ORCID Profile
0000-0002-2020-6650
Current Organisation
University of Queensland
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Palaeoclimatology | Geochemistry | Organic Geochemistry | Palaeoecology | Palaeontology (incl. Palynology) | Evolutionary Impacts of Climate Change | Geology | Speciation and Extinction | Isotope Geochemistry
Ecosystem Adaptation to Climate Change | Effects of Climate Change and Variability on Australia (excl. Social Impacts) | Documentation of Undescribed Flora and Fauna | Understanding Australia's Past |
Publisher: Cambridge University Press (CUP)
Date: 2011
DOI: 10.1666/09067.1
Abstract: The rapid ecological expansion of grasses with C 4 photosynthesis at the end of the Neogene (8–2 Ma) is well documented in the fossil record of stable carbon isotopes. As one of the most profound vegetation changes to occur in recent geologic time, it paved the way for modern tropical grassland ecosystems. Changes in CO 2 levels, seasonality, aridity, herbivory, and fire regime have all been suggested as potential triggers for this broadly synchronous change, long after the evolutionary origin of the C 4 pathway in grasses. To date, these hypotheses have suffered from a lack of direct evidence for floral composition and structure during this important transition. This study aimed to remedy the problem by providing the first direct, relatively continuous record of vegetation change for the Great Plains of North America for the critical interval (ca. 12–2 Ma) using plant silica (phytolith) assemblages. Phytoliths were extracted from late Miocene-Pliocene paleosols in Nebraska and Kansas. Quantitative phytolith analysis of the 14 best-preserved assemblages indicates that habitats varied substantially in openness during the middle to late Miocene but became more uniformly open, corresponding to relatively open grassland or savanna, during the late Miocene and early Pliocene. Phytolith data also point to a marked increase of grass short cells typical of chloridoid and other potentially C 4 grasses of the PACMAD clade between 8 and 5 Ma these data suggest that the proportion of these grasses reached up to ∼50–60% of grasses, resulting in mixed C 3 -C 4 and highly heterogeneous grassland communities by 5.5 Ma. This scenario is consistent with interpretations of isotopic records from paleosol carbonates and ungulate tooth enamel. The rise in abundance of chloridoids, which were present in the central Great Plains since the early Miocene, demonstrates that the “globally” observed lag between C 4 grass evolution/taxonomic ersification and ecological expansion occurred at the regional scale. These patterns of vegetation alteration imply that environmental change during the late Miocene-Pliocene played a major role in the C 3 -C 4 shift in the Great Plains. Specifically, the importance of chloridoids as well as a decline in the relative abundance of forest indicator taxa, including palms, point to climatic drying as a key trigger for C 4 dominance.
Publisher: Wiley
Date: 05-2023
DOI: 10.1002/HYP.14878
Abstract: Oxygen (δ 18 O) and hydrogen (δ 2 H) isotope ratios, and their relationship to one another ( d ‐excess) are altered as water travels from the atmosphere to the land surface, into soils and plants and back to the atmosphere. Plants return water to the atmosphere through transpiration (evaporation through the stomata), which causes isotopic fractionation concentrating the heavier isotopes ( 18 O and 2 H) in the water that remains behind in the leaves. The degree of isotopic fractionation during transpiration is controlled largely by climate, and as a result can be predicted using process‐based models and climate data. The modelled transpirational isotopic fractionation can be applied to plant source water isotopic values to predict leaf water isotope ratios and generate maps of isotopic composition, or isoscapes. This approach of mechanistic modelling has been well demonstrated in the first generation of global leaf water isoscapes ( PLoS One , 3 (6), e2447, 2008). However, use of leaf water isoscapes in fields such as hydrology, ecology, and forensics requires a new generation of updated region‐specific isoscapes. Here, we generate leaf water isoscapes of δ 18 O, δ 2 H and d ‐excess for Australia, the driest vegetated continent on Earth, where leaf water represents a critical water resource for ecosystems. These isoscapes represent an improvement over previous global isoscapes due to their higher resolution, region‐specific, empirically derived plant parameters, and non‐equilibrium corrections for water vapour isotopic composition. The new isoscapes for leaf water are evaluated relative to observed isotope ratios of leaf cellulose and cherry juice. The model predictions for annual average leaf water isotope ratios showed strong correlations with these plant tissues that integrate over time. Moreover, inclusion of region‐specific leaf temperature estimates and non‐equilibirum vapour corrections improved prediction accuracy. Regionally based isoscapes provide improved characterisations of average leaf water isotope ratios needed to support research in hydrology, plant ecophysiology, atmospheric science, ecology, and geographic provenancing of biological materials.
