Stefania Ondei

Garden management plays a crucial role in reducing bushfire risk at the wildland-urban interface, yet implementation of fire-safe practices remains challenging. An analysis of garden assessments and in-depth interviews with 23 property owners in Greater Hobart, Tasmania, examined how technical, social and emotional factors influence garden bushfire adaptation decisions. Using the Cynefin framework and complexity theory, this study demonstrates that successful adaptation addresses multiple domains of complexity, from straightforward vegetation management to complex socio-emotional attachments to garden spaces. Findings reveal that while personalised garden assessment reports can motivate change, their success depends on a broader set of conditions. Barriers include practical constraints (e.g. green waste management), emotional attachments to garden elements and difficulties obtaining context-specific guidance. By applying the As Low As Reasonably Practicable (ALARP) principle, this study identified cost-effective interventions across the 4 avenues of institutional support and resource management, individual garden bushfire adaptation, personalised technical guidance and community support networks. This research suggests that creating fire-adapted gardens requires coordinated support systems that address both practical implementation challenges and emotional connections to garden spaces.

The Australian tropical savanna is among Earth’s most fire-prone regions. For millennia, Aboriginal Australians used prescribed burning to improve habitats for food plants and herbivores and to mitigate high intensity fires ignited by lightning in the late dry season. However, these practices were rapidly and profoundly interrupted beginning in the late 19th and early 20th centuries with the arrival of European pastoralists. Some studies have suggested that as a result of this reduction in early dry season, low intensity burning, late dry season, high temperature fire activity increased, with deleterious effects on ecosystems. However, as Aboriginal burning was curtailed, the introduction of cattle (as well as sheep and donkeys) reduced the grassy fuel layer. Developing a clear picture of baseline fire activity prior to the pastoralist era is important because bushfire intensity modulates greenhouse gas emissions from tropical savannas and modulates savanna and rainforest ecosystem dynamics. Reconstructing bushfire frequency and intensity is complicated by limited historical records of burning prior to the late 20th century, and few naturally-occurring, high-resolution, fire-sensitive archives.In order to place 20th century bushfire into a long-term context, we reconstructed fire activity at sub-decadal resolution for the majority of the last millennium using polycyclic aromatic hydrocarbons (PAH) in three precisely-dated and fast-growing stalagmites from cave KNI-51, located in the tropical savanna of northeastern Western Australia. The molecular weights of PAH are tied to combustion temperature (i.e., higher molecular weights (HMW) form at higher temperature fires), and thus our record preserves evidence of both the timing and temperature of bushfire. In order to integrate the multiple stalagmites used to construct this composite record, we normalized each PAH class (low and high molecular weight) to the total PAH abundance in each sample.The KNI-51 stalagmite record reveals that high temperature fire was a regular component of the Australian tropical savanna throughout the last millennium, suggesting late dry season fires were commonplace. However, soon after the arrival of European pastoralists in the 1880s, the frequency of high temperature fires decreased markedly and remained low until the record end of the KNI-51 record in 2009 CE. This shift in bushfire regime, which is apparent based on decadal averages of normalized HMW PAH and through breakpoint analysis, occurred despite severe reductions of early dry season burning by Aboriginal Australians. It also occurred during a monsoon rainfall regime, determined using oxygen isotope ratios from the same stalagmites, that was close to the last millennium average. Thus, after discounting prescribed burning and hydroclimate, we ascribe this decrease in high temperature bushfire to reductions by cattle of grassy fuel loads. The anomalous nature of the 20th century Australian tropical savanna pyroscape in the area of KNI-51 highlights the complexities associated with re-establishing the pre-pastoralist era bushfire regime in this region.

Background: The creation of defensible space, an area around the house where fuel is managed according to specific guidelines, can reduce ignition and fire spread, mitigating wildfire threat to communities. Remote sensing approaches can facilitate assessments of defensible spaces. Aims: To develop a protocol to evaluate which defensible space hazards can be accurately assessed using Light Detection and Ranging (LiDAR). Methods: We used high and low point density airborne LiDAR to measure hazards in 31 gardens in southeast Tasmania (Australia) based on alignment with defensible space guidelines. We compared the resulting ‘garden hazard scores’ with those generated from field observations to identify garden characteristics that can be estimated using LiDAR, as well as the best analysis resolution to do so. Key results: We found a good association between field data and LiDAR measures of vegetation cover and spatial arrangement, but not plant flammability, inferred using Normalised Difference Vegetation Index (NDVI), or flammable objects. Low-density LiDAR consistently underestimated cover metrics compared with High-density LiDAR. Nonetheless, garden hazard scores calculated using either high- or low-density LiDAR yielded results similar to those obtained using only field observations. Implications: LiDAR can be used to conduct semi-automatic, large-scale measurements of some, albeit not all, critical garden hazards.

