Australian Ecosystems Research Articles

Comparative chemical sensitivity between marine Australian and Northern Hemisphere ecosystems: Is an uncertainty factor warranted for water‐quality–guideline setting?

The lack of Australian species data has pragmatically led to the use of toxicological data from the Northern Hemisphere to develop water-quality guidelines. However, it is unknown whether Australian species and ecosystems are equally as sensitive and if an uncertainty factor is warranted for Australian guideline setting. In the present study, it is hypothesized that an uncertainty factor is not required. This was tested by generating species sensitivity distributions by 2 parametric methods using marine Northern Hemisphere and Australian/New Zealand data. Sufficient acute data were found for only 3 compounds: 4-chlorophenol, phenol, and ammonia. For ammonia and 4-chlorophenol, the 95% species protection levels generated with Australian and Northern Hemisphere data were essentially the same. For phenol, protection levels derived from Australian data were approximately 10-fold higher. Therefore, the derived benchmark concentration from Northern Hemisphere data should be protective. It is tentatively concluded that there is no need for an uncertainty factor when deriving water-quality guidelines for marine Australian ecosystems using Northern Hemisphere data. It is, however, noted that this is based on only 3 compounds.

The Ecology of Feral Cats in Mesic, Australian Ecosystems (Abstract)

The body of literature on feral cat (Felis silvestris catus) ecology in the arid- and semi-arid areas of Australia is increasing, but less is known about feral cats in mesic environments. Inherent differences between these habitat types, notably habitat complexity, are likely to be affect¬ing the responses of cats to potential competitors and predators. This research seeks to address this dearth of information by investigating the ecology of cats in the mesic agri-ecosystems of north-east New South Wales, Australia. Camera traps will be used to conduct a capture-recapture study of feral cats to estimate cat density based on pelage pattern and morphology, and GPS collars will log information on cat movement. A particular focus of our work is to tease out inter¬actions between feral cats and the endangered native carnivore, the spotted-tailed quoll (Dasyurus maculatus), to shed light on how these similarly-sized mesopredators coexist. Here we will present preliminary data on spatial and temporal use of the habitats by cats in complex habitats, and present hypotheses, based on the current body of predator interaction literature, that will be tested in the coming years.

High fidelity simulation using the updated distributed interactive simulation standard

Distributed interactive simulation (DIS) is a widely-used networking protocol standard that provides a method of communicating entity information among simulators and simulations to create a synthetic environment. The IEEE DIS standard is being revised with balloting expected to be completed in 2012. The proposed new standard includes an extensive revision, clearing up ambiguities present in the existing 1998 version, and adding additional capabilities that reflect changes in military equipment and doctrine, and also advances in technology such as the internet, mobile telephony, and the widespread use of the global positioning system for positional and time data. Five new protocol data units have been added to include information operations capability, enhanced warfare support, and the ability to communicate information about individual attributes for a particular entity, object, or event. In this paper we review these new capabilities in detail, and explore what this will mean for the Australian simulation ecosystem.

Holocene vertebrate fossils aid the management and restoration of Australian ecosystems

SummaryEuropean‐settlement‐related impacts over the past 200 years pose many challenges for the conservation and restoration of Australia's ecosystems. Landscape modification, associated habitat loss and the introduction of exotic species have caused the extinction and mainland extirpation of numerous vertebrates. This process happened so quickly that many species became locally or functionally extinct before their presence was documented. A growing body of research on Holocene fossil accumulations is providing insights into the composition and biogeography of Australian ecosystems prior to European settlement. This review explores the similarities between palaeo‐ and neo‐ecology and how Holocene (last 10,000 years) assemblages can be used by neo‐ecologists, conservation managers and policy makers to identify and fill gaps in knowledge and contribute to the management and restoration of Australia's degraded ecosystems.

Continental‐Scale Governance and the Hastening of Loss of Australia's Biodiversity

Against a global backdrop of rapid environmental change, conserving biodiversity poses one of the biggest and most important challenges to society. For this reason, systems of nature reserves have never been more important. Protected areas are under threat in many parts of the world (Mascia & Pailler 2011), but the weakening of protected areas in a rich, developed country with a global reputation for conservation leadership (Harrison 2006) is particularly alarming (Ritchie 2013). Consequently, we are concerned about the recent spate of substantial policy, legislative, and management changes being made by three of six Australian state governments for exploitative uses of national parks—actions that could affect much of Australia and have negative effects on biodiversity.

