6 results for Palmer, J.

  • A dendrometer band study of the seasonal pattern of radial increment in kauri (Agathis australis) ( New Zealand).

    Palmer, J.; Ogden, J. (1983)

    Journal article
    The University of Auckland Library

    Simple dendrometer bands were used to measure the radial increment of kauri (Agathis australis Salisb.) at 3 sites to the south and east of Auckland during the 1980-81 growing season. Diameter increment cores taken from some of the trees at the beginning and end of the study showed that the radial expansion measured by the bands correlated significantly (P<0.001) with the width of the annual ring formed over the same period. A reduction in tree growth rate during summer drought was recorded at 2 mid-altitude sites, but not near the altitudinal limit of kauri. These growth patterns were attributed to the different soil moisture conditions at the different sites.

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  • A palynological study of Polynesian and European effects on vegetation in Coromandel, New Zealand, showing the variability between four records from a single swamp

    Byrami, M.; Ogden, J.; Horrocks, M.; Deng, Y.; Shane, P.; Palmer, J. (2002)

    Journal article
    The University of Auckland Library

    An open access copy of this article is available from the publishers website. Seven cores were extracted from a river terrace swamp in the forested Kauaeranga valley, Coromandel Peninsula, New Zealand. High-resolution (c. 36-73 yr interval) pollen records were obtained from four of the cores and aged by radiocarbon dating and with stratigraphic reference to the 665 � 15 14C yr BP Kaharoa Tephra. The records span the last c. 1800 yr and show that the vegetation consisted of lowland podocarp-hardwood forest before deforestation by burning occurred. The pattern of deforestation at Kauaeranga, indicated by the abrupt dominance of Pteridium with concurrent increased charcoal, is typical of pollen records associated with early Polynesian settlement in New Zealand. Peaks of Pteridium and charcoal were also found in sediments deposited after European settlement. Different cores show marked palynological and stratigraphic differences relative to the Kaharoa Tephra, most importantly with regard to the timing of deforestation. Deforestation occurred close to the Kaharoa, at a calculated age of c. 750 BP in one core but well above the Kaharoa (c. 480 BP) in another. The stratigraphic unconformities between cores are attributed to variable fluvial processes causing an uneven deposition of sediments within the swamp.

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  • Dendroclimatic interpretation of tree-rings in Agathis australis (kauri): 2. Evidence of a significant relationship with ENSO

    Fowler, A.; Palmer, J.; Salinger, J.; Ogden, J. (2000)

    Journal article
    The University of Auckland Library

    An open access copy of this article is available from the publishers website. Part I of this investigation (Buckley et al. 2000) found consistent significant correlations between tree growth and climate for nine New Zealand kauri tree-ring chronology sites. The nature of these correlations suggests that Agathis australis (kauri) may carry a useful signal of the El Nino-Southern Oscillation (ENSO) phenomenon. We have explored the potential of kauri for ENSO reconstruction through statistical analysis of the relationship between the Southern Oscillation Index (SOI) and the tree-ring indices previously derived. Results showed a consistent SOI-kauri growth relationship for eight of the nine sites. A significant negative correlation was found between kauri growth and concurrent seasonal mean SOI, and a positive correlation with the seasonal mean SOI recorded over the preceding two years. The former is consistent with a hypothesised ENSO-kauri growth model, but the two-year lag suggests an additional relationship, perhaps associated with kauri phenology. Decadal-scale variability was evident in the strength of the SOI-kauri growth relationships, particularly in autumn (March-May) and winter (June-August). Comparison of SOI and extreme kauri growth years indicated general consistency in the growth response to ENSO, but also identified some anomalies, suggesting that kauri ring-width is an imperfect ENSO proxy. However, combined with the spatial scale at which ENSO operates, and the known variability of links with regional climates, we conclude that kauri growth-rings could provide a useful ENSO proxy, particularly within the context of multi-proxy spatially distributed studies.

