Wildlife are important hosts of ticks that pose public health risks around the globe. Some hosts live in close proximity to humans, which can lead to the spread of ticks into human-dominated landscapes. In Australia, bandicoots are often suspected to be the primary host of ticks. Yet, we have a poor understanding of how the urban host assemblage and landscape features drive tick occurrence, particularly in Sydney’s Northern Beaches where tick encounters are frequent and tick-borne allergies are increasing.

Here, we report on an online survey of Northern Beaches residents that aimed to determine the drivers of urban wildlife and tick encounters in yards. We examined how the characteristics of yards and nearby natural landscapes relate to the presence of ticks and wildlife hosts. We received 604 responses, with 77.9% of respondents reported encountering ticks in their yard. Possums (n = 532) were the mostly commonly reported animal followed by brush-turkeys (n = 458) and bandicoots (n = 436). Frequent garden watering and the use of mulch were positively associated with regular possum and bandicoot sightings in yards, but not brush-turkey or rat sightings. Regular possum, brush-turkey and bandicoot sightings were positively associated with the presence of ticks, but not all residents with regular visits from those hosts had a tick problem, indicating that factors beyond host presence influence tick occurrence in yards. Our results reveal some of the drivers of ticks and their hosts at multiple scales in urban areas to inform practical landscape-scale tick management solutions.

Amphibians are the most threatened vertebrate class, with approximately one third of all species at risk of extinction. Like other vertebrate classes, habitat loss and degradation are key threats to amphibians. However, on top of habitat loss, uniquely, many amphibian species are also threatened by infectious diseases, whose emergence has been facilitated by anthropogenic trade and the associated breakdown of dispersal barriers. The global spread of the fungal pathogens Batrachochytrium dendrobatidis and B. salamandrivorans, which cause the disease chytridiomycosis in amphibians, has been associated with widespread amphibian declines. Here we present a spatio-temporal assessment of the global impacts of amphibian chytridiomycosis. We estimate that chytridiomycosis has contributed to the decline of 501 amphibian species over the past half-century, including 90 presumed extinctions. The number of declining species increased rapidly during the 1970s and peaked in the 1980s. The effects of chytridiomycosis have been greatest in large-bodied, range-restricted anurans in wet climates. Chytridiomycosis has caused declines across a broad range of amphibian families, with declines clustered in the Americas and Australia, but also scattered across Europe and Africa. Encouragingly, 60 species have shown signs of recovery, with increases in abundance and distribution reported. However, chytridiomycosis continues to be an ongoing threat for 197 species. Both B. dendrobatidis and B. salamandrivorans remain absent from some regions with high amphibian biodiversity, and limiting ongoing spread is a conservation priority. Preventing further chytridiomycosis-driven amphibian declines is dependent on developing effective mitigation actions to conserve species at high risk of extinction.

Chytridiomycosis, a fungal disease caused by Batrachochytrium dendrobatidis (Bd), is decimating amphibian populations globally. Unfortunately, we lack effective broad-scale management options to reduce chytridiomycosis impacts. Habitat manipulation has shown promise because Bd growth and survival are lower in warmer habitats. In addition, recent evidence suggests that chytridiomycosis risk is less severe when the thermal tolerance of an amphibian host differs from that of Bd. Could the thermal physiology of, and microclimate conditions experienced by, impacted amphibian species be used to predict the threat posed by chytridiomycosis? To answer this question, we measured the thermal physiology (e.g., basking behaviour, preferred and tolerated temperatures) of Litoria raniformis, a threatened amphibian species. We used these data to parameterise a biophysical model that predicted hourly frog body temperatures at a range of sites with different microclimates, which we in turn used to assess chytridiomycosis risk. Litoria raniformis has a broad temperature preference (12.8-24.8° C) and tolerance range (5.5-38.0° C). Hopping distance was maximised after short-term exposure to 34.0° C and maximum basking temperature was 30.8° C. Biophysical modelling predicted that individuals at sites with low shade can achieve and maintain body temperatures that suppress Bd growth, highlighting the importance of managing L. raniformis habitat to ensure open space is available. The integrative approach developed here shows great promise for evaluating chytridiomycosis risk at sites with differing habitat characteristics, and can be adapted for other species of frog threatened by chytridiomycosis.

