List of Titles

A new perspective on Late Eocene and Oligocene vegetation and paleoclimates of South-eastern Australia

- Sluiter, Ian, Holdgate, Guy, Reichgelt, Tammo, Greenwood, David, Kershaw, A. P., Schultz, Nick

Authors: Sluiter, Ian , Holdgate, Guy , Reichgelt, Tammo , Greenwood, David , Kershaw, A. P. , Schultz, Nick
Date: 2022
Type: Text , Journal article
Relation: Palaeogeography, Palaeoclimatology, Palaeoecology Vol. 596, no. (2022), p.
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Description: We present a composite terrestrial pollen record of latest Eocene through Oligocene (35.5–23 Ma) vegetation and climate change from the Gippsland Basin of south-eastern Australia. Climates were overwhelmingly mesothermic through this time period, with mean annual temperature (MAT) varying between 13 and 18 °C, with an average of 16 °C. We provide evidence to support a cooling trend through the Eocene–Oligocene Transition (EOT), but also identify three subsequent warming cycles through the Oligocene, leading to more seasonal climates at the termination of the Epoch. One of the warming episodes in the Early Oligocene appears to have also occurred at two other southern hemisphere sites at the Drake Passage as well as off eastern Tasmania, based on recent research. Similarities with sea surface temperature records from modern high southern latitudes which also record similar cycles of warming and cooling, are presented and discussed. Annual precipitation varied between 1200 and 1700 mm/yr, with an average of 1470 mm/yr through the sequence. Notwithstanding the extinction of Nothofagus sg. Brassospora from Australia and some now microthermic humid restricted Podocarpaceae conifer taxa, the rainforest vegetation of lowland south-eastern Australia is reconstructed to have been similar to present day Australian Evergreen Notophyll Vine Forests existing under the sub-tropical Köppen-Geiger climate class Cfa (humid subtropical) for most of the sequence. Short periods of cooler climates, such as occurred through the EOT when MAT was ~ 13 °C, may have supported vegetation similar to modern day Evergreen Microphyll Fern Forest. Of potentially greater significance, however, was a warm period in the Early to early Late Oligocene (32–26 Ma) when MAT was 17–18 °C, accompanied by small but important increases in Araucariaceae pollen. At this time, Araucarian Notophyll/Microphyll Vine Forest likely occurred regionally. © 2022 Elsevier B.V.

Dealing with Trade-Offs in destructive sampling designs for occupancy surveys

- Canessa, Stefano, Heard, Geoffrey, Robertson, Peter, Sluiter, Ian

Authors: Canessa, Stefano , Heard, Geoffrey , Robertson, Peter , Sluiter, Ian
Date: 2015
Type: Text , Journal article , Review
Relation: PLoS ONE Vol. 10, no. 3 (2015), p. e0120340
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Description: Occupancy surveys should be designed to minimise false absences. This is commonly achieved by increasing replication or increasing the efficiency of surveys. In the case of destructive sampling designs, in which searches of individual microhabitats represent the repeat surveys, minimising false absences leads to an inherent trade-off. Surveyors can sample more low quality microhabitats, bearing the resultant financial costs and producing wider-spread impacts, or they can target high quality microhabitats were the focal species is more likely to be found and risk more severe impacts on local habitat quality. We show how this trade-off can be solved with a decision-theoretic approach, using the Millewa Skink Hemiergis millewae from southern Australia as a case study. Hemiergis millewae is an endangered reptile that is best detected using destructive sampling of grass hummocks. Within sites that were known to be occupied by H. millewae, logistic regression modelling revealed that lizards were more frequently detected in large hummocks. If this model is an accurate representation of the detection process, searching large hummocks is more efficient and requires less replication, but this strategy also entails destruction of the best microhabitats for the species. We developed an optimisation tool to calculate the minimum combination of the number and size of hummocks to search to achieve a given cumulative probability of detecting the species at a site, incorporating weights to reflect the sensitivity of the results to a surveyor's priorities. The optimisation showed that placing high weight on minimising volume necessitates impractical replication, whereas placing high weight on minimising replication requires searching very large hummocks which are less common and may be vital for H. millewae. While destructive sampling methods are sometimes necessary, surveyors must be conscious of the ecological impacts of these methods. This study provides a simple tool for identifying sampling strategies that minimise those impacts. © 2015 Canessa et al.