Publisher: Elsevier BV
Date: 09-2009
Publisher: Annual Reviews
Date: 30-05-2012
DOI: 10.1146/ANNUREV-EARTH-042711-105535
Abstract: Hydrogen-isotopic abundances of lipid biomarkers are emerging as important proxies in the study of ancient environments and ecosystems. A decade ago, pioneering studies made use of new analytical methods and demonstrated that the hydrogen-isotopic composition of in idual lipids from aquatic and terrestrial organisms can be related to the composition of their growth (i.e., environmental) water. Subsequently, compound-specific deuterium/hydrogen (D/H) ratios of sedimentary biomarkers have been increasingly used as paleohydrological proxies over a range of geological timescales. Isotopic fractionation observed between hydrogen in environmental water and hydrogen in lipids, however, is sensitive to biochemical, physiological, and environmental influences on the composition of hydrogen available for biosynthesis in cells. Here we review the factors and processes that are known to influence the hydrogen-isotopic compositions of lipids—especially n-alkanes—from photosynthesizing organisms, and we provide a framework for interpreting their D/H ratios from ancient sediments and identify future research opportunities.
Publisher: Cambridge University Press (CUP)
Date: 2011
DOI: 10.1666/09068.1
Abstract: C 4 grasses form the foundation of warm-climate grasslands and savannas and provide important food crops such as corn, but their Neogene rise to dominance is still not fully understood. Carbon isotope ratios of tooth enamel, soil carbonate, carbonate cements, and plant lipids indicate a late Miocene-Pliocene (8–2 Ma) transition from C 3 vegetation to dominantly C 4 grasses at many sites around the world. However, these isotopic proxies cannot identify whether the C 4 grasses replaced woody vegetation (trees and shrubs) or C 3 grasses. Here we propose a method for reconstructing the carbon isotope ratio of Neogene grasses using the carbon isotope ratio of organic matter trapped in plant silica bodies (phytoliths). Although a wide range of plants produce phytoliths, we hypothesize that in grass-dominated ecosystems the majority of phytoliths will be derived from grasses, and will yield a grass carbon isotope signature. Phytolith extracts can be contaminated by non-phytolith silica (e.g., volcanic ash). To test the feasibility of the method given these potential problems, we examined s le purity (phytolith versus non-phytolith silica), abundance of grass versus non-grass phytoliths, and carbon isotope ratios of phytolith extracts from late Miocene-Pliocene paleosols of the central Great Plains. Isotope results from the purest s les are compared with phytolith assemblage analysis of these same extracts. The dual record spans the interval of focus (ca. 12–2 Ma), allowing us, for the first time, to investigate how isotopic shifts correlate with floral change. We found that many s les contained high abundances of non-biogenic silica therefore, only a small subset of “pure” s les ( % of phytoliths by volume) with good preservation were considered to provide reliable carbon isotope ratios. All phytolith assemblages contained high proportions (on average 85%) of grass phytoliths, supporting our hypothesis for grass-dominated communities. Therefore, the carbon isotope ratio of pure, well-preserved s les that are dominated by grass biosilica is considered a reliable measure of the proportion of C 3 and C 4 grasses in the Neogene. The carbon isotope ratios of the pure fossil phytolith s les indicate a transition from predominantly C 3 grasses to mixed C 3 -C 4 grasses by 5.5 Ma and then a shift to more than 80% C 4 grasses by 3–2 Ma. With the exception of the Pliocene s le, these isotopic data are broadly concordant with phytolith assemblages that show a general increase in C 4 grasses in the late Miocene. However, phytolith assemblage analysis indicates lower relative abundance of C 4 grasses in overall vegetation than do the carbon isotopes from