Arid Australia Research Articles

A new species of rock skink (Scincidae: Liopholis) from the Central Ranges bioregion of arid Australia

A new species of rock skink (Scincidae: Liopholis) from the Central Ranges bioregion of arid Australia

Biogeography of Australian Camphorosmeae and Diversification in Climatic Space and Across Arid Habitat Types.

This study investigates the biogeography of the Australian Camphorosmeae (Amaranthaceae s.l.) lineage and how it relates to shifts in climatic niche and habitat types. Building on previous research and data resources, we integrate molecular phylogenetics, bioclimatic data and biogeographical models to deepen our understanding of the diversification and adaptation of this group across Australia's diverse landscapes in relation to palaeoclimatic changes. For 159 species representing 12 genera, georeferenced distribution points were used to define the most informative bioclimatic variables using principal component analysis. Evolutionary shifts in climatic niches and habitat types were analysed, revealing clade-specific shifts and adaptations to different habitats and climatic conditions. Biogeographical analyses allowed us to infer ancestral areas of Camphorosmeae in Australia and relate their expansion over evolutionary time to habitat shifts. Preadaptation of this group to warm and dry habitats coupled with key periods of aridification in Australia, particularly during the Late Miocene to Pliocene, were critical in driving its diversification through migration and local adaptation to varied habitats of arid Australia. Our analyses suggest that the 'Riverine Desert' habitat offered suitable conditions for ancestral Australian Camphorosmeae and facilitated their early widespread dispersal in the Western and Eastern Desert. We hypothesise that early diverging lineages such as Roycea adapted to the later emerging 'Desert Lake' habitat when it spread in Western Australia during the Early Pliocene. Further, habitat type shifts occurred from 'Riverine Desert' to 'Shield Plain', 'Karst Plain' and to 'Sand Desert' also during the Pliocene and Pleistocene once these habitat types emerged. This study illustrates the complex interplay between ecological flexibility and niche conservatism in shaping the biodiversity of Australian Camphorosmeae.

Rebalancing Regional and Remote Australia: a vision for a global carbon sink while creating sustainable communities

Abstract This paper introduces a visionary strategy, Rebalancing Regional and Remote Australia. It aims at transforming Australia into a significant global carbon sink by sequestering 4 gigatonne (Gt) of CO2 equivalent annually, leveraging about 25% of the nation’s landmass. Addressing the unique challenges of Australia’s arid climate, the plan employs innovative, proven solutions in energy, water, and agriculture, including agrivoltaics, to enhance sustainability across diverse environmental and socioeconomic contexts. A central pillar of the plan is the creation of sustainable regional and remote communities. Designed for scalability, it begins with a pilot community of 100 000 residents, showcasing the initiative’s feasibility and potential for significant return on investment. Beyond its environmental objectives, the plan presents substantial business opportunities, positioning Australia as a leader in global sustainability efforts. Through collaborative innovation, it offers a model for national and international action, highlighting the imperative for comprehensive strategies that promote economic, environmental, and social advancement.

Seed dispersal by Martu peoples promotes the distribution of native plants in arid Australia

Commensal relationships between wild plants and their dispersers play a key ecological and evolutionary role in community structure and function. While non-human dispersers are often considered critical to plant recruitment, human dispersers have received much less attention, especially when it comes to non-domesticated plants. Australia, as a continent historically characterized by economies reliant on non-domesticated plants, is thus a key system for exploring the ecological role of people as seed dispersers in the absence of agriculture. Here, we utilize a controlled observation research design, employing ecological surveys and ethnographic observations to examine how seed dispersal and landscape burning by Martu Aboriginal people affects the distribution of three preferred plants and one (edible, but non-preferred) control species. Using an information theoretic approach, we find that the three preferred plants show evidence of human dispersal, with the strongest evidence supporting anthropogenic dispersal for the wild bush tomato, Solanum diversiflorum.

