Macropaleobotany of the Miocene Manuherikia Group of New Zealand.
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Four ferns (including Blechnum and Pneumatopteris ) occur as macrofossils in the Lower Miocene Manuherikia Group (of fluvial-lacustrine origin) of Central Otago, New Zealand. There are also 4 conifers (Araucaria, Dacrycarpus, Decussocarpus, and Podocarpus ), 32 taxa of "broadleaved" angiosperms (including Eucalyptus, Metrosideros, Muehlenbeckia, Nothofagus, Ripogonum, Elaeocarpaceae, and Lauraceae), one palm (including vegetative material, fruits, and -flower-heads), Leguminosae remains (including bipinnate leaves and fruits containing seeds) and a variety of other reproductive organs (including those ascribed to Casuarina, Eucalyptus, Cunoniaceae, and possibly Proteaceae). Most taxa are now extinct in New Zealand at the species or generic level.
Material (over 3300 specimens) was collected at 53 individual localities throughout the Manuherikia Group. The floras coming from many localities show significant taxonomic differences. The floras are compared with extant physiognomic types occurring in Australia, and on this basis individual plant assemblages are indicative of podocarp notophyll vine forest, araucarian notophyll vine forest, microphyll fern forest (or microphyll vine forest), simple notophyll evergreen vine forest, notophyll feather palm vine forest, and tall open-forest, at times probably closed forest with sclerophyll emergents.
Fire is postulated as an important ecological agent in part accounting for these differences, but water-table, rainfall, temperature, and soil fertility were also involved. Climate varied throughout the time of accumulation of the fossil deposits but was broadly similar to that of forested regions in New Zealand today, sometimes warmer, but not tropical. The changing floras throughout two closely spaced, 90 m thick stratigraphic sequences reflect an initially temperate forest, in which Nothofagus was important, progressing to Araucaria and then Eucalyptus vegetation. The succession was a response to decreasing rainfall and increasing fire-frequency. A dramatic increase in rainfall and probably temperature led to the development of subtropical rainforest. Rainfall continued to fluctuate, with periods of increased fire-frequency dominated by Eucalyptus , then rainforest vegetation was reestablished.
The flora as a whole was part of a vegetation which was originally widespread over the Australasian region. New Zealand's present vegetation may not be in equilibrium with its climate and its "distinctiveness" probably results from effects of the ice-age.
A taxonomic method is adopted whereby leaves and ferns are given parataxon code-names, and those which are confidently identified are also given Linnaean Latin names. A new terminology of leaf architecture is presented which is used in the systematic descriptions. Identification of the material is based on herbarium material collected in New Zealand, Tasmania, north Queensland, Papua New Guinea, and New Caledonia.
Material (over 3300 specimens) was collected at 53 individual localities throughout the Manuherikia Group. The floras coming from many localities show significant taxonomic differences. The floras are compared with extant physiognomic types occurring in Australia, and on this basis individual plant assemblages are indicative of podocarp notophyll vine forest, araucarian notophyll vine forest, microphyll fern forest (or microphyll vine forest), simple notophyll evergreen vine forest, notophyll feather palm vine forest, and tall open-forest, at times probably closed forest with sclerophyll emergents.
Fire is postulated as an important ecological agent in part accounting for these differences, but water-table, rainfall, temperature, and soil fertility were also involved. Climate varied throughout the time of accumulation of the fossil deposits but was broadly similar to that of forested regions in New Zealand today, sometimes warmer, but not tropical. The changing floras throughout two closely spaced, 90 m thick stratigraphic sequences reflect an initially temperate forest, in which Nothofagus was important, progressing to Araucaria and then Eucalyptus vegetation. The succession was a response to decreasing rainfall and increasing fire-frequency. A dramatic increase in rainfall and probably temperature led to the development of subtropical rainforest. Rainfall continued to fluctuate, with periods of increased fire-frequency dominated by Eucalyptus , then rainforest vegetation was reestablished.
The flora as a whole was part of a vegetation which was originally widespread over the Australasian region. New Zealand's present vegetation may not be in equilibrium with its climate and its "distinctiveness" probably results from effects of the ice-age.
A taxonomic method is adopted whereby leaves and ferns are given parataxon code-names, and those which are confidently identified are also given Linnaean Latin names. A new terminology of leaf architecture is presented which is used in the systematic descriptions. Identification of the material is based on herbarium material collected in New Zealand, Tasmania, north Queensland, Papua New Guinea, and New Caledonia.
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xiv. 403p. Ill. Map in text. 30cm.
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1989Pole
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POLYGON ((168.47976900653137 -45.393157301963868,168.547227843796463 -44.629278243820963,171.253617329301051 -44.750450922525935,171.212104694564601 -46.004636504752746,169.244768202053365 -45.944214824635985,169.239010790357526 -45.421978855029877,168.47976900653137 -45.393157301963868))
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Pole, M.S., “Macropaleobotany of the Miocene Manuherikia Group of New Zealand.,” Otago Geology Theses, accessed December 7, 2024, https://theses.otagogeology.org.nz/items/show/235.