Tropical savannas are the world's most fire‐prone biome, and savanna biotas are generally well adapted to frequent fire. However, in northern Australia there are concerns that recent increases in the ...frequency and extent of high‐intensity fires are causing substantial declines in regional biodiversity values. In this paper we use two well‐studied and contrasting faunal groups, ants and small mammals, as case studies for reviewing faunal responses to fire in Australian savannas. The Australian savanna ant fauna is dominated by arid‐adapted taxa that are highly resilient to frequent fire and are not considered to be threatened by prevailing fire regimes. Indeed, frequent fire promotes ant diversity because it maintains an open habit that makes the dominant arid‐adapted taxa feel at home. Long‐term fire exclusion reduces ant diversity due to a marked decline in arid‐adapted taxa, and favours highly generalized, more shade‐tolerant taxa. In contrast, many small mammal species of high conservation value are highly sensitive to frequent fire, and there are widespread concerns that their populations are threatened by current fire management. Many of the species have shown dramatic population declines over recent decades, and, although the causes are poorly understood, there is little doubt that fire is an important contributing factor. It is likely that fire is acting synergistically with other underlying causes of decline, particularly predation by feral cats. The overall resilience of most savanna animal species in relation to frequent fire suggests that they are secure under all but the most extreme fire regimes. However, it is clear that more fire‐sensitive groups such as small mammals need special fire management attention. This needs to involve less frequent and finer‐scale burning, along with the protection of some large, infrequently burnt source areas.
Australia's 2019-2020 mega-fires were exacerbated by drought, anthropogenic climate change and existing land-use management. Here, using a combination of remotely sensed data and species distribution ...models, we found these fires burnt ~97,000 km
of vegetation across southern and eastern Australia, which is considered habitat for 832 species of native vertebrate fauna. Seventy taxa had a substantial proportion (>30%) of habitat impacted; 21 of these were already listed as threatened with extinction. To avoid further species declines, Australia must urgently reassess the extinction vulnerability of fire-impacted species and assist the recovery of populations in both burnt and unburnt areas. Population recovery requires multipronged strategies aimed at ameliorating current and fire-induced threats, including proactively protecting unburnt habitats.
This is an edited version of a keynote address given at the 2023 Ecological Society of Australia conference (https://youtu.be/0JDJ9RdIkP4). I argue that the practice of ecology gifts us a unique ...capability to see and understand the beauty, intricacy and wonder of the natural world, but also powerful insight into biodiversity loss and its consequences. With such privilege we should take more responsibility for its protection. We should recognize that love drives our concern for nature and that emotion renders us more persuasive advocates. Despair at environmental loss is understandable but unhelpful, and we must find hope and build from it. Such hope comes, for example, from a sense of community connection to and concern for nature; in increasingly bold commitments by governments and many organizations to protect biodiversity; in the increased recognition and respect shown in Australia for First Nations management and perspectives on responsibility for country; and in those (albeit still too few) success stories of recovery.
Abbreviated summarizing the article: Ecology is a charmed science, allowing us unique insight into the mystery and wonder of nature. Such knowledge and perception also mean that we can readily see the widening cracks and increasing losses. I argue that we need to respond and that love and hope form the basis for our responsibility to advocate for the transformative change needed to safeguard and recover nature.