Spatial variability in the contribution of termites to the decay of plant detritus

AbstractDrylands are characterized by high spatial variability in resource availability due to sporadic rainfall, topography of the landscape and important effects of animals. Resource availability gradients may trigger patterns in decomposer population abundances and activity, which could affect ecosystem functions such as decomposition. Here, we examined the influence of resource availability gradients on the importance of termites in the decomposition of wood and grass litter. We placed wood blocks and grass litter baits in bags accessible and inaccessible to termites across wood and grass resource gradients as determined by the presence or absence of a top mammalian predator and across topographic gradients during a 9‐month period in arid Australia. We hypothesized that grass‐eating termite activity would track grass abundance and wood‐eating termite activity would track wood abundance. Termites were the predominant decomposition agent at these sites. Termites contributed to 99.5% of wood decomposition and 83.9% of grass decomposition during our study period. For wood, the termite effect was spatially variable and increased with habitat wood availability, which was greatest on dunes and where top predators were absent. However, the contribution of termites to grass litter decomposition did not track grass availability or termite abundance. The highest effects of termites on grass decomposition rates were found in habitats where the absence of top predators led to low grass availability. Our findings highlight how spatial variability in resources in addition to other factors that we do not document but are known to be influenced by the presence of top predators, such as insectivore predation rates, across the landscape could affect ecosystem functions such as decomposition.

The heat is on: Thermoregulatory and evaporative cooling patterns of desert-dwelling bats

For small endotherms inhabiting desert ecosystems, defending body temperatures (Tb) is challenging as they contend with extremely high ambient temperatures (Ta) and limited standing water. In the arid zone, bats may thermoconform whereby Tb varies with Ta, or may evaporatively cool themselves to maintain Tb < Ta. We used an integrative approach that combined both temperature telemetry and flow through respirometry to investigate the ecological and physiological strategies of lesser long-eared bats (Nyctophilus geoffroyi) in Australia's arid zone. We predicted individuals would exhibit desert-adapted thermoregulatory patterns (i.e., thermoconform to prioritise water conservation), and that females would be more conservative with their water reserves for evaporative cooling compared to males. Temperature telemetry data indicated that free-ranging N. geoffroyi were heterothermic (Tskin = 18.9–44.9 °C) during summer and thermoconformed over a wide range of temperatures, likely to conserve water and energy during the day. Experimentally, at high Tas, females maintained significantly lower Tb and resting metabolic rates, despite lower evaporative water loss (EWL) rates compared to males. Females only increased EWL at experimental Ta = 42.5 °C, significantly higher than males (40.7 °C), and higher than any bat species yet recorded. During the hottest day of this study, our estimates suggest the water required for evaporative cooling ranged from 18.3% (females) and 25.5% (males) of body mass. However, if we extrapolate these results to a recent heatwave these values increase to 36.5% and 47.3%, which are likely beyond lethal limits. It appears this population is under selective pressures to conserve water reserves and that these pressures are more pronounced in females than males. Bats in arid ecosystems are threatened by both current and future heatwaves and we recommend future conservation efforts focus on protecting current roost trees and creating artificial standing water sites near vulnerable populations.

Diversification of Camphorosmeae (Amaranthaceae s.l.) during the Miocene-Pliocene aridification of inland Australia

The Australian Camphorosmeae represent a monophyletic lineage that diversified to include ca. 150 spp. across 12 genera, and populate large parts of arid Australia. Tracking the origin and spread of this ancestrally salt and drought tolerant lineage provides additional evidence about the timing of the evolutionary history and phylogenetic assembly of arid habitats in Australia. Using a customized RADseq approach, sequence data for 104 species of the Australian Camphorosmeae representing all 12 genera were generated and included in phylogenetic and dating analyses. Furthermore, habitat type occurrences and preferences of species and clades were recorded. As suspected, the characters used to delimit current Australian Camphorosmeae genera do not support monophyletic groups, as phylogenetic analyses yielded 17 statistically supported clades across a large Maireana grade and crown radiation of Sclerolaena. The diversification of Australian Camphorosmeae is clearly linked to landscape changes and emerging new habitat types in arid Australia since the ancestral element likely arrived from temperate semi-arid to arid parts of continental Eurasia in the Middle Miocene. Migration was likely multidirectional and followed a west-to-east aridification. Crown group diversification was strongest during the Pliocene and likely promoted by the west-to-east expansion of Riverine Desert habitats and subsequent expansion and colonization of newly developing arid habitats. Rapid range expansion, fast habitat saturation, as well as periodic expansion, contraction and replacement of arid habitats, may have caused the rather species-poor clades of the earlier-divergent Maireana grade, compared to the continuously diversifying Sclerolaena clade.

