Kakadu National Park Research Articles

Pyrodiversity trade-offs: A simulation study of the effects of fire size and dispersal ability on native mammal populations in northern Australian savannas

Maximising the spatiotemporal variability of prescribed fire (i.e. pyrodiversity) is often thought to benefit biodiversity. However, given mixed empirical support, the generality of the pyrodiversity hypothesis remains questionable. Here, we use a simulation experiment to explore the effects of spatiotemporal fire patterns on the population trajectories of four mammal species in a northern Australian savanna: northern brown bandicoot (Isoodon macrourus), northern brushtail possum (Trichosurus vulpecula arnhemensis), grassland melomys (Melomys burtoni), and northern quoll (Dasyurus hallucatus). Underpinned by data from a landscape-scale fire experiment, we simulated mammal population trajectories under three scenarios of fire size (ambient, small/dispersed fires, large/clumped fires) and three levels of dispersal ability (low, moderate, high) over a 21-year period across the Kapalga area of Kakadu National Park. The simulated population size of all four species declined markedly, regardless of fire spatial pattern and dispersal ability. However, the predicted final population size (i.e. number of individuals in the final timestep of the simulation) for the northern brown bandicoot, northern brushtail possum and grassland melomys were significantly influenced by fire size, with declines most severe under the small/dispersed fire scenario. Our results suggest that maximising the dispersion of small fires at the expense of disturbance refugia (such as less-frequently burnt areas) may exacerbate the severity of mammal decline. This highlights the importance of considering trade-offs between spatial (i.e. fire dispersion) and temporal (i.e. fire frequency) aspects of pyrodiversity, and the potential risks when applying fire management for biodiversity conservation without a firm understanding of the requirements of the target species.

Toxicity of Zinc to Aquatic Life in Tropical Freshwaters of Low Hardness.

Zinc (Zn) is a metal of potential concern for a uranium mine whose receiving waters are in the World-Heritage listed Kakadu National Park in northern Australia. The chronic toxicity of Zn was assessed using seven tropical species in extremely soft freshwater from a creek upstream of the mine. Sensitivity to Zn was as follows (most sensitive to least sensitive based on 10% effect concentrations [EC10s]): mussel Velesunio angasi > gastropod Amerianna cumingi > fish Mogurnda mogurnda > cladoceran Moinodaphnia macleayi > green hydra Hydra viridissima > green alga Chlorella sp. > duckweed Lemna aequinoctialis, with EC10s (<0.45 µm filtered fraction) ranging from 21 to 320 µg/L Zn and EC50s ranging from 52 to 1867 µg/L Zn. These data were used to inform the risk assessment for the rehabilitation of the mine-site and contribute to the global Zn dataset. Environ Toxicol Chem 2023;42:679-683. © 2023 Commonwealth of Australia. Environmental Toxicology and Chemistry © 2023 SETAC.

Controlling feral ruminants to reduce greenhouse gas emissions: a case study of buffalo in northern Australia

Context The bourgeoning carbon economy is creating novel ways to incentivise conservation management activities that have the co-benefits of reducing greenhouse gas (GHG) emissions and social inequality. Aim To estimate the monetary value of carbon credits that landowners could generate by reducing ecologically destructive feral populations of the Asian water buffalo (Bubalus bubalis) in northern Australia. Methods First, we estimated buffalo enteric emissions based on the population structure of feral buffalo in northern Australia, and discounted the reduction of fire emissions due to the consumption of grassy fuel by feral buffalo. We then predicted the change in buffalo population size across the South Alligator River region of Kakadu National Park under four buffalo management scenarios: (1) no buffalo control; (2) low-intensity buffalo control; (3) moderate-intensity buffalo control; and (4) high-intensity buffalo control. We quantified the reduction of GHG emissions under the three buffalo control scenarios, relative to the scenario of no buffalo control, while discounting the GHG emissions that directly result from buffalo control actions (e.g. helicopter emissions). Key results All three buffalo control scenarios substantially reduced the estimated GHG emissions that would otherwise have been produced. The low-intensity buffalo control scenario was predicted to abate 790 513 t CO2-e over the 20-year simulation, worth USD15 076 085 (or USD753 804 year−1). Our high-intensity buffalo control scenario had the greatest reduction in GHG emissions, with a total net abatement of 913 231 t CO2-e, worth USD17 176 437 (or USD858 822 year−1). Conclusions The potential value of carbon credits generated by controlling feral buffalo populations in northern Australian savannas far exceeds the management costs. Implications The management of feral ruminants could be incentivised by the generation of carbon credits. Such management could simultaneously avoid GHG emissions, generate income for landowners and offer significant ecological benefits.