the same phytolith assemblages. The discrepancy may relate to either (1) incomplete identification of (C 4 ) PACMAD phytoliths, (2) higher production of non-diagnostic phytoliths in C 4 grasses compared to C 3 grasses, or (3) biases in the isotope record toward grasses rather than overall vegetation. The impact of potential incomplete characterization of (C 4 ) PACMAD phytoliths on assemblage estimates of proportion of C 4 , though important, cannot reconcile discrepancies between the methods. We explore hypothesis (2) by analyzing a previously published data set of silica content in grasses and a small data set of modern grass leaf assemblage composition using analysis of variance, independent contrasts, and sign tests. These tests suggest that C 4 grasses do not have more silica than C 3 grasses there is also no difference with regard to production of non-diagnostic phytoliths. Thus, it is most likely that the discrepancy between phytolith assemblages and isotope ratios is a consequence of hypothesis (3), that the isotope signature is influenced by the contribution of non-diagnostic grass phytoliths, whereas the assemblage composition is not. Assemblage-based estimates of % C 4 within grasses, rather than overall vegetation, are in considerably better agreement with the isotope-based estimates. These results support the idea that, in grass-dominated assemblages, the phytolith carbon isotope method predominantly records shifts in dominant photosynthetic pathways among grasses, whereas phytolith assemblage analysis detects changes in overall vegetation. Carbon isotope ratios of fossil phytoliths in conjunction with phytolith assemblage analysis suggest that the late Neogene expansion of C 4 grasses was largely at the expense of C 3 grasses rather than C 3 shrubs/trees. Stable isotopic analysis of phytoliths can therefore provide unique information about grass community changes during the Neogene, as well as help test how grass phytolith morphology relates to photosynthetic pathway.
Publisher: Pensoft Publishers
Date: 28-07-2020
DOI: 10.3897/NEOBIOTA.59.53671
Abstract: The illegal pet trade facilitates the global dispersal of invasive alien species (IAS), providing opportunities for new pests to establish in novel recipient environments. Despite the increasing threat of IAS to the environment and economy, biosecurity efforts often lack suitable, scientifically-based methods to make effective management decisions, such as identifying an established IAS population from a single incursion event. We present a proof-of-concept for a new application of a stable isotope technique to identify wild and captive histories of an invasive pet species. Twelve red-eared slider turtles ( Trachemys scripta elegans ) from historic Australian incursions with putative wild, captive and unknown origins were analysed to: (1) present best-practice methods for stable isotope s ling of T. s. elegans incursions (2) effectively discriminate between wild and captive groups using stable isotope ratios and (3) present a framework to expand the methodology for use on other IAS species. A s ling method was developed to obtain carbon (δ 13 C) and nitrogen (δ 15 N) stable isotope ratios from the keratin layer of the carapace (shells), which are predominantly influenced by dietary material and trophic level respectively. Both δ 13 C and δ 15 N exhibited the potential to distinguish between the wild and captive origins of the s les. Power simulations demonstrated that isotope ratios were consistent across the carapace and a minimum of eight in iduals were required to effectively discriminate wild and captive groups, reducing overall s ling costs. Statistical classification effectively separated captive and wild groups by δ 15 N (captive: δ 15 N‰ ≥ 9.7‰, minimum of 96% accuracy). This study outlines a practical and accessible method for detecting IAS incursions, to potentially provide biosecurity staff and decision-makers with the tools to quickly identify and manage future IAS incursions.