Ants of Uluru-Kata Tjuta National Park in arid Australia: Diversity, faunistic composition and habitat associations

Inland Australia supports by far the world's most diverse arid-adapted ant fauna, but there are no published studies of regional ant faunas from the central arid zone. Here we describe the ants collected by pitfall trapping at 22 sites in World Heritage-listed Uluru-Kata Tjuta National Park (300 mm mean annual rainfall), representing all major vegetation types from spinifex grasslands to eucalypt woodlands. A total of 154 (mostly undescribed) ant species from 26 genera were recorded, with the richest genera being Melophorus (30 species), Monomorium (26), Iridomyrmex (18) and Camponotus (12). The pattern of species accumulation suggests that many more species remain to be collected from the Park, and we estimate that the total fauna consists of around 300 species. The most abundant ants were species of Iridomyrmex (collectively contributing 76% of all ants collected), as is the case throughout arid Australia. Species of Monomorium and Melophorus were also highly abundant. No exotic species were recorded. Ant species composition was strongly related to vegetation type, with a particular distinction between the various grasslands on one hand, and woodlands on the other. Unexpectedly, species richness was higher in structurally simple spinifex grasslands than in eucalypt woodlands. The woodland fauna lacks many taxa characteristic of such habitats in similarly arid regions of southern Australia, which we attribute to remoteness and small patch size. Uluru-Kata Tjuta National Park supports an extremely diverse ant fauna, but surveys of other areas are required for an improved understanding of patterns of ant biodiversity in Australia's central arid zone.

The role of shade in influencing dung deposition and nutrient transfer by kangaroos (Macropus spp.) in an arid landscape

Where they occur at high densities, herbivores are likely to impact ecosystems by functioning as nutrient vectors that shift nutrients from areas where they graze to other locations. Such lateral shifts in nutrients are important to understand as they can alter the balance of species interactions and composition of ecological communities. In arid Australia, kangaroo (Macropus spp.) populations have irrupted due to suppression of their chief predator and their presence can have marked impacts on vegetation and soils in areas where they graze. Kangaroos are hypothesised to facilitate the transport of nutrients by ingesting organic material and depositing it in the form of faecal matter and urine under the shade of trees where they rest during the day. Here, we investigate the role that kangaroos and shade play as nutrient vectors and nutrient sinks, respectively. We compared kangaroo visitation and soil nutrients under experimental shades with unshaded areas in an arid landscape with little natural shade. Kangaroo visitation was greatest at shaded plots. Dung accumulation was greater at shaded plots than unshaded plots. Total carbon (TC) was greater in soils within shaded plots than control plots; however, there was no difference in TC between shaded plots and procedural control plots. There was no difference in total nitrogen and plant available phosphorus between shaded, control and procedural control plots. Our findings demonstrate that the presence of shade in an arid landscape influences the microhabitat choice of kangaroos, but only partially supports the hypothesis that nutrients concentrate within the soil under shade.