The return of the kinga (saltwater crocodile): Population ‘bust then boom’ shapes shifting baselines in Indigenous biocultural knowledge in northern Australia

The saltwater crocodile (Crocodylus porosus) can be regarded as a cultural keystone species for many Indigenous societies around the world, including for many Aboriginal clans in northern Australia. Here the regional population of Crocodylus porosus suffered a decline, almost to extinction, with unregulated commercial hunting between the 1940s to the early 1970s. Following protected status, saltwater crocodile populations made a rapid recovery. This research documents the perceptions and experiences of this rapid (within living memory) ‘bust then boom’ saltwater crocodile population change, among a regional group of Indigenous Australians (comprising several clans) from the Alligator Rivers Region of western Arnhem Land and Kakadu National Park in the Northern Territory. Using semi-structured interviews, archival work and on-Country (place-based) learning, significant influences on the continuity of Aboriginal people's contemporary engagement with freshwater Country were identified. In particular, the loss of access to freshwater customary harvesting sites and to key harvested species, and as a driver of adaptive changes in harvesting methods and consumption preferences for saltwater crocodile meat and eggs. Importantly, the experiential losses from restricted access to waterbodies were found to have significant impact on opportunities for inter-generational knowledge transmission, according with more recent applications of the Shifting Baseline Syndrome to Indigenous Ecological Knowledge. Findings demonstrate the need for monitoring and management programs of cultural keystone species, like the saltwater crocodile, to include Indigenous-led biocultural knowledge programs as a means of supporting local and Indigenous Knowledge systems. This is particularly critical in cross-cultural, First Nations, and joint-management contexts.

Seasonal responses of macroinvertebrate assemblages to magnesium in a seasonally flowing stream

Macroinvertebrates can be highly sensitive to elevated salinity in freshwater environments, and are known to respond to saline discharges. Magnesium (Mg) is a mine-related contaminant and is a potential environmental risk to a seasonally-flowing, receiving water stream in Kakadu National Park, located in the wet-dry tropics of Australia. The macroinvertebrate assemblage in the stream in the was characterised at four hydrographic phases, from early wet season flow to early dry season pools at flow cessation. On each of the four occasions representing the respective phases, individuals from the most abundant macroinvertebrate species present were collected and acutely exposed to a range (up to 19) of Mg concentrations under laboratory conditions. Sensitivity of taxa to Mg ranged between 39 mg/L Mg (Caenidae: Tasmanocoenis spp.) and 4400 mg/L Mg (Dytiscidae: Clypeodytes feryi), based on the 50% Lethal Concentration (LC50). Characterisation of the macroinvertebrate assemblage at each hydrographic phase indicated the seasons when Mg-sensitive species were present. Whilst no statistical differences in measures of seasonal sensitivity were found, the macroinvertebrate assemblages present during the early flow period had higher Mg-sensitivity than the assemblages present during other hydrographic phases. This could be attributed to the greater relative proportions of Mg-sensitive taxa (e.g. Ephemeroptera) present at early flow compared to greater relative proportions of more Mg-tolerant taxa (C. feryi and Hydacarina spp.) present during later hydrograph phases, especially periods of lower, or no, flow.

Development of a Site-Specific Guideline Value for Copper and Aquatic Life in Tropical Freshwaters of Low Hardness.