Environmental crises, such as wildfires, can cause major losses of human life, infrastructure, biodiversity, and cultural values. In many such situations, incident controllers must make fateful ...choices about what to protect—and hence what to abandon. With an online representative survey of >2000 adult Australians, we investigated social attitudes to this dilemma. We used best–worst scaling to assess preferences across a set of 11 assets representing human life, infrastructure, biodiversity, and cultural values. Survey respondents overwhelmingly prioritized a single human life (best–worst score of 6647 out of possible score ranging from −10695 to 10695), even if that choice resulted in extinction of other species. Inanimate (replaceable) objects were accorded lowest priority (best–worst scores of −4655 for a shed and −3242 for a house). Among biodiversity assets, respondents prioritized protecting a population of the iconic koala (Phascolarctos cinereus) (best–worst score of 1913) ahead of preventing the extinction of a snail (score −329) and a plant species (−226). These results variably support current policy in that they emphasize the importance the community places on protection of human life, but results diverged from conventional practice in rating some biodiversity assets ahead of infrastructure. The preference for protecting a population of koalas ahead of action taken to prevent the extinction of an invertebrate and plant species corroborates previous research reporting biases in the way people value nature. If noncharismatic species are not to be treated as expendable, then the case for preventing their extinction needs to be better made to the community. Given the increasing global incidence of high‐severity wildfires, further sampling of societal preferences among diverse asset types is needed to inform planning, policy, and practice relating to wildfire. Other preemptive targeted management actions (such as translocations) are needed to conserve biodiversity, especially noniconic species, likely to be imperiled by catastrophic events.
Valoración social de la biodiversidad en relación con otros tipos de activos en riesgo durante los incendios
Resumen
Las crisis ambientales, como los incendios, pueden causar pérdidas mayores de infraestructura, vida humana, biodiversidad y valores culturales. En muchas de estas situaciones, quienes controlan el incidente deben tomar decisiones fatídicas sobre qué proteger y, por lo tanto, qué abandonar. Aplicamos en línea una encuesta representativa a más de 2000 australianos adultos para investigar las actitudes sociales ante este dilema. Usamos la escala de mejor‐peor para valorar las preferencias en once activos que representaban la vida humana, infraestructura, biodiversidad y valores culturales. Los encuestados priorizaron de manera abrumadora la vida humana (puntaje de 6647 en la escala de mejor‐peor con un puntaje posible entre ‐10695 y 10695), incluso si esto implicaba la extinción de otras especies. Los objetos inanimados (reemplazables) fueron los de menor prioridad (puntaje de ‐4655 para una choza y ‐3242 para una casa). Entre los activos de biodiversidad, los encuestados priorizaron la protección de una población del icónico koala (Phascolarctos cinereus) (puntaje de 1913) por encima de la extinción de una especie de caracol (‐329) y una de planta (‐226). Estos resultados respaldan de forma variada la política actual pues resaltan la importancia que la comunidad le da a la protección de la vida humana, pero los resultados discreparon de la práctica convencional al puntear a algunos activos de la biodiversidad por encima de la infraestructura. La preferencia por proteger la población de koalas por encima de evitar la extinción de una especie invertebrada y una especie botánica corrobora las investigaciones anteriores que reportan un sesgo en la forma en la que la población valora la naturaleza. Si queremos que las especies carismáticas no sean tratadas como prescindibles, entonces se le debe plantear de mejor manera a la población el caso para prevenir su extinción. Con el aumento en la incidencia mundial de incendios de gravedad, se necesita un mayor muestreo de las preferencias sociales por los diferentes tipos de activos para guiar la planeación, políticas y prácticas en relación con los incendios. Se requieren otras acciones de manejo preventivo enfocado (como las reubicaciones) para conservar la biodiversidad con probabilidad de estar en peligro durante eventos catastróficos, especialmente las especies que no son icónicas.
As with most governments worldwide, Australian governments list threatened species and proffer commitments to recovering them. Yet most of Australia's imperiled species continue to decline or go ...extinct and a contributing cause is inadequate investment in conservation management. However, this has been difficult to evaluate because the extent of funding committed to such recovery in Australia, like in many nations, is opaque. Here, by collating disparate published budget figures of Australian governments, we show that annual spending on targeted threatened species recovery is around U.S.$92m (AU$122m) which is around one tenth of that spent by the U.S. endangered species recovery program, and about 15% of what is needed to avoid extinctions and recover threatened species. Our approach to estimating funding needs for species recovery could be applied in any jurisdiction and could be scaled up to calculate what is needed to achieve international goals for ending the species extinction crisis.