Boom-bust population dynamics drive rapid genetic change

Increasing environmental threats and more extreme environmental perturbations place species at risk of population declines, with associated loss of genetic diversity and evolutionary potential. While theory shows that rapid population declines can cause loss of genetic diversity, populations in some environments, like Australia's arid zone, are repeatedly subject to major population fluctuations yet persist and appear able to maintain genetic diversity. Here, we use repeated population sampling over 13 y and genotype-by-sequencing of 1903 individuals to investigate the genetic consequences of repeated population fluctuations in two small mammals in the Australian arid zone. The sandy inland mouse (Pseudomys hermannsburgensis) experiences marked boom-bust population dynamics in response to the highly variable desert environment. We show that heterozygosity levels declined, and population differentiation (FST) increased, during bust periods when populations became small and isolated, but that heterozygosity was rapidly restored during episodic population booms. In contrast, the lesser hairy-footed dunnart (Sminthopsis youngsoni), a desert marsupial that maintains relatively stable population sizes, showed no linear declines in heterozygosity. These results reveal two contrasting ways in which genetic diversity is maintained in highly variable environments. In one species, diversity is conserved through the maintenance of stable population sizes across time. In the other species, diversity is conserved through rapid genetic mixing during population booms that restores heterozygosity lost during population busts.

An investigation into the utility of eastern barn owl pellet content as a tool to monitor small mammal diversity in an arid ecosystem

AbstractConsidering several logistical limitations associated with live trapping in arid environments, owl pellet analysis provides a potentially useful alternative to estimate small mammal diversity. Owl pellet analysis has been used to estimate local small mammal diversity under the assumption that the method can reliably reflect the composition of local small mammal assemblages. However, the validity of owl pellet contents for use in ecological assessments has not been established. Thus, the present study aimed to determine the potential for eastern barn owl (Tyto delicatula) pellet analysis to improve the monitoring of small mammals in arid Australia. We analysed two ecological datasets from Pilungah Reserve on the northern boundary of the Simpson Desert in central Australia to assess their effectiveness for detecting expected small mammal species: 250 owl pellets collected from a known roosting site and 5 years of small mammal records from historical, long‐term trapping surveys. Species composition and detection probability of mammals varied depending on the method used. Owl pellet analysis returned higher species richness overall, while traditional trapping methods indicated a higher probability of detecting certain mammal species (e.g., the wongai ningaui Ningaui ridei, brush‐tailed mulgara Dasycercus blythi and the hairy‐footed dunnart Sminthopsis hirtipes). Importantly, analysis of owl pellets revealed two mammal species that had never been detected at the study site (dusky hopping mouse Notomys fuscus and Carpentarian false antechinus Pseudantechinus cf. mimulus). We suggest that owl pellet analysis could be particularly valuable when used as a precursor or in concert with traditional trapping to monitor and assist in the conservation of small mammal species in arid environments.

Influence of interactive effects on long-term population trajectories in multispecies reintroductions.

Reintroduced populations are typically considered to progress through establishment, growth, and regulatory phases. However, most reintroduction programs do not monitor intensively enough to test this conceptual model. We studied population indices derived from track activity of 4 threatened species (greater bilby [Macrotis lagotis], burrowing bettong [Bettongia lesueur], greater stick-nest rat [Leporillus conditor], and Shark Bay bandicoot [Perameles bougainville]) over 23years after multiple reintroductions of each species in arid Australia. We compared population trajectories among species and investigated the effect of time and environmental variables. All species bred immediately after release, and the growth phase lasted 3-16years, varying markedly among but not within species. The end of the growth phase was characterized by an obvious peak in population density followed by either a catastrophic decline and sustained low density (bettongs), a slow decline to extirpation after 20years (stick-nest rat), or a slight decline followed by irregular fluctuations (bilby and bandicoot). Minor fluctuations were related to environmental variables, including 12-month cumulative rainfall and lagged summer maximum temperatures. Three of the 4 species did not reach a regulation phase, even after 23years, possibly due to interspecific competition and trophic cascades triggered by predator removal and multispecies reintroductions. Bilbies and bandicoots exhibited a second growth phase 18years after reintroduction, likely caused by high rainfall and increased resources following the population crash of overabundant bettongs. Our results suggest that assemblages within multispecies reintroductions demonstrate high variability in population trajectories due to interactive effects. Intensive monitoring to assess population viability may require decades, particularly where multiple species are reintroduced, release sites are confined, and the climate is unpredictable. Intensive monitoring also allows for adaptive management to prevent precipitous population declines. Practitioners should not assume reintroduced species pass through predictable postrelease population phases or that viability is assured after a certain period.