Copper (Cu) is a contaminant of potential concern for a uranium mine whose receiving waters are in the World Heritage-listed Kakadu National Park in northern Australia. The physicochemical characteristics of the freshwaters in this region enhance metal bioavailability and toxicity. Seven tropical species were used to assess the chronic toxicity of Cu in extremely soft freshwater from a creek upstream of the mine. Sensitivity to Cu was as follows: Moinodaphnia macleayi > Chlorella sp. > Velesunio sp. > Hydra viridissima > Amerianna cumingi > Lemna aequinoctialis > Mogurnda mogurnda. The 10% effect concentrations (EC10s) ranged from 1.0 µg/L Cu for the cladoceran Moinodaphnia macleayi to 9.6 µg/L for the fish M. mogurnda. The EC50s ranged from 6.6 µg/L Cu for the mussel Velesunio sp. to 22.5 µg/L Cu for M. mogurnda. Geochemical modeling predicted Cu to be strongly bound to fulvic acid (80%-99%) and of low bioavailability (0.02%-11.5%) under these conditions. Protective concentrations (PCs) were derived from a species sensitivity distribution for the local biota. The 99% PC (PC99), PC95, PC90, and PC80 values were 0.5, 0.8, 1.0, and 1.5 µg/L Cu, respectively. These threshold values suggest that the current Australian and New Zealand default national 99% protection guideline value for Cu (1.0 µg/L) would not provide adequate protection in freshwaters of low hardness, particularly for this area of high conservation value. The continuous criterion concentration predicted by the Cu biotic ligand model for conditions of low pH (6.1), low dissolved organic carbon (2.5 mg/L), low hardness (3.3 mg/L), and 27 °C was 0.48 µg/L Cu, comparable with the PC99. Consideration of the natural water quality conditions of a site is paramount for protective water quality guidelines. Environ Toxicol Chem 2022;41:2808-2821. © 2022 Commonwealth of Australia. Environmental Toxicology and Chemistry © 2022 SETAC.

Double-Differenced dNBR: Combining MODIS and Landsat Imagery to Map Fine-Grained Fire MOSAICS in Lowland Eucalyptus Savanna in Kakadu National Park, Northern Australia

A neglected dimension of the fire regime concept is fire patchiness. Habitat mosaics that emerge from the grain of burned and unburned patches (pyrodiversity) are critical for the persistence of a diverse range of plant and animal species. This issue is of particular importance in frequently burned tropical Eucalyptus savannas, where coarse fire mosaics have been hypothesized to have caused the recent drastic population declines of small mammals. Satellites routinely used for fire mapping in these systems are unable to accurately map fine-grained fire mosaics, frustrating our ability to determine whether declines in biodiversity are associated with local pyrodiversity. To advance this problem, we have developed a novel method (we call ‘double-differenced dNBR’) that combines the infrequent (c. 16 days) detailed spatial resolution Landsat with daily coarse scale coverage of MODIS and VIIRS to map pyrodiversity in the savannas of Kakadu National Park. We used seasonal Landsat mosaics and differenced normalized burn ratio (dNBR) to define burned areas, with a modification to dNBR that subtracts long-term average dNBR to increase contrast. Our results show this approach is effective in mapping fine-scale fire mosaics in the homogenous lowland savannas, although inappropriate for nearby heterogenous landscapes. Comparison of this methods to other fire metrics (e.g., area burned, seasonality) based on Landsat and MODIS imagery suggest this method is likely accurate and better at quantifying fine-scale patchiness of fire, albeit it demands detailed field validation.

Faunal standards for the restoration of terrestrial ecosystems: a framework and its application to a high‐profile case study

Assessments of ecosystem restoration have traditionally focused on soil and vegetation, often with little consideration of fauna. It is critical to include fauna in such assessments, not just because of their intrinsic biodiversity value but also because of the many ecological roles that animals play in restoration processes. However, a widely accepted framework for specifying faunal standards for restoration is lacking. Here we present such a framework, incorporating: (1) the identification of appropriate reference conditions; (2) the taxa to be targeted for assessment; (3) the attributes of these taxa to be measured; (4) acceptable similarity with reference conditions; and (5) robust sampling methodologies for reliable assessment. We illustrate this framework using the restoration program at Ranger Uranium Mine in the Australian seasonal tropics, which aims to establish an environment similar to the surrounding World Heritage‐listed Kakadu National Park, corresponding to “full recovery” according to Society for Ecosystem Restoration's standards. Our case study has especially high restoration standards, but our framework has wide applicability to the specification of faunal standards for ecosystem restoration.