Every year large proportions of northern Australia's tropical savanna landscapes are burnt, resulting in high fire frequencies and short intervals between fires. The dominant fire management paradigm ...in these regions is the use of low‐intensity prescribed fire early in the dry season, to reduce the incidence of higher‐intensity, more extensive wildfire later in the year. This use of frequent prescribed fire to mitigate against high‐intensity wildfire has parallels with fire management in temperate forests of southern Australia. However, unlike in southern Australia, the ecological implications of high fire frequency have received little attention in the north. CSIRO and collaborators recently completed a landscape‐scale fire experiment at Kapalga in Kakadu National Park, Northern Territory, Australia, and here we provide a synthesis of the effects of experimental fire regimes on biodiversity, with particular consideration of fire frequency and, more specifically, time‐since‐fire. Two recurring themes emerged from Kapalga. First, much of the savanna biota is remarkably resilient to fire, even of high intensity. Over the 5‐year experimental period, the abundance of most invertebrate groups remained unaffected by fire treatment, as did the abundance of most vertebrate species, and we were unable to detect any effect of fire on floristic composition of the grass‐layer. Riparian vegetation and associated stream biota, as well as small mammals, were notable exceptions to this general resilience. Second, the occurrence of fire, independent of its intensity, was often the major factor influencing fire‐sensitive species. This was especially the case for extinction‐prone small mammals, which have suffered serious population declines across northern Australia in recent decades. Results from Kapalga indicate that key components of the savanna biota of northern Australia favour habitat that has remained unburnt for at least several years. This raises a serious conservation concern, given that very little relatively long unburnt habitat currently occurs in conservation reserves, with most sites being burnt at least once every 2 years. We propose a conservation objective of increasing the area that remains relatively long unburnt. This could be achieved either by reducing the proportion of the landscape burnt each year, or by setting prescribed fires more strategically. The provision of appropriately long unburnt habitat is a conservation challenge for Australia's tropical savanna landscapes, just as it is for its temperate forests.
Small mammal species are declining across northern Australia. Predation by feral cats Felis sylvestris catus is one hypothesised cause. Most evidence of cat impacts on native prey comes from islands, ...where cat densities are often high, but cats typically occur at low densities on mainland Australia. We conducted a field experiment to measure the effect of predation by low‐density cat populations on the demography of a native small mammal. We established two 12·5‐ha enclosures in tropical savanna in the Northern Territory. Each enclosure was divided in half, with cats allowed access to one half but not the other. We introduced about 20 individuals of a native rodent, Rattus villosissimus, into each of the four compartments (two enclosures × two predator‐access treatments). We monitored rat demography by mark‐recapture analysis and radiotracking, and predator incursions by camera surveillance and track and scat searches. Rat populations persisted over the duration of the study (18 months) in the predator‐proof treatment, where we detected no predator incursions, but declined to extinction in both predator‐accessible compartments. In one case, cat incursions were frequently detected and the rat population was rapidly extirpated (<3 months); in the other, cat incursions were infrequent, and the population declined more gradually (c. 16 months) due to low recruitment. We detected no incursions by dingoes Canis dingo, the other mammalian predator in the area. Synthesis and applications. This is the first study to provide direct evidence that cats are capable of extirpating small mammals in a continental setting, in spite of their low population densities. This finding supports the hypothesis that predation by feral cats is contributing to declines of small mammals in northern Australia. The conservation management of native small mammals in northern Australia may require intensive control of cat populations, including large cat‐free enclosures.