Negligible Impact on Precipitation From a Permanent Inland Lake in Central Australia

AbstractFor over a century, numerous proposals for increasing available water in central Australia have been raised, inspired in part by the natural occurrence of the ephemeral lake, Kati Thanda‐Lake Eyre. It has also been proposed that additional rainfall generated by the lake would spread beyond the lake itself, potentially opening up large tracts of uncultivated land to dryland agriculture. Here we use a climate model to examine how adding a permanent lake to Australia's arid center might influence local and regional precipitation. Locally, evaporative cooling from the lake increases low‐level divergence, suppressing precipitation. Regionally, additional moisture from the lake is spread thinly over the Australian continent, resulting in little change to total precipitation. Overall, our results do not support the assertion that maintaining a large inland lake like Kati Thanda‐Lake Eyre in central Australia would significantly increase precipitation, either locally or regionally.

Continuing decline of the common brushtail possum in central Australia

Australia’s recent mammal declines have been most severe in the arid regions, with at least 14 species extinctions occurring therein. The common brushtail possum (Trichosurus vulpecula) is a semi-arboreal marsupial that historically occurred widely across arid Australia but has disappeared from much of this region. We surveyed the last known sites for the species in central Australia. In 2012, we detected possum scats from 3 of 19 sites in Tjoritja National Park in the Northern Territory. Presence sites were separated by &lt;4 km and characterised by extreme ruggedness. Further scat surveys in 2016–17, and 10 499 camera-trap nights of targeted survey in 2020–21, resulted in no possum detections. Moreover, no possums were detected during &gt;60 000 camera-trap nights at nearby monitoring sites targeting other species in 2016–22. The contraction of common brushtail possums to rugged refuges by 2012 is consistent with a decline driven by mammalian predators. The possible extirpation also coincided with or followed record years of high temperatures. The culturally significant common brushtail possum is a priority candidate species for reintroduction to parts of central Australia. Reintroduction attempts must manage mammalian predators and consider the suitability of source populations and translocation sites in the face of a rapidly warming climate.

The influence of drought, precipitation and fossorial mammal reintroduction on the density of fossorial arthropods and their burrows in arid Australia

AbstractThe density and abundance of arid‐dwelling taxa often change significantly in response to precipitation fluctuations and the abundance of their predators. The survival and density of burrowing arthropods and their burrows in arid environments following prolonged dry periods and subsequent rains is poorly understood, as is the potential influence of reintroductions of their predators, such as fossorial mammals. The persistence of these arthropods and their burrows may be important for other species that rely on them for food or use their burrows for shelter. In this study, we examined the density of burrowing and ground‐nesting arthropods and their burrows in Australia's Strzelecki Desert over two years between 2019 and 2021. This period spanned the tail‐end of the worst drought on record and subsequent drought‐breaking rains. We employed a Before‐After Control‐Impact (BACI) study design to examine the short‐term effects of a fossorial mammal reintroduction of the greater bilby (Macrotis lagotis) into predator‐free fenced exclosures and used an inspection camera to detect the presence of spiders and other taxa within individually marked burrows. We observed the largest changes in arthropod abundance and burrow density between a period that encompassed a third consecutive summer in drought and the commencement of drought‐breaking rains, with some taxa declining by as much as 77% (p &lt; 0.001). While the density of harvester ant middens erupted over this time, the density of tarantulas, trapdoor spiders and scorpions declined significantly. The greater bilby reintroduction had no short‐term effect on the densities of the arthropods or their burrows, but their arrival may have implications on their post‐drought recovery. Further studies are needed to determine if the significant declines in arthropod populations and burrows are reflective of normal boom‐bust population dynamics due to the poor natural history knowledge of the arthropods we examined.

Herbivores disrupt the flow of food resources to termites in dryland ecosystems.