Australia is in a unique situation in that it is the last major land mass to be free of Varroa destructor- a parasitic mite which, through its association with deadly viruses, can cause large scale honey bee colony losses. These viruses are largely generalists capable of infecting diverse hosts and increased virus loads in honey bees can result in spillover to native pollinators, the effects of which remain uncertain. While we know Australian honey bees are generally healthy, little is known about the health of our native pollinators: taxa which will become all the more important if, or when Varroa arrives. As such, we investigated the prevalence of honey bee-associated viruses in pollinators visiting apple flowers during peak bloom, when great numbers of pollinators come together to co-forage. We focussed on the five most prevalent viruses in Australian honey bees, as well as two common fungal parasites. We found pathogen prevalence in honey bees to be low; five of the seven pathogens screened for were present in <12% individuals. In native species, this was lower still; 55% of native species did not test positive for any pathogen screened for. However, whilst prevalence was low in native taxa, there were differences between taxa and phylogenetic analysis of virus fragments revealed the same strains were circling between different species suggesting that interspecies transmission is occurring. This highlights the need for taxon-specific monitoring and management strategies to protect not only honey bees, but also native pollinators when Varroa arrives.

Climate change is an increasing challenge that impacts a multitude of species globally. Plants are particularly at risk to the adverse effects of climate change as they may be unable to migrate to more favourable conditions. In order to survive in a changing climate, plants must adapt and respond in their current range. Our study uses the “resurrection” technique, comparing old seeds stored in seed banks with modern seeds to determine if plant species are showing changes in traits through time. When relating these trait changes to changes in climate across a broad range of regions in Australia, we found that plant traits including seed mass, seed shape, seed viability and dormancy, germination rate, plant size and root to shoot ratio were all responding to changes in climate. The climate variables that explained the highest amount of trait change were not mean values but typically climate extremes (e.g. drought and heatwaves) and seasonal variation. This is positive news for the future of plants in an uncertain climate as they may be able to adapt rapidly and survive changes in climate.

The nationally vulnerable Swamp Everlasting, Xerochrysum palustre, is a rhizomatous perennial herb of swamps and seasonal wetlands. It was likely once widespread throughout Victoria, however habitat loss through swamp draining and land use change has limited its range to a few sites in south- eastern Australia. Seven sites where X. palustre was previously known to exist were surveyed, and when present, data on population size and density were gathered. Germination trials under a range of temperatures were conducted with seed collected in the field and seed contributed from herbaria. The results of germination trials show that X. palustre is germinable under a wide range of conditions. However, the continued loss of habitat due to altered hydrology, weed invasion, habitat loss and reduced rainfall is likely to lead to this species status declining.

In grassy ecosystems fire maintains diversity. It is commonly thought that fire promotes regeneration by removing biomass, reducing competition for light and providing gaps for recruitment rather than directly stimulating germination. However, studies investigating response to fire-cues often focus on a small taxonomic range and germination at autumn temperatures. Furthermore, observations made in situ suggest that many species delay germination until winter post-fire. We aimed to experimentally test the prevailing hypothesis that grassy ecosystem species do not germinate in direct response to fire. To do this, germination in response to fire-cues (smoke, heat and heat + smoke) was scored over the autumn-winter germination period ex situ. Seed of 60 species (from 15 families) were treated with fire-cues and placed into incubators set to average autumn (20/10°C) temperatures and then moved into an incubator set to average winter (12/5°C) temperatures for the study region. Data were analysed for all species at a consistent point along the germination curve (i.e. 80% germination for one of the treatments) to investigate response to fire-cues. This prevented overlooking responses of species which delayed germination until winter. Fire-cues enhanced germination of many species, and large responses to fire-cues were present among forbs of the families Asteraceae and Fabaceae. Fire-cues also stimulated germination of the families Asparagaceae, Colchicaceae and Linaceae. Fire-cues did not promote germination of Goodeniaceae and Apiaceae forbs. This study challenges the prevailing hypothesis that many species in grassy ecosystems do not germinate in response to fire, and has important implications for management and restoration.

