Auckland occupies a climatically sensitive position close to a major biogeographic boundary in the southern mid‐latitudes. A new pollen record from Kohuora maar crater, Auckland, displays vegetation and climatic changes for the past ca. 32 000 years. Of particular interest are the inferred climatic patterns for the first part of the interval, encompassing the Last Glacial Maximum (LGM). The Kohuora record corresponds closely with pollen records from other Auckland sites indicating that the patterns observed are at least regional in extent. It is also broadly consistent with a variety of palaeoenvironmental evidence from across New Zealand, including the glacial record from Westland, other palynological records from North Island, other palaeoecological records from the South Island, and aeolian quartz sequences from western North Island. These records show that glacial conditions prevailed across most, if not all, of New Zealand during the interval ca. 29–19 k cal. yr BP, longer and earlier than the LGM sensu stricto. We suggest that the term extended LGM (eLGM) may be more appropriate for the New Zealand region. Within this predominantly cold interval, the Auckland pollen records indicate a climatic amelioration for the interval ca. 26–24 k cal. yr BP, also consistent with other palaeocological data from Canterbury, that fall within a period of climate amelioration recognised between the first two eLGM glacial advances in Westland. We refer to this warming interval as the eLGM Interstadial. The ca. 27 k cal. yr BP Kawakawa/Oruanui tephra is instrumental in most of these inter‐site comparisons and occurs after the first peak of eLGM cooling in a short‐lived comparatively mild phase. A subsequent return to apparently colder climate in the Auckland records may indicate a volcanic cooling effect or, more likely, widespread landscape disturbance following this major eruption event. Strong correspondence between biotic responses, glacial fluctuations and aeolian quartz deposition linked to major shifts in strength and latitudinal extent of the southern westerlies suggest that both the eLGM and eLGM Interstadial may be more widely registered, at least across the Southern Ocean. Support for this assertion comes from parallel investigations in western and southernmost South America and isotopic and palaeoecological records from Southern Ocean marine cores. Recent reconstructions of the globally averaged ice‐equivalent sea‐level history are in line with this evidence from the Southern Hemisphere, suggesting that the eLGM may have a global registration. In light of these observations, we suggest a re‐examination of the defined timing of the LGM along with renewed effort to establish climatic patterns during this period and understand their causes. Copyright © 2007 John Wiley & Sons, Ltd.
This paper examines the literature on research into the effects of burial by deposition of blown sand, volcanic deposits (tephra, lavas and lahars) or fluvial sediment on vegetation and the subsequent capacity of the vegetation for survival and regeneration. Research on this topic involves the understanding and skills of the biogeographer, the ecologist and the geomorpholo-gist and represents a potentially very interesting area for integration between these areas of physical geography. Burial is closely linked to concepts of plant succession and pedogenesis. A general model of burial stress is presented that shows how types of stress are linked to the burial environment and the characteristics of the burial event, in particular the magnitude and frequency. The importance of elasticity of response of species to burial is vital, as demonstrated by the evolution of certain species, such as those of the genus Ammophila in sand dunes that appear to respond positively to the burial process. Research into burial by dust deposition, by volcanic tephra and lavas, by sand in coastal and lake dune environments, in desert environments and by alluvium and ‘run-on’ following hydro-logical events are reviewed in turn. The significance of burial to palaeoenvironmental and palaeoecological research is then demonstrated by reference to machair sand dune stratification in the Outer Hebrides and vegetation damage and burial following proximal volcanic impacts in New Zealand. Finally, methods of experimental research into burial in both the field and in the greenhouse are summarized and the conclusion stresses the need for more holistic approaches to the study of burial that link the biogeographical aspects of plant ecophysiology and both individual species and community ecology to the various geomorphic processes of deposition and sedimentation.
Palynological evidence was used to determine the development of vegetation communities on Matakana Island, North Island, New Zealand, over the last 1000 radiocarbon years. The pollen record indicates that changes occurred in the vegetation immediately following fallout deposition of the Kaharoa Tephra approximately 100 km from source at c. 665 years BP. Such changes may be a direct response to the impact of tephra fall, although the possibility of anthropogenic disturbance cannot be discounted. As a result of the eruption some taxa (Leucopogon fasciculatus and Tupeia antarctica) became at least temporarily extinct from the area. Two phases of anthropogenic influence on the environment are recorded in the pollen record: Polynesian, followed by European inhabitation of the island, giving a detailed history of human influence in the area for the millennium.
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