Irruption of herbivore populations due to the extirpation of predators has led to dramatic changes in ecosystem functioning worldwide. Herbivores compete with other species for their primary source of nutrition, plant biomass. Such competition is typically considered to occur between species in closely related clades and functional groups but could also occur with detritivores that consume senescent plant biomass. In this study, we tested predictions that in ecosystems where herbivores are not regulated by predators, their indirect impacts on dead vegetation increase with primary productivity and extend to termites that feed on senescent vegetation. We compared dead vegetation cover and termite activity in herbivore exclosures and associated grazed plots at three locations situated along a rainfall gradient in arid Australia where kangaroo populations have irrupted. Dead vegetation cover and termite activity increased with rainfall in ungrazed plots but showed a negligible response to rainfall in grazed plots. Our results suggest that grazing can disrupt the flow of energy to detritivores and decouple the relationship between termite activity and primary productivity. Such disruption could have far-reaching impacts on arid ecosystems because many organisms sit within "brown food webs" that are sustained by energy derived from the decomposition of senescent plant tissues.

Phylogenomics and biogeography of arid-adapted Chlamydogobius goby fishes

The progressive aridification of the Australian continent from ∼ 20 million years ago posed severe challenges for the persistence of its resident biota. A key question involves the role of refugial habitats – specifically, their ability to mediate the effects of habitat loss and fragmentation, and their potential to shape opportunities for allopatric speciation. With freshwater species, for example, the patchiness, or absence, of water will constrain distributions. However, aridity may not necessarily isolate populations if disjunct refugia experience frequent hydrological connections. To investigate this potential dichotomy, we explored the evolutionary history of the Chlamydogobius gobies (Gobiiformes: Gobiidae), an arid-adapted genus of six small, benthic fish species that exploit all types of waterbodies (i.e. desert springs, waterholes and bore-fed wetlands, coastal estuarine creeks and mangroves) across parts of central and northern Australia. We used Anchored Phylogenomics to generate a highly resolved phylogeny of the group from sequence data for 260 nuclear loci. Buttressed by companion allozyme and mtDNA datasets, our molecular findings infer the diversification of Chlamydogobius in arid Australia, and provide a phylogenetic structure that cannot be simply explained by invoking allopatric speciation events reflecting current geographic proximity. Our findings are generally consistent with the existing morphological delimitation of species, with one exception: at the shallowest nodes of phylogenetic reconstruction, the molecular data do not fully support the current dichotomous delineation of C. japalpa from C. eremius in Kati Thanda-Lake Eyre-associated waterbodies. Together these findings illustrate the ability of structural (hydrological) connections to generate patterns of connectivity and isolation for an ecologically moderate disperser in response to ongoing habitat aridification. Finally, we explore the implications of these results for the immediate management of threatened (C. gloveri) and critically endangered (C. micropterus, C. squamigenus) congeners.

Negative frequency dependent prey selection by two canid predators and its implications for the conservation of a threatened rodent in arid Australia

Unprecedented anthropogenic changes to biodiversity and biogeography demand a greater understanding of the consequences of altered faunal composition for ecosystem functioning. Selective predation has important, yet poorly understood effects on ecosystem stability, and can be strongly influenced by the relative frequencies of different prey types in the environment. Yet, how predators adjust their selection for prey according to their environmental frequency is often overlooked. Here, we assessed frequency dependent selection of prey by dingoes and foxes in the Australian desert, biannually, across a nine-year period (2007–2016). Both predators exhibited potentially destabilizing, negative frequency dependent selection for prey. Foxes persisted to preferentially consume a threatened, native rodent (Notomys fuscus) when it was environmentally scarce. Bolstered by the observation that N.fuscus occurs at low densities in areas where foxes are common, our results suggest that N.fuscus is particularly vulnerable to predation by this predator; possibly because it is naïve and/or lacks adaptations to avoid or escape predation by the relatively recently introduced fox. Dingoes tended to consume reptiles when they were scarce; potentially constituting a conservation concern if selected reptilian taxa are threatened. Foxes avoided, thus were unlikely to control populations of overabundant kangaroos, while both foxes and dingoes showed a preference for, and may therefore control populations of invasive rabbits. The integration of our results into the relative suites of (de)stabilizing influences exerted by dingoes and foxes is important to provide a more dynamic insight into how each predator impacts their naturally fluctuating ecosystems.