Publisher: Elsevier BV
Date: 09-2013
Publisher: Elsevier BV
Date: 2011
Publisher: Elsevier BV
Date: 12-2020
Publisher: Wiley
Date: 11-04-2018
DOI: 10.1002/RCM.8085
Abstract: Purification of α-cellulose from plant tissues is commonly conducted to facilitate the reliable measurement of stable isotope ratios. Prior research has shown that different plant species and tissues react differently to standardised cellulose extraction techniques. Thus, no single method can be applied to all materials and careful consideration must be undertaken when selecting an extraction technique. In order to evaluate their suitability for use on Melaleuca quinquenervia leaves, a suite of eight different cellulose extraction techniques were tested. Leaves of this species are preserved in perched lakes on southeast Queensland's sand islands and are a focus of ongoing palaeoclimate research. Elemental analyser/isotope ratio mass spectrometry was used to measure stable carbon and oxygen isotopic ratios and s le composition was measured using Fourier transform infrared spectroscopy. We demonstrate that the standard Brendel extraction technique, particularly with a higher reagent volume and longer boiling time, produces cellulose with the lowest spread in isotopic ratios among replicates, and with the fewest impurities detected by Fourier transform infrared spectroscopy. We also show that pre-treating the leaves to extract leaf wax lipids in order to enable paired analysis from the same sub-fossil leaves does not significantly affect the quality of the isotopic results. The standard Brendel method allows the most precise stable carbon and oxygen information to be retrieved from the leaves of M. quinquenervia. This unlocks the potential to study palaeoclimate proxy records from our study site and potentially throughout the natural range of the species across eastern Australia, Papua New Guinea and New Caledonia.
Publisher: Elsevier BV
Date: 07-2018
Publisher: Copernicus GmbH
Date: 05-11-2013
Abstract: Abstract. During the summer of 2011, the Bighorn Basin Coring Project (BBCP) recovered over 900 m of overlapping core from 3 different sites in late Paleocene to early Eocene fluvial deposits of northwestern Wyoming. BBCP cores are being used to develop high-resolution proxy records of the Paleocene–Eocene Thermal Maximum (PETM) and Eocene Thermal Maximum 2 (ETM2) hyperthermal events. These events are short-term, large magnitude global warming events associated with extreme perturbations to the earth's carbon cycle. Although the PETM and ETM2 occurred ~55–52 million years ago, they are analogous in many ways to modern anthropogenic changes to the carbon cycle. By applying various sedimentological, geochemical, and palynological methods to the cores, we hope to better understand what caused these events, study the biogeochemical and ecological feedbacks that operated during them, and reveal precisely how they impacted continental environments. Core recovery was % in all holes and most drilling was carried out without fluid additives, showing that continuous coring of continental smectitic deposits like these can be achieved with minimal risk of contamination to molecular biomarkers. Cores were processed in the Bremen Core Repository where the science team convened for 17 days to carry out data collection and s ling protocols similar to IODP projects. Initial results show that the weathered horizon extends to as much as ~30 m below the surface and variations in magnetic susceptibility within the cores record an interplay between grain size and pedogenesis. Previous investigations of outcrops near the BBCP drill sites allow detailed evaluation of the effects of weathering on common proxy methods. Studies of lithofacies, organic geochemistry, stable isotope geochemistry, calibrated XRF core scanning, paleomagnetics, and palynology are underway and will represent the highest resolution and most integrated proxy records of the PETM from a continental setting yet known. An extensive outreach program is in place to capitalize on the educational value associated with the Bighorn Basin's unusually complete record of Phanerozoic earth history.
Publisher: Elsevier BV
Date: 07-2021
Publisher: Springer Science and Business Media LLC
Date: 13-04-2022
DOI: 10.1007/S12520-022-01540-3
Abstract: We review palaeoenvironmental applications of stable isotope analysis to Late Pleistocene archaeological sites across Southeast Asia (SEA), a region critical to understanding the evolution of Homo sapiens and other co-existing Late Pleistocene (124–11.7 ka) hominins. Stable isotope techniques applied to archaeological deposits offer the potential to develop robust palaeoenvironmental reconstructions, to contextualise the occupational and non-occupational history of a site. By evaluating the published research in this field, we show that sediments, guano, tooth enamel, speleothem and biomolecular material such as leaf waxes have great potential to provide site-specific palaeoenvironmental records and local and catchment-scale landscape context to hominin dispersal in the region. However, stable isotope techniques used in these contexts are in their infancy in SEA, and the diagenetic controls associated with hot and humid environments that typify the region are not yet fully understood. Additionally, availability of sources of stable isotopes varies between sites. Nonetheless, even the limited research currently available shows that stable isotope analyses can aid in developing a better understanding of the role of the environment on the nature and timing of dispersals of our species eastwards into SEA and beyond.