Expert‐derived range maps are used extensively in macroecological and biogeographic analyses, yet they are subjective, taxonomically biased, and inconsistent in their treatment of species' absences. We developed a reproducible, data‐driven approach to estimate species' extent of occurrence (EOO) using presence‐only data and subregions of the Interim Biogeographic Regionalization for Australia (IBRA). This approach employs a Gaussian kernel density estimator calibrated for spatial coherence and ecological realism, producing maps independent of arbitrary grid structures. We applied it to 610 Australian bird species and evaluated the concordance of our data‐driven EOO maps against BirdLife International expert‐derived range maps. The spatial association between these two map sources, measured on a 0–1 scale, ranged from near‐zero to 0.93 across species, with higher concordance among terrestrial birds. Estimates of richness using both map sources varied most at the finest spatial scale (IBRA subregions), with mean and root mean square errors at the coarsest biogeographic scale (ecoregion) being 1/3 lower than those at the subregional scale. Likewise, we demonstrated the approach's applicability across taxa by generating data‐driven EOO maps for selected amphibians, mammals, reptiles, and vascular plants. Like for birds, discontinuities in the distribution of these non‐avian species represented different subpopulations over Australia. Our approach minimizes the influence of sampling bias and internal discontinuities in the estimation of species' EOO, while allowing for range edge refinement and subpopulation delineation. It provides an objective and scalable alternative to expert‐derived range maps, well‐suited for large‐scale ecological research requiring consistency in spatial precision. Given the plethora of biogeographic templates already in use, our approach is adaptable to many contexts and thus can readily support a better understanding and conservation of biodiversity at large spatial scales.

Background: Wildfires increasingly threaten communities at the wildland–urban interface, where effective garden management is crucial for reducing house loss. Aims: To understand barriers and opportunities for implementing garden wildfire prevention strategies by examining how residents’ risk perceptions align with assessed hazards and exploring factors influencing garden management decisions. Methods: We conducted a multi-modal study of 23 homeowners in Greater Hobart, Tasmania, Australia, combining quantitative survey, qualitative interviews, mapping exercises and photo-elicitation. Gardens were classified into risk categories based on biophysical assessments of both garden and landscape fire hazards, and the social data were analysed according to this framework. Key results: Significant discrepancies existed between perceived and actual hazards, particularly in zones closest to houses (0–1.5 m). While participants recognised landscape-level fire risks, they underestimated hazards in their own gardens and focused on plant flammability rather than spatial arrangement. Personalised garden hazard assessment reports effectively motivated change, especially among residents in high landscape-risk areas. Implementation barriers included knowledge gaps, resource constraints and emotional attachment to garden elements. Conclusions: Garden fire risk reduction requires flexible frameworks that respect resident values while emphasising critical near-house zones. Implications: Future interventions should combine property-specific assessments with community-based support systems to bridge the gap between awareness and implementation of garden safety measures.