Diatom-salinity relationships in wetlands: Assessing the influence of salinity variability on the development of inference models

- Tibby, John, Gell, Peter, Fluin, J., Sluiter, Ian

Authors: Tibby, John , Gell, Peter , Fluin, J. , Sluiter, Ian
Date: 2007
Type: Text , Journal article
Relation: Hydrobiologia Vol. 591, no. 1 (2007), p. 207-218
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Description: Diatoms are among the most widely used indicators of human and climate induced wetland salinity history in the world. This is particularly as a result of the development of diatom-based models for inferring past salinity. These models have primarily been developed from relationships between diatoms and salinity measured at the time of sampling or during the preceding year. Although within site variation in salinity has the potential to reduce the efficacy of such models, its influence has been rarely considered. Hence, diatom-conductivity relationships in eight seasonally monitored wetlands have been investigated. In developing a diatom-conductivity transfer function from these sites, we sought to assess the influence of conductivity variation on diatom inference model performance. Our sites were characterised by variability in conductivity that was not correlated to its range and thus were well suited to an investigation of this type. We found, contrary to expectations, that short-term (seasonal) changes in conductivity which were often dramatic did not result in unduly reduced transfer function performance. By contrast, sites that were more variable in the medium term (5-6 years) tended to have larger model errors. In addition, we identified a secondary ecological gradient in the diatom data which could not be related to any measured variable (including pH, turbidity or nutrient concentrations).

Eocene-Miocene carbon-isotope and floral record from brown coal seams in the Gippsland Basin of southeast Australia

- Holdgate, Guy, McGowran, Brian, Fromhold, Thomas, Wagstaff, Barbara, Gallagher, Stephen, Wallace, Malcolm, Sluiter, Ian, Whitelaw, Michael

Authors: Holdgate, Guy , McGowran, Brian , Fromhold, Thomas , Wagstaff, Barbara , Gallagher, Stephen , Wallace, Malcolm , Sluiter, Ian , Whitelaw, Michael
Date: 2009
Type: Text , Journal article
Relation: Global and Planetary Change Vol. 65, no. 1-2 (2009), p. 89-103
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Description: The carbon-isotope and palynological record through 580Â m thick almost continuous brown coal in southeast Australia's Gippsland Basin is a relatively comprehensive southern hemisphere Middle Eocene to Middle Miocene record for terrestrial change. The carbon isotope Î´13Ccoal values of these coals range from - 27.7â€° to - 23.2. This isotopic variability follows gymnosperm/angiosperm fluctuations, where higher ratios coincide with heavier Î´13C values. There is also long-term variability in carbon isotopes through time. From the Eocene greenhouse world of high gymnosperm-heavier Î´13Ccoal values, there is a progressive shift to lighter Î´13Ccoal values that follows the earliest (Oi1?) glacial events around 33Â Ma (Early Oligocene). The overlying Oligocene-Early Miocene brown coals have lower gymnosperm abundance, associated with increased %Nothofagus (angiosperm), and lightening of isotopes during Oligocene cooler conditions. The Miocene palynological and carbon-isotope record supports a continuation to the Oligocene trends until around the late Early Miocene (circa 19Â Ma) when a warming commenced, followed by an even stronger isotope shift around 16Â Ma that peaked in the Middle Miocene when higher gymnosperm abundance and heavier isotopes prevailed. The cycle between the two major warm peaks of Middle Eocene and Middle Miocene was circa 30Â Ma long. This change corresponds to a fall in inferred pCO2 levels for the same period. The Gippsland data suggest a link between gymnosperm abundance, long-term plant Î´13C composition, climatic change, and atmospheric pCO2. Climatic deterioration in the Late Miocene terminated peat accumulation in the Gippsland Basin and no further significant coals formed in southeast Australia. The poor correspondence between this terrestrial isotope data and the marine isotope record is explained by the dominant control on Î´13C by the gymnosperm/angiosperm abundance, although in turn this poor correspondence may reflect palaeoclimate control. From the brown coal seam dating, the coal appears to have accumulated during a considerable part of the allocated 30Â Ma Cenozoic time period. These brown coal carbon isotope and palynological data appear to record a more gradual atmospheric carbon isotope change compared to the marine record. © 2008 Elsevier B.V. All rights reserved.