Eucalypts face increasing climate stress

Global climate change is already impacting species and ecosystems across the planet. Trees, although long-lived, are sensitive to changes in climate, including climate extremes. Shifts in tree species' distributions will influence biodiversity and ecosystem function at scales ranging from local to landscape; dry and hot regions will be especially vulnerable. The Australian continent has been especially susceptible to climate change with extreme heat waves, droughts, and flooding in recent years, and this climate trajectory is expected to continue. We sought to understand how climate change may impact Australian ecosystems by modeling distributional changes in eucalypt species, which dominate or codominate most forested ecosystems across Australia. We modeled a representative sample of Eucalyptus and Corymbia species (n = 108, or 14% of all species) using newly available Representative Concentration Pathway (RCP) scenarios developed for the 5th Assessment Report of the IPCC, and bioclimatic and substrate predictor variables. We compared current, 2025, 2055, and 2085 distributions. Overall, Eucalyptus and Corymbia species in the central desert and open woodland regions will be the most affected, losing 20% of their climate space under the mid-range climate scenario and twice that under the extreme scenario. The least affected species, in eastern Australia, are likely to lose 10% of their climate space under the mid-range climate scenario and twice that under the extreme scenario. Range shifts will be lateral as well as polewards, and these east–west transitions will be more significant, reflecting the strong influence of precipitation rather than temperature changes in subtropical and midlatitudes. These net losses, and the direction of shifts and contractions in range, suggest that many species in the eastern and southern seaboards will be pushed toward the continental limit and that large tracts of currently treed landscapes, especially in the continental interior, will change dramatically in terms of species composition and ecosystem structure.

Steroid oestrogens in the environment: an Australian perspective

Endocrine disrupting compounds (EDCs) have been in the scientific spotlight since the 1980s. However, there has been much less research reported in Australia than in other developed countries and little information is known about how these compounds interact with native Australian species compared to European and North American fauna. This is of concern because Australia has distinct wildlife and environments that face increasing intensity and frequency of extreme, climatic events compared to northern hemisphere countries. Since oestrogenic compounds cannot be prevented from entering wastewater their management and removal must occur at wastewater treatment plants. Biological treatment is the most effective tool in this regard; however the financial and environmental costs must be balanced with the environmental benefit to effectively plan treatment options. Since standard risk assessment models and procedures developed internationally are unlikely to translate well to Australian ecosystems, new, novel and localised research on both the monitoring and assessment of EDCs in Australian wastewater and receiving aquatic environments is recommended. This includes the development of relevant bioassays and application of treatment technologies that reflect the local community and climate.

Biomass estimation within an Australian eucalypt forest: Meso-scale spatial arrangement and the influence of sampling intensity

Plant biomass is important when measuring productivity, calculating carbon stores and when studying interactions between abiotic factors and biotic organisms. However, information on the spatial arrangement of above ground live biomass (AGLB) is lacking and while the influence of replication on estimated AGLB has been studied, it has rarely been the focus in Australian ecosystems. This study examined spatial arrangement of AGLB, the influence of survey design, and interactions between abiotic factors and AGLB. Above ground live biomass was measured in a remnant eucalypt forest at Karawatha Forest Park (∼900ha), a long term ecological research site (LTER node) within the Terrestrial Ecosystem Research Network (TERN) South-east Queensland Peri-urban Supersite, Australia. Sampling of woody vegetation occurred in 32 one-hectare plots systematically placed at 500m intervals. Above ground live biomass was estimated to be 146.51Mg ha−1, with spatial interpolation calculating that there was 133,487Mg of AGLB (>1cm DBH) within Karawatha Forest Park. Time and effort could be saved by not measuring trees <10cm, because only ∼7% of the AGLB biomass (>1cm) would be lost. Despite relatively low variation in AGLB among plots, bootstrapping indicated that at least 15 PPBio (Program for Planned Biodiversity and Ecosystem Research) plots are needed to precisely estimate AGLB within Karawatha Forest Park. Topography and soil chemistry performed poorly at explaining AGLB, and it is likely that past and present human activities (e.g. logging and arson) play a role in influencing AGLB at Karawatha Forest Park. This study identifies the importance of independent replication to capture variation in AGLB for carbon storage estimation, and the power of systematic sampling within sites for mapping carbon stocks at meso and larger scales.

