Fire management across Australia's fire-prone 1.2 M km2 northern savannas region has been transformed over the past decade supported by the inception of Australia's national regulated emissions ...reduction market in 2012. Today, incentivised fire management is undertaken over a quarter of that entire region, providing a range of socio-cultural, environmental, and economic benefits, including for remote Indigenous (Aboriginal and Torres Strait Islander) communities and enterprises. Building on those advances, here we explore the emissions abatement potential for expanding incentivised fire management opportunities to include a contiguous fire-prone region, extending to monsoonal but annually lower (<600 mm) and more variable rainfall conditions, supporting predominantly shrubby spinifex (Triodia) hummock grasslands characteristic of much of Australia's deserts and semi-arid rangelands. Adapting a standard methodological approach applied previously for assessing savanna emissions parameters, we first describe fire regime and associated climatic attributes for a proposed ∼850,000 km2 lower rainfall (600–350 mm MAR) focal region. Second, based on regional field assessments of seasonal fuel accumulation, combustion, burnt area patchiness, and accountable methane and nitrous oxide Emission Factor parameters, we find that significant emissions abatement is feasible for regional hummock grasslands. This applies specifically for more frequently burnt sites under higher rainfall conditions if substantial early dry season prescribed fire management is undertaken resulting in marked reduction in late dry season wildfires. The proposed Northern Arid Zone (NAZ) focal envelope is substantially under Indigenous land ownership and management, and in addition to reducing emissions impacts associated with recurrent extensive wildfires, development of commercial landscape-scale fire management opportunities would significantly support social, cultural and biodiversity management aspirations as promoted by Indigenous landowners. Combined with existing regulated savanna fire management regions, inclusion of the NAZ under existing legislated abatement methodologies would effectively provide incentivised fire management covering a quarter of Australia's landmass. This could complement an allied (non-carbon) accredited method valuing combined social, cultural and biodiversity outcomes from enhanced fire management of hummock grasslands. Although the management approach has potential application to other international fire-prone savanna grasslands, caution is required to ensure that such practice does not result in irreversible woody encroachment and undesirable habitat change.
•Fire management of Australia’s northern savannas has been transformed by inception of Australia’s national carbon market.•We assess potential of incentivised fire management in <600 mm rainfall conditions supporting arid spinifex grasslands.•Significant emissions abatement is feasible for frequently burnt spinifex grasslands based on standard assessment methods.•Adding an 850,000 km2 northern arid zone would afford incentivised fire management over a quarter of Australia’s landmass.
Tropical savannas are characterized by high primary productivity and high fire frequency, such that much of the carbon captured by vegetation is rapidly returned to the atmosphere. Hence, there have ...been suggestions that management‐driven reductions in savanna fire frequency and/or severity could significantly reduce greenhouse gas emissions and sequester carbon in tree biomass. However, a key knowledge gap is the extent to which savanna tree biomass will respond to modest shifts in fire regimes due to plausible, large‐scale management interventions. Here, we: (1) characterize relationships between the frequency and severity of fires and key demographic rates of savanna trees, based on long‐term observations in vegetation monitoring plots across northern Australia; (2) use these relationships to develop a process‐explicit demographic model describing the effects of fire on savanna tree populations; and (3) use the demographic model to address the question: to what extent is it feasible, through the strategic application of prescribed burning, to increase tree biomass in Australian tropical savannas? Our long‐term tree monitoring dataset included observations of 12,344 tagged trees in 236 plots, monitored for between 3 and 24 years. Analysis of this dataset showed that frequent high‐severity fires significantly reduced savanna tree recruitment, survival, and growth. Our demographic model suggested that: (1) despite the negative effects of frequent high‐severity fires on demographic rates, savanna tree biomass appears to be suppressed by only a relatively small amount by contemporary fire regimes, characterized by a mix of low‐ to high‐severity fires; and (2) plausible, management‐driven reductions in the frequency of high‐severity fires are likely to lead to increases in tree biomass of about 11.0 t DM ha−1 (95% CI: −1.2–20.8) over a century. Accounting for this increase in carbon storage could generate significant carbon credits, worth, on average, three times those generated annually by current greenhouse gas (methane and nitrous oxide) abatement projects, and has the potential to significantly increase the economic viability of fire/carbon projects, thereby promoting ecologically sustainable management of tropical savannas in Australia and elsewhere. This growing industry has the potential to bring much‐needed economic activity to savanna landscapes, without compromising important natural and cultural values.