Eocene-Oligocene coals of the Gippsland and Australo-Antarctic basins – Paleoclimatic and paleogeographic context and implications for the earliest Cenozoic glaciations

- Holdgate, Guy, Sluiter, Ian, Taglieri, Jessica

Authors: Holdgate, Guy , Sluiter, Ian , Taglieri, Jessica
Date: 2017
Type: Text , Journal article , Review
Relation: Palaeogeography, Palaeoclimatology, Palaeoecology Vol. 472, no. (2017), p. 236-255
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Description: Australia's Gippsland Basin contains a semi-continuous Eocene-Oligocene (41.5–28.4 Ma) near-coastal coal record that formed adjacent to Pacific Ocean. Traralgon and Morwell Formation brown coals include 4 main seams (T2, T1, T0, M2). Coal seam palynology records show late Middle Eocene (T2) coals formed under megathermic conditions characterized by high-gymnosperm contents, Late Eocene (T1) coals formed under mesothermic conditions characterized by reduced-gymnosperm contents and earliest indications of palaeoclimate cooling. Earliest Oligocene T0 coal record (33.9–31.5 Ma) contains high-gymnosperm palynology profile, very similar to the T2 coals. The earliest indication of cooler climes only begins after this coal formed as indicated by low-gymnosperm high-Nothofagus (southern beech) pollen proportions. We suggest in Gippsland the earliest evidence for major glacial cooling (by inference the Oi1 event) be placed immediately above the T0 coal seam where Early to Late Oligocene Morwell Formation sands, clays and coals contain low counts of gymnosperms (< 10%) but high average proportions of Nothofagus (50%). This is the main definitive indicator that palaeoclimates had cooled between the Eocene and Oligocene. This agrees with the current ocean drilling position of the earliest (Oi1) glacial event shortly above the Eocene-Oligocene boundary. A number of contemporaneous Middle to Late Eocene brown coals occurred in near-coastal settings across 1200 km of southern Australia. Palaeogeographically, all these coal basins faced the Australo-Antarctic Gulf and have a much lower gymnosperm proportion (< 10%), low Nothofagus proportion (< 10%), but very high (non-Nothofagus) angiosperms proportion. This suggests a different climatic regime separated a cooler and wetter Gippsland Basin flora that responded to the cooler Proto-Ross Sea Gyre rotating around a wide Pacific Ocean, and a warm-wet climate associated with a warm proto-Leeuwin current of the Australo-Antarctic Gulf. © 2017 Elsevier B.V.

Fire and Late Oligocene to Mid-Miocene peat mega-swamps of south-eastern Australia : A floristic and palaeoclimatic interpretation

- Sluiter, Ian, Blackburn, David, Holdgate, Guy

Authors: Sluiter, Ian , Blackburn, David , Holdgate, Guy
Date: 2016
Type: Text , Journal article , Conference paper
Relation: Australian Journal of Botany Vol. 64, no. 8 (2016), p. 609-625
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Description: This article is a presentation that formed part of the Ecological Society of Australia's annual symposium entitled "Fire in Australia : how was the biota prepared for human occupation". The Late Oligocene to Mid-Miocene (25-13million years ago) brown coals of the Gippsland Basin in southern Victoria, Australia, were deposited in peat mega-swamps, unlike any in the world at the present day. The swamps preserve a rich botanical suite of macro- and microfossils, many of which can be identified with plant genera and families present today in Australia, New Caledonia, New Zealand and New Guinea. The peat-forming environments also preserve evidence of past burning in the form of micro-charcoal as well as macro-charcoal, the latter being evident as regional lenses or layers of fusinite, generally in coals of the darkest colour termed dark lithotypes. The presence of micro-charcoal in dark and some other lighter lithotypes indicated that fires also burnt locally, although they may have been extinguished before regional-scale burning occurred. It is also feasible that some peat mega-swamp plant communities dominated by rainforest angiosperm plants may have been fire excluders and prevented widespread fires from developing. Pollen and macrofossil evidence is presented of a distinctive southern conifer and angiosperm flora with an open canopy, primarily associated with the darkest coals that formed in the wettest parts of the peat-forming environment. Elsewhere, swamp forests with a large rainforest component grew on swamps raised appreciably above the regional groundwater table in a structural context akin to the ombrogenous peats of tropical coastal Sumatra and Sarawak. These vegetation types were not fire prone, but may have occasionally burnt at a local scale or at forest margins. Evidence is presented for the existence of seasonal climatic conditions that would appear to have facilitated a drying-out of the peat swamps in the warmest months of the year. A mesothermal climate was invoked where mean annual precipitation was at least 1500mm, and possibly as much as 2000mm, and mean annual temperatures were ∼19°C. © 2013 CSIRO.