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  • Dendroclimatic interpretation of tree-rings in Agathis australis (kauri). 1. Climate correlation functions and master chronology

    Buckley, B.; Ogden, J.; Palmer, J.; Fowler, A.; Salinger, J. (2000)

    Journal article
    The University of Auckland Library

    An open access copy of this article is available from the publishers website. In this paper we analyse nine existing Agathis australis (kauri) chronologies for their response to climate, and compare our results with those of previous studies. We update the southernmost chronology, from Katikati, which now extends to the 1997 growth ring (1997-98 growing season in Southern Hemisphere). We also employ recent standardisation procedures that have been demonstrated to eliminate the chance of biasing the chronology indices. Climate correlation functions are generated for all nine kauri chronologies, by correlating chronology indices with meteorological datasets. In an earlier study only a 12 month response window was analysed, combined with lagging the growth year in order to account for prior-season growth response. Our expanded dendroclimatic response window covers the 21 months from May of the year of growth (t), back to the previous September (year t - 1). There are consistent significant correlations with climate for all nine kauri sites, most pronounced in the form of a positive response in season t to precipitation in the previous season (t - 1), and an inverse response to temperature in the year of growth. The most robust climate signal comes from the Katikati chronology, which has been updated by 16 years to the 1997 growth ring. The additional years allow for more degrees of freedom and a better estimate of the climate correlation functions. Correlation and Principal Component Analyses validate the combining of eight of the nine chronologies into one regional time series. The results presented in this paper are encouraging for future dendroclimatic research with Agathis australis, towards the goal of long-term reconstruction of climate.

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  • Variations in sandstone diagenesis with depth, time, and space, onshore Taranaki wells, New Zealand

    Smale, D.; Mauk, J.L.; Palmer, J.; Soong, R.; Blattner, P. (1999)

    Journal article
    The University of Auckland Library

    An open access copy of this article is available from the publishers website. Study of diagenesis in cores from Kapuni Field, Waihapa-2, Kaimiro-2, and New Plymouth-2 shows many expected features-quartz and feldspar dissolution and precipitation, clay mineral precipitation, and carbonate dissolution and precipitation. Local variations may overprint broader trends; early quartz overgrowth in parts of the basin is not recognisable in Kapuni wells, and feldspars may be etched differentially. In the Kapuni Group, early siderite precipitated from pore waters similar to those in which the host sediment was deposited, whereas late calcite was probably deposited from fresh water. In the Moki Formation, some calcite may be similarly late, but variations in pH modified deposition. Cathodoluminescence of new growth of calcite and quartz shows considerable variety, and some luminescent and non-luminescent quartz have grown contemporaneously. Most stable isotope data show regular trends. Petroleum has migrated within the Taranaki Basin at least twice: once during early diagenesis of the Kapuni Group, and later after diagenetic mineral growth had occurred. Deep sandstones of the Farewell Formation in the Kapuni Field, though now virtually impermeable, probably passed through a period of diagenetically modified porosity that allowed migration of early hydrocarbons.

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  • Herbivore damage and leaf loss in the New Zealand pepper tree ('Kawakawa'; Macropiper excelsum; Piperaceae)

    Hodge, Simon; Keesing, V.; Wratten, Stephen D.; Lovei, G.; Palmer, J.; Cilgi, T.

    Journal article
    Lincoln University

    The pattern of herbivore damage on the New Zealand pepper tree (kawakawa; Macropiper excelsum) caused by its main insect herbivore (Cleora scriptaria) was investigated in the field and laboratory. In the field, only a small proportion of kawakawa leaves had no herbivore damage and C. scriptaria typically produced a number of small holes in each leaf. Leaves were shed at a rapid rate but leaf shedding was not increased by higher levels of herbivore damage. Some older leaves had less damage than would be expected for their age, possibly suggesting some variation in leaf susceptibility to herbivory. The effect of previous leaf damage on subsequent herbivory was examined in the field and laboratory. On no occasion did artificial leaf damage, or herbivory by larvae of the same or another species, affect the edibility of leaves to C. scriptaria. The results suggest that leaf shedding by kawakawa was not primarily a response to herbivore damage and induced defences against herbivores could not be demonstrated in this system.

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