Rock-wallabies (
Petrogale
spp.) are one of Australia’s most speciose genera of mammals, irregularly distributed across much of the continent and its offshore islands. The 25 taxa in the genus ...Petrogale (17 species and 8 subspecies) have specialised ecological requirements that render them vulnerable to numerous threats. Many rock-wallaby populations have declined severely, and most species and subspecies are experiencing ongoing declines in population size, distribution and their conservation status. Despite an explicit recognition of the need for conservation management, some species are not monitored and a consensus on the most appropriate methods for ongoing population monitoring has proven elusive. We reviewed the available literature to understand the conservation issues and threats most relevant to
Petrogale
spp. We also reviewed rock-wallaby monitoring programs with the aim of identifying which are most informative of population trends, and most suitable for guiding better management responses. Major threats to rock-wallabies include predation by introduced cats and foxes, competition from introduced herbivores and overabundant native herbivores, changed fire regimes and loss of genetic diversity. There are synergisms that exacerbate these threats. While live-trapping gives comprehensive population data, camera traps have proven popular for collecting data over long periods, have minimal animal welfare impacts, and can simultaneously collect data on some significant co-occurring threats (feral predators and herbivores). A variety of rock-wallaby monitoring programs are current in Australia, but few adequately provide the range of data necessary for informed conservation. Monitoring programs should consider incorporating multiple methods to ensure the range of information necessary for successfully conserving rock-wallabies is obtained.
We studied the response of vegetation and vertebrate assemblages to fire and grazing, and their interacting effects, in Eucalyptus woodland in north-eastern Australia. In this vegetation type, many ...pastures remain free of cattle grazing due to the occurrence of a native shrub poisonous to livestock. Vegetation (floristic data and 22 habitat variables) and vertebrate fauna (birds, mammals, reptiles) were sampled in 29 standardized 50 × 50-m quadrats in the 2001 wet season, representing four treatments: sites burnt recently (within 2 y) and grazed by cattle (4–8 ha per livestock unit); sites unburnt (last burnt >2 y ago) and grazed; sites burnt recently and ungrazed; and unburnt and ungrazed sites. Fire and grazing had a significant influence on vegetation: both grazing and fire reduced ground cover (fire in grazed sites 51–23%, fire in ungrazed sites 68–39%) and increased the cover of forbs (8% in burnt and grazed sites, 3% if ungrazed) and tussock grasses (20% in grazed and unburnt sites and 5% when ungrazed). Grazing caused a shift in floristic composition from the perennial hummock grass Trioda pungens to tussock grasses (e.g. Aristida spp., Enneapogon spp.), forbs (e.g. Phyllanthus spp.) and shrubs (e.g. Acacia spp.). Of the vertebrate groups, birds responded more to fire effects (9 species), reptiles to grazing effects (6 species) and mammals to the interaction (2 species). Species reacted to increases in bare ground (e.g. crested pigeon Ocyphaps lophotes, hooded robin Melanodryas cucullatus, Ctenophorus nuchalis) and to the dominant ground cover (e.g. Ctenotus pantherinus) or change in vegetation architecture (e.g. singing honeyeater Lichenostomus virescens, variegated fairy-wren Malurus lamberti). The clearest example of an interacting effect was the cycle of complementary dominance between the rodents Pseudomys delicatulus and P. desertor, the latter's post-fire recovery becoming more muted in sites where cattle grazed (modelled time for population recovery twice as long as in ungrazed sites).
Strategies for mitigating climate change through altered land management practices can provide win–win outcomes for the environment and the economy. Emissions trading for greenhouse gas (GHG) ...abatement in Australia's remote, fire‐prone, and sparsely populated tropical savannas provides a financial incentive for intensive fire management that aims to reduce fire frequency, severity, and extent, and it supports important social, economic, and land management opportunities for remote communities, conservation agencies, and pastoralists. These programs now cover >20% of Australia's 1.9 million km2 tropical savanna biome, encompassing areas of globally significant biodiversity value. A common assertion is that by reducing the frequency, severity, and extent of fires for GHG abatement, these programs provide biodiversity co‐benefits. However, such biodiversity benefits have been assumed rather than demonstrated. Much better accounting of how biodiversity is responding to changed fire management is required to ensure that there are no unintended outcomes for biodiversity (bioperversity), and that biodiversity co‐benefits are maximized. Such accounting could underpin the earning of formal biodiversity credits from improved fire management, and will go a long way to understanding and improving the biodiversity outcomes of savanna fire management.
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