On the distribution, ecology and conservation status of three rare plant taxa Zygophyllum compressum, elachanthus glaber and Eremophilia crassifolia in southwestern New South Wales

- Sluiter, Ian

Authors: Sluiter, Ian
Date: 2010
Type: Text , Journal article
Relation: Cunninghamia Vol. 11, no. (2010), p. 419-424
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Description: The arid and semi-arid southwest of New South Wales has received disproportionately less attention from botanists than other similar-sized geographic regions of the state. Recent work has extended our knowledge of three extremely rare plant taxa from this part of the state. Zygophyllum compressum (Zygophyllaceae) and Elachanthus glaber (Asteraceae) are restricted to gypseous rises within active saline groundwater discharge complexes with limited distribution in southwest New South Wales and occur within the plant community “Gypseous shrubland on rises and semi-arid plains” (ID253) which is listed as threatened (vulnerable) within the state. Eremophila crassifolia (Myoporaceae) is restricted to a few plants on a roadside and adjacent mallee vegetation approximately 35 km east of Wentworth. Based on IUCN criteria it is suggested that Eremophila crassifolia is critically endangered and Zygophyllum compressum and Elachanthus glaber endangered in New South Wales and all should be listed under the NSW Threatened Species Conservation Act 1995.
Description: C1

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Seasonal and interannual variations in diatom assemblages in Murray River connected wetlands in north-west Victoria, Australia

- Gell, Peter, Sluiter, Ian, Fluin, J.

Authors: Gell, Peter , Sluiter, Ian , Fluin, J.
Date: 2002
Type: Text , Journal article
Relation: Marine and Freshwater Research Vol. 53, no. 6 (2002), p. 981-992
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Description: Epipelic diatom assemblages collected from three wetlands connected to the Murray River displayed considerable variation in response to flooding and drying phases. Murray River water input usually generated diatom assemblages dominated by Aulacoseira species. After isolation, the diatom flora of two wetlands shifted to assemblages of small Fragilariaceae forms. Elevated nutrient levels corresponded with the appearance of eutraphentic taxa such as Cyclotella meneghiniana, Eolimna subminuscula, Luticola mutica and Nitzschia palea. Further evapoconcentration induced shifts to taxa tolerant of elevated salinity levels including Amphora coffeaeformis, Navicula incertata, Staurophora salina and Tryblionella hungarica. Ordination analyses reveal a strong chemical control on the diatom taxa present in the wetlands, in accordance with known ecological preferences for salinity and nutrients. The influence of nitrogen and phosphorus concentrations in controlling diatom assemblages was subordinate to salinity once conductivity values exceeded 1400 μS cm–1. The results of such biomonitoring provide a means of interpreting wetland history from fossil assemblages contained in sediment sequences.

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Soil reconstruction after mining fails to restore soil function in an Australian arid woodland

- Duncan, Corrine, Good, Megan, Sluiter, Ian, Cook, Simon, Schultz, Nick

Authors: Duncan, Corrine , Good, Megan , Sluiter, Ian , Cook, Simon , Schultz, Nick
Date: 2020
Type: Text , Journal article
Relation: Restoration Ecology Vol. 28, no. S1 (2020), p. A35-A43
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Description: The biogeochemical properties of soils drive ecosystem function and vegetation dynamics, and hence soil restoration after mining should aim to reinstate the soil properties and hydrological dynamics of remnant ecosystems. The aim of this study is to assess soil structure in two vegetation types in an arid ecosystem, and to understand how these soil properties compare to a reconstructed soil profile after mining. In an arid ecosystem in southeast Australia, soil samples were collected at five depths (to 105 cm) from remnant woodland and shrubland sites, and sites either disturbed or totally reconstructed after mining. We assessed soil physico-chemical properties and microbial activity. Soils in the remnant arid ecosystem had coarse-textured topsoils that overlay clay horizons, which allows water to infiltrate and avoid evaporation, but also slows drainage to deeper horizons. Conversely, reconstructed soils had high sand content at subsoil horizons and high bulk density and compaction at surface layers (0–20 cm). Reconstructed soils had topsoils with higher pH and electrical conductivity. The reconstructed soils did not show increased microbial activity with time since restoration. Overall, the reconstructed soil horizons were not organized in a way that allowed rainfall infiltration and water storage, as is imperative to arid-zone ecosystem function. Future restoration efforts in arid ecosystems should focus on increasing sand content of soils near the surface, to reduce evaporative water loss and improve soil quality and plant health. © 2020 Society for Ecological Restoration

Spinifex-mallee revegetation : Implications for restoration after mineral-sands mining in the Murray-Darling Basin