N biogeochemistry and cycling in two well-drained savannas: a comparison between the Orinoco Basin (Llanos, Venezuela) and Ivory Coast (western Africa)

When a savanna burns, a decline in the input of organic matter and nutrients to the soil occurs. However, the existence of recurrent fires is a natural condition and N depletion by fire is not incompatible with the existence of savannas per se. Consequently, savanna vegetations have evolved under fires, implying a near to steady-state N budget. In some Australian and African ecosystems, N fixation appears to be insufficient to replace losses inducing soil-N depletion, whereas in neotropical Llanos and western African savannas, the N-fixation and precipitation seem to be enough to maintain production despite fires. This review presents information about well-drained savannas, namely Trachypogon savannas in Orinoco Llanos and Andropogonae savannas in Ivory Coast. The sites present similarities in climate and fire regime differing in soil parent material. A report on N budgets is presented. The budget was positive, since losses seem to be balanced by inputs in rainfall and biological fixation. Uncertainties in flux measures indicate that more work on those aspects are required. Results indicate that the estimated amounts of dinitrogen fixation and deposition seem to be enough to maintain plant production. Data support the hypothesis that the vegetation in the natural savanna has evolved under fire constraint.

Ecology and Behaviour of Burton&amp;rsquo;s Legless Lizard (Lialis burtonis, Pygopodidae) in Tropical Australia

The elongate, functionally limbless flap-footed lizards (family Pygopodidae) are found throughout Australia, ranging into southern New Guinea. Despite their diversity and abundance in most Australian ecosystems, pygopodids have attracted little scientific study. An intensive ecological study of one pygopodid, Burton's legless lizard (Lialis burtonis Gray 1835), was conducted in Australia's tropical Northern Territory. L. burtonis eats nothing but other lizards, primarily skinks, and appears to feed relatively infrequently (only 20.8% of stomachs contained prey). Ovulation and mating occur chiefly in the late dry-season (beginning around September), and most egg-laying takes place in the early to middle wet-season (November-January). Females can lay multiple clutches per year, some of which may be fertilised with stored sperm. Free-ranging L. burtonis are sedentary ambush foragers, with radio-tracked lizards moving on average < 5 m/day. Most foraging is done diurnally, but lizards may be active at any time of day or night. Radiotracked lizards were usually found in leaf-litter microhabitats, a preference that was also evident in habitat-choice experiments using field enclosures. Lizards typically buried themselves in 6-8 cm of litter; at this depth, they detect potential prey items while staying hidden from predators and prey and avoiding lethally high temperatures.

Contrasting fire responses to climate and management: insights from two Australian ecosystems

This study explores effects of climate change and fuel management on unplanned fire activity in ecosystems representing contrasting extremes of the moisture availability spectrum (mesic and arid). Simulation modelling examined unplanned fire activity (fire incidence and area burned, and the area burned by large fires) for alternate climate scenarios and prescribed burning levels in: (i) a cool, moist temperate forest and wet moorland ecosystem in south-west Tasmania (mesic); and (ii) a spinifex and mulga ecosystem in central Australia (arid). Contemporary fire activity in these case study systems is limited, respectively, by fuel availability and fuel amount. For future climates, unplanned fire incidence and area burned increased in the mesic landscape, but decreased in the arid landscape in accordance with predictions based on these limiting factors. Area burned by large fires (greater than the 95th percentile of historical, unplanned fire size) increased with future climates in the mesic landscape. Simulated prescribed burning was more effective in reducing unplanned fire activity in the mesic landscape. However, the inhibitory effects of prescribed burning are predicted to be outweighed by climate change in the mesic landscape, whereas in the arid landscape prescribed burning reinforced a predicted decline in fire under climate change. The potentially contrasting direction of future changes to fire will have fundamentally different consequences for biodiversity in these contrasting ecosystems, and these will need to be accommodated through contrasting, innovative management solutions.