Publisher: Geological Society of America
Date: 20-04-2016
DOI: 10.1130/B31389.1
Publisher: American Geophysical Union (AGU)
Date: 17-01-2021
DOI: 10.1029/2020GL090964
Abstract: C 4 grasslands proliferated later in Australia than they did on other continents (∼3.5 Ma vs. 10–5 Ma). It remains unclear whether this delay reflects differences in climate conditions or ecological feedbacks, such as fire, that promote C 4 ecosystems. Here, we evaluated these factors using terrestrial biomarkers from marine sediments off western Australia. Fire‐derived polycyclic aromatic hydrocarbons (PAH) indicate fire ecology did not substantially change during or following C 4 expansion. The presence of fire‐adapted C 3 woody vegetation likely diminished the role of fire and delayed C 4 expansion until it was prompted by climate drying between 3.5 and 3.0 Ma. At the same time, mass accumulation rates of weathered PAHs increased 100‐fold, which indicates a significant loss of soil carbon accompanied this ecosystem shift. The tight couplings between hydroclimate and carbon storage altered boundary conditions for Australian ecosystems, and similar abrupt behavior may shape environmental responses to climate change.
Publisher: Elsevier BV
Date: 03-2006
Publisher: Elsevier BV
Date: 2013
Publisher: Wiley
Date: 08-2020
DOI: 10.1002/AJB2.1523
Publisher: Wiley
Date: 11-12-2018
DOI: 10.1111/DDI.12858
Publisher: Elsevier BV
Date: 02-2020
Publisher: Elsevier BV
Date: 2017
Publisher: Wiley
Date: 24-04-2020
DOI: 10.1111/NPH.16558
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/BT20036
Abstract: The drivers and rate of vegetation change across spatial gradients can give critical insights into the compositional and structural change we can expect under climate change. Spatial ecotones are of particular interest as they represent heterogeneity in the patterning of vegetation that may reflect how temporal environmental change will manifest in more abrupt step changes in plant composition and/or structure. Another dimension of interest is the degree to which survey methodology impacts the detectability of thresholds in vegetation. We surveyed a Mediterranean to arid zone gradient in South Australia with nested and non-nested transect designs and related the observed vegetation change to soil, landscape and climate to determine the strongest environmental associations. Ordination, principal components analysis (PCA) and threshold indicator taxa analysis (TITAN) were used to detect potential ecotones associated with environmental thresholds. Results from the two transects were compared with test the effects of survey method and spatial s ling on pattern detection. Ordinations and regressions for both transects indicated vegetation changed linearly along the environmental gradient. Species richness and total cover increased with rainfall. Species turnover was very high, with low nestedness, indicating high susceptibility to environmental change. Climate is the major driver of broad-scale vegetation change on our gradient and at this scale vegetation trends are detectable with a range of survey methodologies. TITAN identification of a threshold within the shorter, nested transect (but not the longer transect which extended into the arid zone) indicated that survey methodology influences ecotone detectability, and that although smaller-scale vegetation disjunctions may be present, change spanning the entire mesic to arid zone is largely monotonic.
Publisher: Wiley
Date: 23-03-2016
DOI: 10.1111/PCE.12703
Abstract: Leaf water contains naturally occurring stable isotopes of oxygen and hydrogen in abundances that vary spatially and temporally. When sufficiently understood, these can be harnessed for a wide range of applications. Here, we review the current state of knowledge of stable isotope enrichment of leaf water, and its relevance for isotopic signals incorporated into plant organic matter and atmospheric gases. Models describing evaporative enrichment of leaf water have become increasingly complex over time, reflecting enhanced spatial and temporal resolution. We recommend that practitioners choose a model with a level of complexity suited to their application, and provide guidance. At the same time, there exists some lingering uncertainty about the biophysical processes relevant to patterns of isotopic enrichment in leaf water. An important goal for future research is to link observed variations in isotopic composition to specific anatomical and physiological features of leaves that reflect differences in hydraulic design. New measurement techniques are developing rapidly, enabling determinations of both transpired and leaf water δ(18) O and δ(2) H to be made more easily and at higher temporal resolution than previously possible. We expect these technological advances to spur new developments in our understanding of patterns of stable isotope fractionation in leaf water.