- Sluiter, Ian, Schweitzer, Andrew, Mac Nally, Ralph

Authors: Sluiter, Ian , Schweitzer, Andrew , Mac Nally, Ralph
Date: 2016
Type: Text , Journal article
Relation: Australian Journal of Botany Vol. 64, no. 6 (2016), p. 547-554
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Description: Mineral-sands mining in the semiarid and arid zone of south-eastern Australia is now a widespread disturbance that may adversely affect large areas of remnant vegetation, including mallee (Eucalyptus spp.) with hummock grass or spinifex (Triodia scariosa) understorey. No broad-scale restoration projects have been undertaken to revegetate mallee Eucalyptus species with spinifex. We report on the survivorship and relative importance (spatial coverage) of hand-planted tubestock 10 years after establishment in 2001, which included mallee Eucalyptus, Triodia scariosa, Acacia spp. and Hakea spp. These taxa are the dominant plants in a semiarid dune-swale system on a former mineral-sands mine licence area in semiarid, north-western Victoria. Mean survivorship of tubestock was 0.58±0.04. Spinifex (Triodia scariosa), needlewood (Hakea) and several mallee species (Eucalyptus spp.) survived substantially better than the average of all tubestock-planted species, although Acacia spp. had low survivorships. Although the plantings were undertaken in the early stages of the most severe drought in the instrumental record (the 'Millennium drought'), several taxa survived well and species such as spinifex established and developed ground coverage greater than the benchmark values for the ecological vegetation class of the location. We conclude that hand-planting of tubestock can achieve restoration objectives for this component of spinifex-mallee vegetation, even under extremely arduous conditions associated with long-term drought. We also herald the importance of taking a long-term view to the assessment of revegetation success, in this case 10 years. © CSIRO 2016.

Walnut rootstock selection for calcareous soils in Southeastern Australia and the potential for expanding the walnut industry in the region

- Sluiter, Ian, McKenzie, Lachie, Mitchell, Jeff

Authors: Sluiter, Ian , McKenzie, Lachie , Mitchell, Jeff
Date: 2014
Type: Text , Journal article
Relation: Acta Horticulturae Vol. 1050, no. (2014), p. 105-112
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Description: Persian walnuts are grown over relatively small area within irrigated settlements of the Murray Lowlands Province of Southeastern Australia compared with traditional crops such as grapes and citrus or emerging crops such as almonds. Poor walnut tree health usually associated with wrong rootstock selection, or growth in areas with inadequate topsoil depth, have inculcated a strong traditional resistance amongst growers and horticultural developers to walnuts as a viable alternative crop for the region. Recent trials comparing Juglans hindsii, a traditional rootstock for the area, with a new selection of Paradox rootstock, have shown the Paradox 'entity' significantly outperforms J. hindsii in terms of scion growth in the first year. The Paradox hybrid has also been shown to grow vigorously in soils with shallow topsoil depth above calcareous B horizon subsoils. This suitability of the Paradox hybrid to calcareous soils provides the potential to expand the walnut industry into parts of the Murray Lowland Province characterized by Calcarosol soils with as little as 30 cm topsoil.

Was the Oligocene-Miocene a time of fire and rain? Insights from brown coals of the southeastern Australia Gippsland Basin

- Holdgate, Guy, Wallace, Malcolm, Sluiter, Ian, Marcuccio, Daniel, Fromhold, Thomas, Wagstaff, Barbara

Authors: Holdgate, Guy , Wallace, Malcolm , Sluiter, Ian , Marcuccio, Daniel , Fromhold, Thomas , Wagstaff, Barbara
Date: 2014
Type: Text , Journal article
Relation: Palaeogeography Palaeoclimatology Palaeoecology Vol. 411, no. (2014), p. 65-78
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Description: Lithotype cycles (ranging from 10 to 30 m thick) in the brown coals of the Latrobe Valley, Gippsland Basin, Australia, display well-developed lightening-upward trends. Cycle tops are characterized by abrupt and unconformable boundaries with the overlying cycle. Geological, geochemical, palynological and macrofossil evidence is consistent with a relative drying (terrestrialization) upward depositional model for the cycles. The abundance of charcoal in dark lithotypes near the cycle bases is explained by the fire-prone and highly flammable nature of the herbaceous/reed wetlands, in common with similar modem wetlands in modem Australasia, in which the dark lithotypes are suggested to have formed. This, together with the greater preservation potential of charcoal in subaqueous environments, results in the wettest facies of the Latrobe Valley coals having the highest charcoal contents. Despite prevailing warm, wet climate conditions and the predominance of rainforests that are suggested to have characterized the Cenozoic of southern Australia, some swamp taxa were clearly already pre-adapted to tolerate fire and are likely to have been the ancestors of the fire-adapted floral communities of modem arid Australia. (c) 2014 Elsevier B.V. All rights reserved.

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