There were no Environmental Impact Statements conducted when the first Western Australian Sandalwood (Santalum spicatum) trees were commercially harvested and exported to Asia in 1845. Since then, an immeasurable number of trees (mostly more than 100-200 years old) have been pulled from the landscape to feed the sandalwood industry, which peaked at more than 14,000 tons harvested per annum, and continued for decades unchecked and unregulated, with unknown quantities illegally harvested.

Here, I review the irreversible impacts of over-extraction of Western Australian Sandalwood; the current status of the species in the wild; and the implications of the multiple, integrated threats impacting the species: its natural lack of recruitment, overgrazing (particularly by introduced, invasive herbivores), altered fire regimes, climate change, and the loss of critical ecological elements such as seed-caching-and-dispersing critical-weight-range mammals.

As a result of this over-exploitation, the lack of recruitment and the cumulative impact of an escalating suite of threats, sandalwood is now struggling to survive over much of its former range. While there has been considerable research associated with the species’ commercial exploitation, there has been virtually no investigation of the ecological role that sandalwood plays within its natural communities and ecosystems, and the implications of its gradual disappearance. What happens when its gone?

I conclude with recommendations for actions that will need to be taken by land managers to ensure sandalwood persists within its current range in the semi-arid and arid rangelands under warming and drying climatic conditions.

Sarcoptic mange disease is caused by the mite Sarcoptus scabiei and is responsible for animal welfare issues and local population declines in bare-nosed wombats (Vombatus ursinus) across south-eastern Australia. However, the factors influencing the distribution and prevalence of this wildlife pathogen is unknown. Identifying the variables that underpin mange prevalence in populations is important, as it allows us to associate risk factors for outbreaks, such as what was observed at Narawntapu National Park, Tasmania. Here I identify environmental attributes and landscape factors which influence the distribution and prevalence of mange in wombat populations by using Tasmanian-wide observational data, sourced from multiple camera trapping networks ranging from 2016 to the present. Occupancy modelling was used, in conjunction with individual mange scores, and fine-scale environmental and landscape data to assess which direct (such and environmental, climatic and habitat variables), and indirect factors (such as landscape features and land use types) exacerbate pathogen severity. Specifically, preliminary results show that low temperature and high humidity, as well as agriculture were likely to be important risk factors for mange prevalence and distribution in Tasmania. Broadly, understanding the host-pathogen interaction within the environment is an essential foundation for further studies, particularly as state-wide distributional data shows a wholistic picture; enabling conservation efforts to focus on areas which may be of most threat to bare-nosed wombat populations.

Mountainous regions include cold climates that are expected to shelter many plant species from the impacts of climate change over the coming century. However, these simple forecasts of upslope migration do not consider that plant species may be limited in their ability to disperse their seeds upslope across steep elevation profiles in mountainous regions. In this study I tested for an upslope dispersal limitation in mountainous regions by determining whether fewer foreign species occurred within seed banks at higher elevations within the alpine zone of Kosciuszko National Park. High elevation sites in this study were located on wind-exposed ridges, whilst medium and low elevation sites were located within sheltered valleys. Contrary to a simple model of distance-limited dispersal, there was a significantly greater proportion of foreign species within seed banks at higher elevations compared to middle and low elevations (P<0.001). The proportion of foreign species with wind-dispersal traits was also greater at higher elevations (P<0.001). These results indicate that wind-dispersed seeds may have no trouble reaching the highest sites, but in comparison, miss sheltered environments at mid-elevation mountainous regions. Simple forecasts of distance-based migration will not be sufficient to forecast upslope migration in mountainous regions. Wind-dispersed seeds may readily reach wind-exposed areas of mountainous regions, but those species may or may not be able to withstand the harsh conditions of such environments. Dispersal limitation may be more pronounced in the sheltered mid-elevation areas, which may be missed refugia as the seeds blow to the summits.