Herds Overhead: Nimbadon lavarackorum (Diprotodontidae), Heavyweight Marsupial Herbivores in the Miocene Forests of Australia

The marsupial family Diprotodontidae (Diprotodontia, Vombatiformes) is a group of extinct large-bodied (60–2500 kg) wombat-like herbivores that were common and geographically widespread in Cenozoic fossil deposits of Australia and New Guinea. Typically they are regarded to be gregarious, terrestrial quadrupeds and have been likened in body form among placental groups to sheep, rhinoceros and hippopotami. Arguably, one of the best represented species is the zygomaturine diprotodontid Nimbadon lavarackorum which is known from exceptionally well-preserved cranial and postcranial material from the middle Miocene cave deposit AL90, in the Riversleigh World Heritage Area, northwestern Queensland. Here we describe and functionally analyse the appendicular skeleton of Nimbadon lavarackorum and reveal a far more unique lifestyle for this plesiomorphic and smallest of diprotodontids. Striking similarities are evident between the skeleton of Nimbadon and that of the extant arboreal koala Phascolarctos cinereus, including the powerfully built forelimbs, highly mobile shoulder and elbow joints, proportionately large manus and pes (both with a semi-opposable digit I) and exceedingly large, recurved and laterally compressed claws. Combined with the unique (among australidelphians) proportionately shortened hindlimbs of Nimbadon, these features suggest adept climbing ability, probable suspensory behaviour, and an arboreal lifestyle. At approximately 70 kg, Nimbadon is the largest herbivorous mammal to have occupied the forest canopies of Australia - an ecological niche that is no longer occupied in any Australian ecosystem and one that further expands the already significant niche diversity displayed by marsupials during the Cenozoic.

Cautionary considerations for positive dingo management: a response to the Johnson and Ritchie critique of Fleming et al. (2012)

Johnson and Ritchie (2012) have provided a criticism of our opinion piece (Fleming et al. 2012). There is some common ground, but we remain unconvinced by their view that our reasoning was unsound or beside the point. In this response, we discuss where Johnson and Ritchie have provided unconvincing evidence to refute our seven considerations, and reiterate and demonstrate why these considerations remain important. The mesopredator release or suppression hypothesis in Australian ecosystems must be objectively evaluated before positive management of dingoes and other free-ranging dogs is recommended or implemented. Adaptive comanagement of free-ranging dogs can be used for both biodiversity conservation and the mitigation of livestock predation but caution must be exercised when considering using free-ranging dogs as a conservation tool.

Bunnies, Bilbies, and the Ethic of Ecological Remembrance

Bunnies, Bilbies, and the Ethic of Ecological Remembrance

The Seedling Ratio Method for determining ungulate impacts on forest understoreys: Utility in an Australian ecosystem

SummaryThe Seedling Ratio Method was devised to assess the impacts of introduced ungulates on plant species richness in forest understoreys. The method has successfully assessed ungulate impacts on species richness in forests in New Zealand and Hawaii, which do not have native herbivores. We tested the three critical assumptions that underlie this method to investigate its potential for use in an Australian ecosystem. This study was conducted in the Yarra Ranges National Park (YRNP), Victoria, which had a high‐density population of an introduced deer species, Sambar (Cervus unicolor), in addition to several native herbivore species. One of the three key assumptions of the Seedling Ratio Method was not supported, whereas conventional differential exclosures showed clear and separate impacts by Sambar and native herbivores. We conclude that the Seedling Ratio Method could not provide a clear indication of browsing impact on forest understoreys in YRNP.

Rabbits: manageable environmental pests or participants in new Australian ecosystems?

Some theorists argue that plant and animal species introduced to new localities should be controlled only if they cause damage and not because they originated in another country; this warrants greater acceptance of introduced species as participants in new ecological associations in a rapidly changing world. To evaluate this concept and its relevance in setting directions for rabbit control in Australia, this idea is not only reviewed against information on the rabbit’s impact in Australian ecosystems but also against management policies, industrial drivers and social expectations. It is concluded that wild rabbits hold many natural Australian ecosystems in a degraded state and any beneficial ecological roles rabbits provide are small by comparison. Furthermore, rabbits can be controlled adequately to initiate ecosystem restoration. The idea that introduced rabbits should be more readily accepted as participants in new ecosystems is strongly counter-argued. Rabbits are not harmless passengers in Australian ecosystems and, to achieve ecosystem recovery, a high level of rabbit control is necessary.

