The paradigm that "pyrodiversity begets biodiversity" postulates that biodiversity increases as the diversity of the fire regime, often measured by times since fire, in a region increases. The pyrodiversity paradigm was derived from a “thought experiment” rather than from explicit theory based on fire ecology and species’ responses to fire regimes. Empirical studies report a diverse range of responses, with researchers suggesting that this diversity can be explained by extra details such as the nuances of individual studies or the complexity of fire regimes and species’ responses. We explore the relationship between pyrodiversity and biodiversity by developing a simple model in which species respond only to time since fire, and calculate biodiversity metrics in landscapes exposed to different distributions of fire intervals. Biodiversity and pyrodiversity are defined in this theoretical framework, with a wide range of relationships between pyrodiversity and biodiversity predicted, even for this simple model in which time since fire is the only driving variable. Biodiversity can increase or decrease with pyrodiversity in different circumstances. An even wider range of relationships between biodiversity and pyrodiversity would be expected in real fire ecology situations that are more complex. Our theoretical analysis shows that inconsistent empirical support for the paradigm “pyrodiversity begets biodiversity” is unsurprising, and that a diversity of relationships between pyrodiversity and biodiversity is expected.

Physical seed dormancy is a key persistence trait for many flowering plants in fire-prone ecosystems with soil heating required to break dormancy. However, field based assessments of both soil temperatures and post-fire regeneration are relatively scarce. Here, we assessed the soil temperature profiles using thermocouples at multiple depths across 10 coupes during their post-harvesting regeneration burn. The coupes were within alpine and mountain ash dominated landscapes typical of wet forest environments. During the burn, soil surface temperatures reached a maximum of 860°C. Below the surface, maximum temperatures ranged from 490°C at 3.5cm depth and 104°C at 5cm depth. The average maximum temperature below the surface (1.5-5cm) ranged from 40°C to 27°C. These relatively low average maximum soil temperatures may be insufficient to break physical dormancy in some fire dependent species. However, duration of soil heating may also be an important factor for species regeneration. Thermocouple data shows soil heating being maintained for longer beneath the soil than at the soil surface. We will present the structural and floristic development within these coupes using annual data up to 4 years post burn. While Victoria has ceased native timber harvesting, this work has important implications for understanding dormancy-breaking temperatures for a range of species in wet forest environments.

Fire regimes in many fire-prone temperate forest landscapes are intensifying under changing climates, with more frequent and severe fires posing potential threats to plant diversity, structure, and regeneration. Nonetheless, while extant understory vegetation and soil seed banks (SSBs) comprise much of the plant diversity in temperate forests, their responses to different fire regime components remain under-evaluated. We conducted a systematic review of studies that examined responses in plant understory diversity to fire in temperate forests. Analyses assessed fire effects on understory richness and abundance across life forms, life span, species origin, fire response strategies, fire regime components, and climatic zones. Relative to unburned conditions, fire of any sort was associated with significant decreases in the diversity (Hedges g’= –0.347) and abundance (g = –0.382) of extant vegetation, and with non-significant decreases in SSB diversity (g = –0.251) and abundance (g = –0.084). Stronger negative effects of fire were indicated for woody (than non-woody) and perennial (than annual) species in extant vegetation, and for non-woody (than woody) and native (than exotic) species in SSBs, reflecting the role of plant traits in mediating plant response to fire. Significant decreases in species richness and abundance in both extant vegetation and SSBs were associated with wildfire, high-severity, and short-interval fires. Negative fire effects were also associated with short time since fire, spring burns, low fire frequency, and dry summer climates in extant vegetation, while in SSBs, stronger negative effects were linked to higher fire frequency and longer time since fire. Our analyses highlight the importance of understanding interactions among plant pools (extant, SSB), plant traits, and fire regime components to anticipate and manage fire impacts on plant diversity in temperate forests.