Publisher: Public Library of Science (PLoS)
Date: 22-08-2022
DOI: 10.1371/JOURNAL.PONE.0271603
Abstract: Numerous studies have analysed the relationship between C 4 plant cover and climate. However, few have examined how different C 4 taxa vary in their response to climate, or how environmental factors alter C 4 :C 3 abundance. Here we investigate (a) how proportional C 4 plant cover and richness (relative to C 3 ) responds to changes in climate and local environmental factors, and (b) if this response is consistent among families. Proportional cover and richness of C 4 species were determined at 541 one-hectare plots across Australia for 14 families. C 4 cover and richness of the most common and abundant families were regressed against climate and local parameters. C 4 richness and cover in the monocot families Poaceae and Cyperaceae increased with latitude and were strongly positively correlated with January temperatures, however C 4 Cyperaceae occupied a more restricted temperature range. Seasonal rainfall, soil pH, soil texture, and tree cover modified proportional C 4 cover in both families. Eudicot families displayed considerable variation in C 4 distribution patterns. Proportional C 4 Euphorbiaceae richness and cover were negatively correlated with increased moisture availability (i.e. high rainfall and low aridity), indicating they were more common in dry environments. Proportional C 4 Chenopodiaceae richness and cover were weakly correlated with climate and local environmental factors, including soil texture. However, the explanatory power of C 4 Chenopodiaceae models were poor, suggesting none of the factors considered in this study strongly influenced Chenopodiaceae distribution. Proportional C 4 richness and cover in Aizoaceae, Amaranthaceae, and Portulacaceae increased with latitude, suggesting C 4 cover and richness in these families increased with temperature and summer rainfall, but s le size was insufficient for regression analysis. Results demonstrate the unique relationships between different C 4 taxa and climate, and the significant modifying effects of environmental factors on C 4 distribution. Our work also revealed C 4 families will not exhibit similar responses to local perturbations or climate.
Publisher: Wiley
Date: 07-2012
DOI: 10.3732/AJB.1100525
Abstract: Leaf venation is linked to physiological performance, playing a critical role in ecosystem function. Despite the importance of leaf venation, associated bundle sheath extensions (BSEs) remain largely unstudied. Here, we quantify plasticity in the spacing of BSEs over irradiance and precipitation gradients. Because physiological function(s) of BSEs remain uncertain, we additionally explored a link between BSEs and water use efficiency (WUE). We s led leaves of heterobaric trees along intracrown irradiance gradients in natural environments and growth chambers and correlated BSE spacing to incident irradiance. Additionally, we s led leaves along a precipitation gradient and correlated BSE spacing to precipitation and bulk δ(13)C, a proxy for intrinsic WUE. BSE spacing was quantified using a novel semiautomatic method on fresh leaf tissue. With increased irradiance or decreased precipitation, Liquidambar styraciflua decreased BSE spacing, while Acer saccharum showed little variation in BSE spacing. Two additional species, Quercus robur and Platanus occidentalis, decreased BSE spacing with increased irradiance in growth chambers. BSE spacing correlated with bulk δ(13)C, a proxy for WUE in L. styraciflua, Q. robur, and P. occidentalis leaves but not in leaves of A. saccharum. We demonstrated that BSE spacing is plastic with respect to irradiance or precipitation and independent from veins, indicating BSE involvement in leaf adaptation to a microenvironment. Plasticity in BSE spacing was correlated with WUE only in some species, not supporting a function in water relations. We discuss a possible link between BSE plasticity and life history, particularly canopy position.