Australia has long been recognized as one of the world’s fire hotspots, but the Black Summer of 2019-2020, when 97,000 km2 were scorched across southeastern Australia, and the larger fires of northern Australia’s savanna and desert in 2023, may indicate a shift toward a higher level of fire activity. Placing these events in context requires developing precisely-dated, high resolution records of bushfire through periods with different climate and land use mean states. We reconstructed bushfire activity for the period 1110-2009 CE using polycyclic aromatic hydrocarbons (PAH) in three precisely-dated, fast-growing, and partially overlapping aragonite stalagmites from cave KNI-51, located in the central Australian tropical savanna. PAH molecular weights are tied to combustion temperature (i.e., low molecular weights form in lower temperature fires), and thus our record preserves evidence of both the timing and intensity of bushfire over the majority of the last millennium.Comparisons of burn scar satellite imagery with temporal changes in PAH abundances in recently deposited stalagmite suggest that airfall (smoke and ash) from fires within a 5 km radius is primarily responsible for transmitting PAH to the land surface over the cave, a finding supported by our recent controlled burn and irrigation experiment. The rapid growth rate of KNI-51 stalagmites (1-2 mm yr-1), coupled with the extremely thin soils above the cave, appear to allow for transmission and preservation of multi-annual paleofire signals.To investigate the effects of external forcing on bushfire activity over the last millennium, we applied linear mixed-effect regression to the PAH data, and also included monsoon rainfall (using oxygen isotope ratios from the same stalagmites), annual surface air temperature (using output from the CESM-Last Millennium Ensemble), antecedent fire (using the same stalagmite PAH record), and timing with respect to the arrival of European pastoralists (EP) and their cattle in the 1880s.The model reveals significant differences prior to and following the arrival of EP. Most notably, prior to the arrival of EP, rainfall was significantly correlated with low and medium intensity fires, but not high intensity ones. After the arrival of EP, the correlation between rainfall and fire activity decreased markedly, and showed no statistically significant correlation to any fire intensity. Similarly, prior to the arrival of EP, antecedent fire activity (determined as the sum of PAH within the previous 5 years) was correlated with all levels of fire intensity, but after EP arrival, only high intensity fires are correlated with such antecedent burning. Our findings thus suggest that fire activity following the arrival of EP in the eastern Kimberley has been distinct from any other extended period of the last nine centuries.

The Bass Strait islands are the elevated remnants of a now-submerged continental land bridge that connected the mainland of Australia to Lutruwita/Tasmania during low sea level phases of the Quaternery period. The Furneaux Group is made up of around 100 islands, harbouring a rich diversity of plants derived from glacial refugia and stepping-stone dispersal as millennial-scale climate change altered the land and seascape configuration of the land bridge. Despite the region’s significance, long-term ecological and environmental dynamics of most of these islands remain poorly known. We present the first palaeoecological study of Long Island, a small granite island of the Furneaux group, currently covered by extensive grasslands in the west and patches of forest and woodland in the east and north of the island. We use decadal to centennial-scale resolution palaeoecological evidence for vegetation, animal and fire dynamics, alongside historical accounts of vegetation changes inferred from aerial photo analysis, to develop a comprehensive record of the island’s long-term ecology. Results show that grasslands have been an important feature of the island for at least the last 1000 years, and are reminiscent of Last Glacial Maximum grasslands of the now-submerged Bassian Plain. Both aerial photo analysis and the palaeoecological record show increases in forest cover on the island’s eastern corner over the past four decades. We discuss these ecological dynamics in the context of environmental and climatic shifts. This study emphasises the importance of palaeoecological studies, specifically their value in understanding modern ecosystems in their historic context. This data is critical in understanding the island’s current landscape and how this might change into the future.

Destructive wildfire disasters are escalating globally, challenging existing fire management paradigms. The establishment of defensible space around homes in wildland and rural urban interfaces can help to reduce the risk of house loss and provide a safe area for residents and firefighters to defend the property from wildfire. Although defensible space is a well-established concept in fire management, it has received surprisingly limited scientific discussion. Here we reviewed guidelines on the creation of defensible space from Africa, Europe, North America, South America, and Oceania. We developed a conceptual model of defensible space framed around the key recommended approaches to mitigate fire attack mechanisms, which address fuel types, amount, and spatial distribution. We found that zonation within the defensible space is commonly recommended; reduction (or removal) of all fuels, and particularly dead plant material, is usually suggested in close ( < 1.5 m; Fuel-free zone) proximity to a house. Conversely, in an intermediate space (1.5–10 m; Open zone), guidelines focus predominantly on minimizing fuel horizontal and vertical connectivity. Finally, in the outer part of the garden (10–30 m; Tree zone) trees can provide canopy shielding from ember attack and radiant energy, but management of on-ground fuel is still recommended. Evidence from the scientific literature broadly supported these defensible space design elements, although many studies were highly localised. Further empirical and modelling research is required to identify optimal zonation surrounding houses, and to better understand how garden structure, species composition and moisture status affects risk of ignition from embers, radiant heat, and flames.