Rainforests are usually too wet to burn and so provide a natural barrier for fire spread and a potential refuge for biodiversity. However, under hotter and drier conditions, such as prolonged drought, rainforests can transition to a flammable state. The repeated encroachment of fire into rainforests presents a significant conservation challenge, yet our capacity to manage the impacts is hindered by a lack of research on the flammability of rainforests and their constituent species. Fallen leaf and litter bed samples were collected from cool temperate rainforest and eucalypt forest in Willi Willi and Werrikimbe National Parks, New South Wales, Australia. Litter bed flammability of thirteen common temperate rainforest species was measured in the laboratory. The flammability of rainforest litter beds was also measured and compared to fire-prone eucalypt forest litter beds at two different scales (0.07 m2 and 7.2 m2). We also examined links between flammability and key structural and chemical leaf traits. Rainforest species varied in their litter bed flammability, with most (64 %) species exhibiting lower flammability than litter made-up of eucalypt leaves, which typically occur in more fire-prone environments. Species which had smaller leaves and lower leaf cellulose content were associated with lower flammability. Fires in rainforests will vary in intensity depending on the species composition in the litter bed, which depends on the species composition of the area. This study provides key insight into the litter bed flammability of cool temperate rainforests in Australia which is important for the management of wildfires in the future.

Fire drives patterns in biodiversity across the globe. The life history traits of many mammals evolved under specific fire regimes, and as such alterations to these fire regimes can impact population persistence. Our changing climate has already altered many fire regimes, and this is only predicted to increase as our climate continues to warm. Despite knowing that changes to future fire regimes will impact species most of our understanding of fire impacts is limited to how past or current patterns of fire impact mammals. These studies have provided a baseline for understanding species responses to fire and have helped inform contemporary fire management practices. However, they do not account for the conditions species will face in the future. One technique used to determine how future fire regimes may impact mammals involves combining demographic models with fire regime modelling to simulate how populations change through time. Demographic models incorporate an understanding of species life history traits including survival, fecundity, and dispersal, to predict how populations persist. By pairing these models with fire regime models, we can include direct impacts of fire on life history traits as well as indirect impacts on habitat suitability to predict how the fire regime will impact species through time. In this study we combine fire regime modelling techniques including the fire regime operations simulation tool (FROST) with population viability analyses (PVAs) to quantify how different mammals respond to future fire regimes. This work helps us identify mammals at risk from changing fire regimes and helps inform both conservation and land management actions.

Fire management across Australia has to balance the need to protect human lives and infrastructure with the needs of native ecological communities. Under Western fire management frameworks this has typically been addressed through setting fire frequency thresholds that aim to allow enough time between fires for flora and fauna to recover. However, these thresholds are primarily based on the sensitivity of certain plant species to fire frequency and ignore their response to other elements of the fire regime such as severity and season. Additionally, fauna and ecosystem processes are not taken into account in the development of these thresholds. Recently there have been calls for thresholds to be revised or abandoned entirely, with no clear alternatives for how to account for the needs of ecological communities and avoid species declines or community collapse. We propose that part of the solution is an ecosystem level approach, which builds on substantial developments in our understanding of fire ecology for fauna, flora and ecological communities considers the full diversity of species, ecosystem processes and the fire regime. We illustrate the application of it to a Threatened Ecological Community in NSW, Eastern Suburbs Banksia Scrub. We finish by highlighting how it can be adapted and applied more broadly.

Fire regimes play a critical role in sustaining essential ecological functions. However, changes to the frequency, size and severity of historic fire regimes threaten the persistence of fauna. Fire severity – a postfire metric that captures the level of habitat alteration – has a particularly powerful effect on species' capacity to survive and persist after fire. Higher fire severity can increase mortality during fire and influence species’ recovery trajectory after fire. However, species’ responses to increased fire severity are not unidirectional. Functional traits that convey fewer survival advantages, such as aversions for post-fire landscapes or reduced adaptive resilience may correspond with heightened vulnerability to increased fire severity. Additionally, time since the fire and ecosystem type are important contextual elements that may shape species’ responses to severe fire. Through a comprehensive global systematic review, we consolidated literature that assessed individual species’ responses to varying levels of fire severity. We used ordinal logistic regression modelling to test the effects of functional traits, time since fire, taxonomy, and ecosystem type to predict species’ responses to gradients of fire severity. We detected an overarching trend of resilience across all severity comparisons. However, high fire severity elicited greater negative and positive responses than lower severity. More negative responses were associated with species that have weak shelter, forage in the upper canopy, and prefer closed canopies. However, negative responses to high severity fires decreased as the time since fire increased. To safeguard vulnerable species, investing in management that is timely and targeted is crucial. Additionally, we advocate for more research that examines the response of reptiles, amphibians, and mammals to severe fire. Finally, we encourage researchers and practitioners to thoughtfully consider severity assessment metrics to ensure methods match ecological objectives.