Publisher: American Geophysical Union (AGU)
Date: 10-2013
DOI: 10.1002/GGGE.20265
Publisher: Springer Science and Business Media LLC
Date: 04-2021
DOI: 10.1038/S41597-021-00877-Z
Abstract: The photosynthetic pathway of plants is a fundamental trait that influences terrestrial environments from the local to global level. The distribution of different photosynthetic pathways in Australia is expected to undergo a substantial shift due to climate change and rising atmospheric CO 2 however, tracking change is hindered by a lack of data on the pathways of species, as well as their distribution and relative cover within plant communities. Here we present the photosynthetic pathways for 2428 species recorded across 541 plots surveyed by Australia’s Terrestrial Ecosystem Research Network (TERN) between 2011 and 2017. This dataset was created to facilitate research exploring trends in vegetation change across Australia. Species were assigned a photosynthetic pathway using published literature and stable carbon isotope analysis of bulk tissue. The photosynthetic pathway of species can be extracted from the dataset in idually, or used in conjunction with vegetation surveys to study the occurrence and abundance of pathways across the continent. This dataset will be updated as TERN’s plot network expands and new information becomes available.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 11-11-2005
Abstract: Rapid global warming of 5° to 10°C during the Paleocene-Eocene Thermal Maximum (PETM) coincided with major turnover in vertebrate faunas, but previous studies have found little floral change. Plant fossils discovered in Wyoming, United States, show that PETM floras were a mixture of native and migrant lineages and that plant range shifts were large and rapid (occurring within 10,000 years). Floral composition and leaf shape and size suggest that climate warmed by ∼5°C during the PETM and that precipitation was low early in the event and increased later. Floral response to warming and/or increased atmospheric CO 2 during the PETM was comparable in rate and magnitude to that seen in postglacial floras and to the predicted effects of anthropogenic carbon release and climate change on future vegetation.
Publisher: Wiley
Date: 18-12-2022
DOI: 10.1002/PPP3.10349
Abstract: Sandalwood and other high value tree species are under significant threat from illegal harvest. Illegal logging is an increasing problem contributing to deforestation, bio ersity loss, human rights abuses and funding transnational crime. Successful prosecution of illegal logging is hindered by a lack of methods to provide evidence of the origin of timber. New analytical techniques have been developed to trace timber back to its source. These methods, together with the establishment of sustainable sources of forest resources, can help protect vulnerable species by providing evidence to prosecute illegal harvest and ensure that commercially available forest products come from sustainable sources. Sandalwood is highly valued for its fragrant oil and has a long history of cultural and economic importance in many regions of the world. Historical overharvest and poor management have depleted natural populations of sandalwood, which are slow to regenerate. The increasing establishment of plantation sandalwood creates an alternative resource for the sandalwood industry while potentially relieving harvesting pressure on natural stands. Due to the high demand for sandalwood, remaining wild populations are still under threat from illegal logging and methods to identify the source of harvested sandalwood are needed. Laws and regulations aimed at preventing illegal harvest and possession of sandalwood have been put in place but cannot be enforced without the forensic tools to independently verify claimed origin or product quality. The high value of sandalwood combined with the difficulties in enforcing illegal logging laws makes these species particularly vulnerable to poaching. There is an immediate need to develop tools that can identify illegally sourced and adulterated sandalwood products. This paper reviews the current and developing scientific tools that can help identify and control illegal activity in sandalwood supply chains and provides recommendations for future research. Topics include isotope and DNA analysis for tracing illegally harvested sandalwood, chemical profiling for quality control of sandalwood oils, network and policy development to establish a framework for future regulation of the sandalwood trade.