Population collapse of a Gondwanan conifer follows the loss of Indigenous fire regimes in a northern Australian savanna

Colonialism has disrupted Indigenous socioecological systems around the globe, including those supported by intentional landscape burning. Because most disruptions happened centuries ago, our understanding of Indigenous fire management is largely inferential and open to debate. Here, we investigate the ecological consequences of the loss of traditional Aboriginal fire management on fire-exposed savannas on the Arnhem Plateau, northern Australia, using the fire-sensitive conifer Callitris intratropica as a bio-indicator. We contrast Kakadu National Park, where traditional Aboriginal fire management was severely disrupted during the early twentieth century following Aboriginal relocation to surrounding settlements, and an adjacent Aboriginal estate where traditional Aboriginal fire management endures. Since 2006, traditional Aboriginal fire management at this site has been overlaid by a program of broad-scale institutionalized burning in the early dry season, designed to reduce greenhouse emissions. Using remote sensing, field survey, and dendrochronology, we show that on the Aboriginal estate, C. intratropica populations depend on the creation of a shifting patch mosaic of long unburned areas necessary for the recruitment of C. intratropica. However, the imposition of broad-scale fire management is disrupting this population patch dynamic. In Kakadu, there have been extreme declines of C. intratropica associated with widespread fires since the mid twentieth century and consequent proliferation of grass fuels. Fire management in Kakadu since 2007, designed to increase the size and abundance of patches of unburned vegetation, has not been able to reverse the population collapse of C. intratropica. Our study demonstrates that colonial processes including relocation of Indigenous people and institutional fire management can have deleterious consequences that are nearly irreversible because of hysteresis in C. intratropica population dynamics.

Looking After the Rock Art of Kakadu National Park, Australia

ABSTRACT Iconic, magnificent and breathtaking are words often used to describe the rock art of Kakadu National Park in the northern tropics of Australia, which is inscribed on the World Heritage List, due to the very many sites with significant rock art (bim) and the strength of continuing Aboriginal culture. A small but dedicated team of Traditional Owners, Park staff and rock art specialists work on an annual program to monitor, maintain and manage this significant landscape through a collaborative framework. To do this the Cultural Programs team, both Bininj/Mungguy (Aboriginal people) and Balanda (non-Indigenous people), work together, incorporating traditional and scientific knowledge systems to build a cooperative approach to look after rock art in Kakadu. Putting culture first is central to the decolonised program, where western scientific conservation techniques play a secondary supporting role. Culture is the foundation in this living cultural landscape and the voices of the Elders guide the co-designed annual program. Alongside this Indigenous stewardship, knowledge of conservation practices is shared to improve understanding and skills in the professional development of local people, Aboriginal ranger groups and national park staff in managing the Kakadu rock art estate. This is achieved through getting families, old people and the young back to Country (traditional custodial lands), which supports intergenerational exchange of knowledge, maintaining culture and connections to kin, Country and language. Here we demonstrate that by keeping culture central, connections between traditional and scientific approaches to protecting, conserving and managing rock art can advance best practice so that bim can endure.

Coproduction mechanisms to weave Indigenous knowledge, artificial intelligence, and technical data to enable Indigenous-led adaptive decision making: lessons from Australia’s joint managed Kakadu National Park

Most of the planet’s vital ecosystems are managed on lands owned by Indigenous peoples. Indigenous people face many challenges in managing these lands, including rapidly growing threats causing species extinctions and ecosystem losses. In response, many Indigenous groups are looking for ethical ways to use digital technology and data analytical tools to support their existing knowledge practices to solve complex environmental management problems. We draw on an action co-research project to show how a range of knowledge coproduction mechanisms were developed and applied to weave Indigenous knowledge, artificial intelligence (AI), and technical sources to monitor the health of Nardab, a culturally significant and Ramsar-listed wetland in Australia's World Heritage-listed Kakadu National Park. The coproduction mechanisms included: holistic assessments of the health of indicators; a dynamic and creative decision-support tool to adaptively manage a complex system; ongoing monitoring and testing of knowledge used for collaborative action; and Indigenous-led governance of research activities and impact at local and regional scales. It was important for local Bininj traditional owners to determine where and how multiple sources of evidence could or should be used and applied to direct and assess on-the-ground actions as part of this collaborative and cross-cultural knowledge sharing and coproduction process. At Nardab, this required negotiating the evidence from qualitative Indigenous-led assessments of significant sites and quantitative ecological information collected and analyzed from cameras and drone surveys. The coproduction mechanisms developed provided a practical and ethical means of empowering different sources of knowledge for adaptive decision making while respecting and protecting differences in how knowledge is generated, interpreted, and applied.