Mortality rates of desert vegetation during high‐intensity drought at Uluru‐Kata Tjuta National Park, Central Australia

AbstractPrecipitation variability and heatwaves are expected to intensify over much of inland Australia under most projected climate change scenarios. This will undoubtedly have impacts on the biota of Australian dryland systems. However, accurate modelling of these impacts is presently impeded by a lack of empirical research on drought/heatwave effects on native arid flora and fauna. During the 2018–2021 Australian drought, many parts of the continent's inland experienced their hottest, driest period on record. Here, we present the results of a field survey in 2021 involving indigenous rangers, scientists and national parks staff who assessed plant dieback during this drought at Uluru‐Kata Tjuta National Park (UKTNP), central Australia. Spatially randomized quadrat sampling of eight common and culturally important plants indicated the following plant death rates across UKTNP (in order of drought susceptibility): desert myrtle (Aluta maisonneuvei subsp. maisonneuvei) (91%), yellow flame grevillea (Grevillea eriostachya) (79%), Maitland's wattle (Acacia maitlandii) (67%), waxy wattle (A. melleodora) (65%), soft spinifex grass (Triodia pungens) (53%), mulga (A. aneura) (42%), desert oak (Allocasuarina decaisneana) (22%) and quandong (Santalum acuminatum) (0%). The sampling also detected that seedling recruitment was absent or minimal for all plants except soft spinifex, while a generalized linear mixed model (GLMM) indicated two‐way interactions among species, plant size and stand density as important predictors of drought survival of adult plants. A substantial loss of biodiversity has occurred at UKTNP during the recent drought, with likely drivers of widespread plant mortality being extreme multi‐year rainfall deficit (2019 recorded the lowest‐ever annual rainfall at UKTNP [27 mm]) and record high summer temperatures (December 2019 recorded the highest‐ever temperature [47.1°C]). Our findings indicate that widespread plant death and extensive vegetation restructuring will occur across arid Australia if the severity and frequency of droughts increase under climate change.

Designing a large-scale track-based monitoring program to detect changes in species distributions in arid Australia.

Monitoring trends in animal populations in arid regions is challenging due to remoteness and low population densities. However, detecting species' tracks or signs is an effective survey technique for monitoring population trends across large spatial and temporal scales. In this study, we developed a simulation framework to evaluate the performance of alternative track-based monitoring designs at detecting change in species distributions in arid Australia. We collated presence-absence records from 550 2-ha track-based plots for 11 vertebrates over 13years and fitted ensemble species distribution models to predict occupancy in 2018. We simulated plausible changes in species' distributions over the next 15years and, with estimates of detectability, simulated monitoring to evaluate the statistical power of three alternative monitoring scenarios: (1) where surveys were restricted to existing 2-ha plots, (2) where surveys were optimized to target all species equally, and (3) where surveys were optimized to target two species of conservation concern. Across all monitoring designs and scenarios, we found that power was higher when detecting increasing occupancy trends compared to decreasing trends owing to the relatively low levels of initial occupancy. Our results suggest that surveying 200 of the existing plots annually (with a small subset resurveyed twice within a year) will have at least an 80% chance of detecting 30% declines in occupancy for four of the five invasive species modeled and one of the six native species. This increased to 10 of the 11 species assuming larger (50%) declines. When plots were positioned to target all species equally, power improved slightly for most compared to the existing survey network. When plots were positioned to target two species of conservation concern (crest-tailed mulgara and dusky hopping mouse), power to detect 30% declines increased by 29% and 31% for these species, respectively, at the cost of reduced power for the remaining species. The effect of varying survey frequency depended on its trade-off with the number of sites sampled and requires further consideration. Nonetheless, our research suggests that track-based surveying is an effective and logistically feasible approach to monitoring broad-scale occupancy trends in desert species with both widespread and restricted distributions.