A reference linkage map for Eucalyptus

BackgroundGenetic linkage maps are invaluable resources in plant research. They provide a key tool for many genetic applications including: mapping quantitative trait loci (QTL); comparative mapping; identifying unlinked (i.e. independent) DNA markers for fingerprinting, population genetics and phylogenetics; assisting genome sequence assembly; relating physical and recombination distances along the genome and map-based cloning of genes. Eucalypts are the dominant tree species in most Australian ecosystems and of economic importance globally as plantation trees. The genome sequence of E. grandis has recently been released providing unprecedented opportunities for genetic and genomic research in the genus. A robust reference linkage map containing sequence-based molecular markers is needed to capitalise on this resource. Several high density linkage maps have recently been constructed for the main commercial forestry species in the genus (E. grandis, E. urophylla and E. globulus) using sequenced Diversity Arrays Technology (DArT) and microsatellite markers. To provide a single reference linkage map for eucalypts a composite map was produced through the integration of data from seven independent mapping experiments (1950 individuals) using a marker-merging method.ResultsThe composite map totalled 1107 cM and contained 4101 markers; comprising 3880 DArT, 213 microsatellite and eight candidate genes. Eighty-one DArT markers were mapped to two or more linkage groups, resulting in the 4101 markers being mapped to 4191 map positions. Approximately 13% of DArT markers mapped to identical map positions, thus the composite map contained 3634 unique loci at an average interval of 0.31 cM.ConclusionThe composite map represents the most saturated linkage map yet produced in Eucalyptus. As the majority of DArT markers contained on the map have been sequenced, the map provides a direct link to the E. grandis genome sequence and will serve as an important reference for progressing eucalypt research.

Biodiversity of Terrestrial Ecosystems in Tropical to Temperate Australia

During the short period of annual foliage growth in evergreen plant communities, aerodynamic fluxes (frictional, thermal, evaporative) in the atmosphere as it flows over and through a plant community determine the Foliage Projective Covers and leaf attributes in overstorey and understorey strata. The number of leaves produced on each vertical foliage shoot depends on available soil water and nutrients during this growth period. The area of all leaves exposed to solar radiation determines net photosynthetic fixation of the plant community throughout the year. In turn, the species richness (number of species per hectare) of both plants and resident vertebrates is determined. The species richness of unicellular algae and small multicellular isopods in permanent freshwater lagoons in Northern Australia may possibly have been increased by radiation released from nearby uranium deposits. Evolution of new angiosperms probably occurred in refugia during periods of extreme drought. When favourable climates were restored, the vegetation expanded to result in high Gamma Biodiversity (number of plant species per region) but with each major plant community having essentially the same species richness (number of plant species per hectare). The probable effects of pollution and Global Warming on biodiversity in Australian ecosystems, that experience seasonal drought, are discussed.

Fire regimes and biodiversity in Victoria’s alpine ecosystems

Landscape-scale fires occur in Australian alpine ecosystems once or twice per century, primarily when ignition, regional drought and severe fire weather coincide. When alpine vegetation does burn, there is considerable variation in landscape flammability and fire severity. Regeneration following extensive fires of 2003 and 2006-07 across the Bogong High Plains is occurring in all plant communities (heathlands, grasslands, herbfields and wetlands). In heathland and grassland, vegetation composition has converged towards the long-unburnt state (&gt; 50 years) eight years post fire. There was little effect of variation in fire severity on patterns of regeneration in heathland. In burnt wetlands, Sphagnum cristatum and other dominant species are regenerating; the cover of obligate seeding ericaceous shrubs two years post-fire was positively related to the cover of Sphagnum. The endangered mammal Burramys parvus is also capable of persisting in the alpine landscape after individual large, landscape fires. We conclude that there is no scientific evidence that these fires necessarily had ‘disastrous’ biodiversity consequences. After extensive landscape fires, the primary management objective should be to allow burnt alpine ecosystems to regenerate with minimal subsequent disturbance. Monitoring ecological change in the coming century will be essential for effective management of both fire and biodiversity in alpine ecosystems in Victoria and elsewhere in Australia.

Is the Asian house gecko, Hemidactylus frenatus, really a threat to Australia’s biodiversity?

Invasive animals can have a wide range of impacts in natural systems. The introduced Asian house gecko Hemidactylus frenatus has invaded widely in Australia, but is largely restricted to human-altered landscapes. Hoskin (2011) has argued that H. frenatus has the potential to negatively impact Australian ecosystems by invading natural habitats. We examine this contention by reviewing an extensive standardised fauna survey dataset collected in northern and central Queensland during the key period of H. frenatus expansion from the 1990s to 2012. In light of these data we also re-examine data from other areas that suggest H. frenatus is a benign threat and is unlikely to become an environmental pest within Australia. On current evidence, we conclude that H. frenatus is unlikely to spread much beyond areas of human influence.