Understanding Indigenous values and priorities for wetlands to guide weed management actions: Lessons from the Nardab floodplain in northern Australia’s Kakadu National Park

SummaryMany wetlands around the world are vulnerable to invasive species and are also culturally important for Indigenous peoples. Yet, translating the complex values Indigenous peoples hold for wetlands into management actions to mitigate the impacts of invasive species can be difficult to put into practice. In this paper, we draw on an Indigenous‐led project on the Nardab wetland in Kakadu National Park to show how understanding the local nuance of Indigenous values and priorities in different wetland places can guide more effective and inclusive weed management activities. At Nardab, Indigenous values and priorities guided the choice of three priority sites to manage the impacts of Para grass (Urochloa mutica) weed. Specific values and priorities were identified across the sites, including significant bush tucker populations, and harvesting sites, the ability for the site to support Indigenous knowledge sharing and ceremonial activities and the opportunity for visitors to enjoy a healthy wetland in this World Heritage Area. The values and priorities varied across the sites, so the actions needed to improve the health of these places were also place specific. The results showed that relationships between Indigenous people and places varied from site to site within a given wetland and could not be easily generalized when deciding on effective management activities. The paper highlights the benefits of supporting ecological, cultural and human‐focused actions that Indigenous people wish to prioritize at selected sites to ensure the management of weed impacts on wetlands adequately reflect the diverse cultural landscapes that are embedded within Indigenous peoples’ Country.

Dig deep to do right [Australia - mining

The restoration of a 40-year-old uranium mine located in unique ecology in the Northern Territory of Australia gives the industry an opportunity to prove that the scars it leaves on the land can, with time, investment, and effort, be fully healed. Kakadu National Park in Australia&apos;s Northern Territory has dual World Heritage listings for its ecological and cultural value. After years of operation, including several expansion projects, and more than 120,000 tonnes of uranium oxide produced, commercial work at Ranger ceased in 2021. The site - which includes a power station, retention ponds, open-mined pits, and tailing dams - will now be rehabilitated for around A$744m. The government wants it restored to a standard "similar to the adjacent areas of Kakadu National Park" so it could eventually be incorporated into the heritage site.

Barriers to fire spread in northern Australian tropical savannas, deriving fire edge metrics from long term high-frequency fire histories

The savannas of northern Australia are amongst the most fire-prone landscapes in the world. However, over the last fifteen years, increasing effort has been put into reducing fire extent and severity using prescribed burning strategies early in the dry season. This study seeks to improve the application of strategic fire management by providing a more detailed understanding of the landscape features that impede fire spread in Australia's tropical savannas using long-term satellite-derived fire histories. Spatial analysis of fire edges in Kakadu National Park based on fine-scale (30 m) Landsat imagery found that most fires stopped along linear edges, which were primarily associated with known features (roads, rivers and cliffs). Further analysis found linear features with the highest stopping ability covered only 13% of the park but divided the whole park into smaller containment regions. The stopping power of each feature type was found to vary according to their width and to change during the fire season, results that could help plan strategic fuel reduction burns. Similar results were seen with the lower-resolution continental-scale MODIS satellite-derived edge data. The MODIS dataset provided a means for applying fire edge analysis to support planning in areas of northern Australia that lack fine scale fire history mapping.

Using knowledge to care for country: Indigenous-led evaluations of research to adaptively co-manage Kakadu National Park, Australia

Using knowledge to care for country: Indigenous-led evaluations of research to adaptively co-manage Kakadu National Park, Australia

Narlim’s Fingerprints: Aboriginal Histories and Rock Art

ABSTRACT This article takes an interdisciplinary approach to understanding Aboriginal rock art artists, drawing together insights from the disciplines of archaeology and biography, as well as from Indigenous knowledge-holders, in order to explore the life and work of a relatively unknown rock painter from western Arnhem Land in Australia: Narlim (born c. 1909). His rock art at Warlkarr (Hawk Dreaming) in Kakadu National Park stands as subtle but powerful testament to his life, his family and unbroken connections to Country. Narlim’s art reveals the ways he creatively engaged with new knowledges and skills introduced by the newcomers to his Country, even as he asserted the enduring traditions and ongoing sovereignty of his people. By reading rock art as a historical source alongside other biographical material, in partnership with Traditional Owners of today, we offer a fresh and holistic approach to better understanding rock art.