Publisher: Elsevier BV
Date: 06-2019
Publisher: Elsevier BV
Date: 02-2015
Publisher: Wiley
Date: 19-04-2016
DOI: 10.1111/GCB.13277
Abstract: Quantitative reconstructions of terrestrial climate are highly sought after but rare, particularly in Australia. Carbon isotope discrimination in plant leaves (Δleaf ) is an established indicator of past hydroclimate because the fractionation of carbon isotopes during photosynthesis is strongly influenced by water stress. Leaves of the evergreen tree Melaleuca quinquenervia have been recovered from the sediments of some perched lakes on North Stradbroke and Fraser Islands, south-east Queensland, eastern Australia. Here, we examine the potential for using M. quinquenervia ∆leaf as a tracer of past rainfall by analysing carbon isotope ratios (δ(13) C) of modern leaves. We firstly assess Δleaf variation at the leaf and stand scale and find no systematic pattern within leaves or between leaves due to their position on the tree. We then examine the relationships between climate and Δleaf for a 11-year time series of leaves collected in a litter tray. M. quinquenervia retains its leaves for 1-4 years thus, cumulative average climate data are used. There is a significant relationship between annual mean ∆leaf and mean annual rainfall of the hydrological year for 1-4 years (i.e. 365-1460 days) prior to leaf fall (r(2) = 0.64, P = 0.003, n = 11). This relationship is marginally improved by accounting for the effect of pCO2 on discrimination (r(2) = 0.67, P = 0.002, n = 11). The correlation between rainfall and Δleaf , and the natural distribution of Melaleuca quinquenervia around wetlands of eastern Australia, Papua New Guinea and New Caledonia offers significant potential to infer past rainfall on a wide range of spatial and temporal scales.
Publisher: Elsevier BV
Date: 15-10-2007
Publisher: American Geophysical Union (AGU)
Date: 17-05-2018
DOI: 10.1029/2018GL077833
Publisher: Elsevier BV
Date: 04-2019
Publisher: American Geophysical Union (AGU)
Date: 05-2019
DOI: 10.1029/2019PA003579
Publisher: Springer Science and Business Media LLC
Date: 05-07-2022
DOI: 10.1007/S10980-022-01476-Y
Abstract: Maps of C 3 and C 4 plant abundance and stable carbon isotope values (δ 13 C) across terrestrial landscapes are valuable tools in ecology to investigate species distribution and carbon exchange. Australia has a predominance of C 4 -plants, thus monitoring change in C 3 :C 4 cover and δ 13 C is essential to national management priorities. We applied a novel combination of field surveys and remote sensing data to create maps of C 3 and C 4 abundance in Australia, and a vegetation δ 13 C isoscape for the continent. We used vegetation and land-use rasters to categorize grid-cells (1 ha) into woody (C 3 ), native herbaceous, and herbaceous cropland (C 3 and C 4 ) cover. Field surveys and environmental factors were regressed to predict native C 4 herbaceous cover. These layers were combined and a δ 13 C mixing model was used to calculate site-averaged δ 13 C values. Seasonal rainfall, maximum summer temperature, and soil pH were the best predictors of C 4 herbaceous cover. Comparisons between predicted and observed values at field sites indicated our approach reliably predicted generalised C 3 :C 4 abundance. Southern Australia, which has cooler temperatures and winter rainfall, was dominated by C 3 vegetation and low δ 13 C values. C 4 -dominated areas included northern savannahs and grasslands. Our isoscape approach is distinct because it incorporates remote sensing products that calculate cover beneath the canopy, the influence of local factors, and extensive validation, all of which are critical to accurate predictions. Our models can be used to predict C 3 :C 4 abundance under climate change, which is expected to substantially alter current C 3 :C 4 abundance patterns.
Publisher: Elsevier BV
Date: 05-2004
Publisher: Oxford University Press (OUP)
Date: 05-2018
Publisher: Wiley
Date: 19-05-2017
DOI: 10.1002/ECE3.2995
Publisher: Elsevier BV
Date: 11-2017
Start Date: 2013
End Date: 2015
Funder: Australian Research Council
View Funded ActivityStart Date: 2011
End Date: 2015
Funder: Australian Research Council
View Funded ActivityStart Date: 2021
End Date: 2024
Funder: Australian Research Council
View Funded ActivityStart Date: 08-2022
End Date: 08-2025
Amount: $476,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 09-2012
End Date: 08-2018
Amount: $714,418.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2013
End Date: 12-2016
Amount: $230,000.00
Funder: Australian Research Council
View Funded Activity