potential of New Zealand's diverse biota, and a stronger emphasis on quantification of palaeoclimatic parameters.

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  • Discriminant function analysis and correlation of Late Quaternary rhyolitic tephra deposits from Taupo and Okataina volcanoes, New Zealand, using glass shard major element composition

    Stokes, Stephen; Lowe, David J.; Froggatt, Paul C. (1992)

    Journal article
    University of Waikato

    Discriminant function analysis (DFA) is a multivariate statistical technique that provides a non-subjective means of correlating tephra deposits based on compositional or other variable characteristics. Using microprobe-determined glass shard major element composition, two DFA classification models were developed to separate (distinguish) individual tephra deposits erupted since ca. 22 ka from each of the rhyolitic Okataina and Taupo volcanoes, North Island, New Zealand. In an iterative approach, those tephras easily classified in the first DFA are removed from the dataset before applying the second DFA, hence generally improving the separation of the remaining tephras that are more closely alike. The first two canonical functions accounted for ca. 85% of variance within the Okataina dataset, and ca. 80% within the Taupo dataset. Using the first two canonical variates, we correctly classified 5 (Kaharoa, Rotoma, Waiohau, Rotorua, Te Rere) of the Okataina, and 4 (Taupo, Hatepe, Whakaipo, Karapiti) of the Taupo deposits under study, at efficiency levels of 70–100%. The incorporation of a third canonical variate, and additional sompositional data, would further improve our DFA models, which should ideally be used in conjunction with stratigraphic and other characteristic indices, where available, to facilitate accurate correlation. The Mahalanobis distance statistic (D²), a statistical measure of the multidimensional spacing of individual analyses, or groups of analyses, provides a better measure of likeness than the frequently used but subjective similarity coefficients technique.

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  • Testing the synchroneity of pollen signals using tephrostratigraphy

    Newnham, Rewi M.; Lowe, David J. (1999)

    Journal article
    University of Waikato

    Since the advent of radiocarbon dating, the concept of synchronous pollen-vegetation events extending across broad regions such as the British Isles, which had emerged from earlier pollen-stratigraphic studies, has been largely refuted. Nevertheless the assumption that pollen profiles within a geographically coherent area should exhibit broadly comparable and synchronous pollen signals still holds currency among some palynologists. This assumption is tested here by comparing pollen spectra between lateglacial and postglacial sites in northern New Zealand, until recently unaffected by human activity, where independent correlations are obtained by tephrochronology. At sites of similar size, morphology, and depositional environment within the same phytogeomorphic region, it is possible to achieve accurate palynological correlations, provided local taxa and those representing ecologically disparate source species are omitted from the pollen datasets. However, anomalous correlations may still occur and are more likely when sites with different depositional environments or at greater distances are compared. These results suggest that the concept of synchronous pollen signals, even between nearby sites with similar depositional setting, is not universally applicable and it is possible that erroneous palynostratigraphic correlations have been made in the past.

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  • Unravelling upbuilding pedogenesis in tephra and loess sequences in New Zealand using tephrochronology

    Lowe, David J.; Tonkin, Philip J. (2010)

    Journal article
    University of Waikato

    The genesis of soils developed in either tephra or loess on stable sites differs markedly from that of soils developed on rock because classical topdown processes operate in conjuction with geological processes whereby material is added to the land surface so that the soils form by upbuilding pedogenesis. Understanding the genesis of such soils (typically Andisols and Alfisols, respectively) often requires a stratigraphic approach combined with an appreciation of buried soil horizons and polygenesis. In New Zealand, calendrically-dated tephras provide an advantage for assessing rates of upbuilding through chronostratigraphy. Many Andisol profiles form by upbuilding pedogenesis as younger tephra materials are deposited on top of older ones. The resultant profile character reflects interplay between the rate at which tephras are added to the land surface and topdown processes that produce andic materials and horizons. In loess terrains, upbuilding pedogenesis since c. 25,000 years ago is associated with maximum rates of loess accumulation c. 3 10 mm per century, sufficiently slow for soil-forming processes to continue to operate as the land surface gradually rises. Thus, Alfisol subsoil features are only weakly developed and Bw or B(x) horizons typically are formed. In contrast, topdown pedogenesis is associated with minimal or zero loess accumulation, the land surface elevation remains essentially constant, and subsoil features become more strongly developed and Bg, Bt, or Bx horizons typically are formed.

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  • Impacts of deforestation and burning, and the role of bracken fern, on the properties of surficial or buried soil A-horizons

    Lowe, David J.; McDaniel, Paul (2008)

    Conference item
    University of Waikato

    Bracken fern (Pteridium spp.) is an aggressive plant that commonly invades disturbed sites. Its success as an invader is attributable, in part, to its ability to produce abundant growth, both below ground in the form of rhizomes and fine roots and above ground as fronds and stems. This biomass production has been shown to affect numerous soil properties. In describing soils of the „Pumice Lands‟ (Pumice Soils or Vitrands mainly) in New Zealand, Molloy and Christie (1998) attributed black A horizons „to bracken fern, which replaced much of the forest‟. Analyses of humus and phytoliths in the A horizons of soils developed especially on Kaharoa and Taupo tephras in central North Island (buried beneath 1886 Tarawera eruptives in the Rerewhakaaitu area) showed that type-A humic acids predominated and that fernland and grassland had replaced the pre-existing forests (Birrell et al., 1971; Sase et al., 1988; Hosono et al., 1991; Sase and Hosono, 1996). Pollen, phytolith and associated studies, together with tephrochronology, have shown that human-induced deforestation by burning began in New Zealand soon after Polynesian settlers arrived (e.g. McGlone, 1989; Clarkson et al., 1992; Kondo et al., 1994; McGlone et al., 1994; Newnham et al., 1998; McGlone and Wilmshurst, 1999; Watanabe and Sakagami, 1999; see also article on Polynesian settlement by Lowe, this volume). The repeated burning resulted in the formation of extensive fernlands (McGlone et al., 2005).

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  • Old bones tell new tales

    Lowe, David J. (2006)

    Journal article
    University of Waikato

    Of all the so-called evidence that has been presented in support of human settlement in New Zealand before the second millennium, only a set of radiocarbon-dated rat bones has appeared scientifically credible. Now even that is coming under close scrutiny.

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  • Connecting with tephras: principles, functioning, and applications of tephrochronology in Quaternary science

    Lowe, David J. (2013)

    Conference item
    University of Waikato

    Tephrochronology is a unique method for linking and dating geological, palaeoecological, palaeoclimatic, or archaeological sequences or events. The method relies firstly on stratigraphy and the law of superposition, which apply in any study that connects or correlates deposits from one place to another. Secondly, it relies on characterising and hence identifying or ‘fingerprinting’ tephra layers using either physical properties evident in the field or those obtained from laboratory analysis, including mineralogical examination by optical microscopy or geochemical analysis of glass shards or crystals (e.g., Fe-Ti oxides, ferromagnesian minerals) using the electron microprobe and other tools. Thirdly, the method is enhanced when a numerical age is obtained for a tephra layer by (1) radiometric methods such as radiocarbon, fission-track, U-series, or Ar/Ar dating, (2) incremental dating methods including dendrochronology or varved sediments or layering in ice cores, or (3) age-equivalent methods such as palaeomagnetism or correlation with marine oxygen isotope stages or palynostratigraphy. Once known, that age can be transferred from one site to the next using stratigraphic methods and by matching compositional characteristics, i.e., comparing ‘fingerprints’ from each layer. Used this way, tephrochronology is an age-equivalent dating method.

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