Nymphaea kakaduensis (Nymphaeaceae), a new species from the northern portion of the Northern Territory, Australia

Nymphaea kakaduensis C. B. Hellq., A. Leu &amp; M. L. Moody (Nymphaeaceae) is described from Kakadu National Park, Northern Territory. This new species is endemic to the “Top End” of the Northern Territory and was formerly included in N. violacea Lehm. The distinct floral form of N. kakaduensis of having generally smaller flowers with blunt-tipped petals and different coloration than N. violacea instigated a genetic study of taxa from the region. The cpDNA trnL (UAA) - trnF (GAA) intergenic spacer region was sequenced from samples from across northern Australia and a haplotype network analysis was conducted. Plants from populations that had the distinct floral form of N. kakaduensis are found to be genetically distinct from N. violacea in northern Australia sharing 4 SNPs and a notable 23 bp indel in the cpDNA intergenic spacer region to support the morphological attributes and species designation.

Revisiting Francis Birtles’ painted car: exploring a cross-cultural encounter with Aboriginal artist Nayombolmi at Imarlkba Gold Mine, 1929–1930

Inspired by an intriguing photograph of a painted Bean car with Aboriginal designs, this paper explores the cross-cultural encounter between the renowned adventurer Francis Birtles (1881–1941) and Aboriginal artist Nayombolmi (c. 1895–1967). Meeting by chance during one of Birtles’ overland explorations by motorcar and one of Nayombolmi’s annual walking route journeys, the two men came together in an area that would become synonymous with the Imarlkba gold mine in present day Kakadu National Park. Their acquaintance, based on mutual needs and curiosity, provides a rare insight into cross-cultural colonial relationships in this frontier region. Beginning in 1929 their interactions continued intermittently as the Birtles-initiated Imarlkba gold mine developed and Badmardi people (and others) joined the workforce. By revisiting the well-known photograph of Birtles’ painted Bean car, this paper uses a variety of sources, most notably old and new oral history recordings, to investigate Aboriginal histories and colonial cross-cultural engagements in remote northern Australia, and how newly introduced technologies and material culture could be charged with new meanings.

An Analysis of Motif Clusters at the Nanguluwurr Rock Art Site, Kakadu National Park, N. T. Australia

ABSTRACT During recent detailed recording of Nanguluwurr, a rock art site that is part of the Burrungkuy (Nourlangie) complex of cultural sites in Kakadu National Park, Australia, the data showed discrete clusters of specific motif types distributed throughout the length of the gallery. This paper focuses on the spatial distribution of the main motif clusters depicting spirit figures, material culture, fish, and painted hand and forearm motifs in order to understand the significance of these clusters within the site and the significance of Nanguluwurr as part of a wider complex of cultural sites. We consider the concept of these motif groupings as “meaning clusters,” as well as their chronological sequence, and discuss the possibility that they are the result of bursts of painting activity that occurred during the long history of the site manifest through depictions of ancient Dynamic Figures to the recent painting of X-ray fish.

“I Speak My Language My Way!”—Young People’s Kunwok

Bininj Kunwok is a Gunwinyguan language (a non-Pama-Nyungan) spoken in west Arnhem Land and Kakadu National Park, NT, Australia. With around 2500 speakers and children learning it as a first language, Kunwok is one of the strongest Indigenous languages in Australia. Despite its small speech community, it exhibits considerable variation, much of which has been the subject of recent research. One of the primary findings from this study into variation in Kunwok is the rich interspeaker diversity, particularly between different generations of Kunwok speakers. Comparing the speech of young adults and children with that of their elders through a multigenerational corpus has revealed a language change in progress (demonstrated both in real time and apparent time). This paper will discuss three of the key differentiating features of young people’s Kunwok: word-initial engma production, pronominal forms and paradigms and loanwords. We will also examine community members’ perspectives on young people’s Kunwok on the basis that they provide insight into the ideological frameworks that support the linguistic variation and change documented in the community. In conclusion, the paper will summarise the findings, outlining the main features of young people’s Kunwok, and then reflect on the trajectory of Kunwok and the contributions of this study to our understanding of language change in the Australian Aboriginal context.