Tropical savannas are typically highly productive yet fire-prone ecosystems, and it has been suggested that reducing fire frequency in savannas could substantially increase the size of the global ...carbon sink. However, the long-term demographic consequences of modifying fire regimes in savannas are difficult to predict, with the effects of fire on many parameters, such as tree growth rates, poorly understood. Over 10 years, we examined the effects of fire frequency on the growth rates (annual increment of diameter at breast height) of 3075 tagged trees, at 137 locations throughout the mesic savannas of Kakadu, Nitmiluk and Litchfield National Parks, in northern Australia. Frequent fires substantially reduced tree growth rates, with the magnitude of the effect markedly increasing with fire severity. The highest observed frequencies of mild, moderate and severe fires (1.0, 0.8 and 0.4 fires yr⁻¹, respectively) reduced tree growth by 24%, 40% and 66% respectively, relative to unburnt areas. These reductions in tree growth imply reductions in the net primary productivity of trees by between 0.19 t C ha⁻¹ yr⁻¹, in the case of mild fires, and 0.51 t C ha⁻¹ yr⁻¹, in the case of severe fires. Such reductions are relatively large, given that net biome productivity (carbon sequestration potential) of these savannas is estimated to be just 1-2 t C ha⁻¹ yr⁻¹. Our results suggest that current models of savanna tree demography, that do not account for a relationship between severe fire frequency and tree growth rate, are likely to underestimate the long-term negative effects of frequent severe fires on tree populations. Additionally, the negative impact of frequent severe fires on carbon sequestration rates may have been underestimated; reducing fire frequencies in savannas may increase carbon sequestration to a greater extent than previously thought.
Aim: Comparative analyses of fire regimes at large geographical scales can potentially identify ecological and climatic controls of fire. Here we describe Australia's broad fire regimes, and explore ...interrelationships and trade-offs between fire regime components. We postulate that fire regime patterns will be governed by trade-offs between moisture, productivity, fire frequency and fire intensity. Location: Australia. Methods: We reclassified a vegetation map of Australia, defining classes based on typical fuel and fire types. Classes were intersected with a climate classification to derive a map of 'fire regime niches'. Using expert elicitation and a literature search, we validated each niche and characterized typical and extreme fire intensities and return intervals. Satellite-derived active fire detections were used to determine seasonal patterns of fire activity. Results: Fire regime characteristics are closely related to the latitudinal gradient in summer monsoon activity. Frequent low-intensity fires occur in the monsoonal north, and infrequent, high-intensity fires in the temperate south, demonstrating a trade-off between frequency and intensity: that is, very high-intensity fires are only associated with very low-frequency fire regimes in the high biomass eucalypt forests of southern Australia. While these forests occasionally experience extremely intense fires (> 50,000 kW m -1 ), such regimes are exceptional, with most of the continent dominated by grass fuels, typically burning with lower intensity (< 5000 kW m -1 ). Main conclusions: Australia's fire regimes exhibit a coherent pattern of frequent, grass-fuelled fires in many differing vegetation types. While eucalypts are a quintessential Australian entity, their contribution as a dominant driver of high-intensity fire regimes, via their litter and bark fuels, is restricted to the forests of the continent's southern and eastern extremities. Our analysis suggests that the foremost driver of fire regimes at the continental scale is not productivity, as postulated conceptually, but the latitudinal gradient in summer monsoon rainfall activity.
Human vestibular processing involves distributed networks of cortical and subcortical regions which perform sensory and multimodal integrative functions. These functional hubs are also interconnected ...with areas subserving cognitive, affective, and body-representative domains. Analysis of these diverse components of the vestibular and vestibular-associated networks, and synthesis of their holistic functioning, is therefore vital to our understanding of the genesis of vestibular dysfunctions and aid treatment development. Novel neuroimaging methodologies, including functional and structural connectivity analyses, have provided important contributions in this area, but often require the use of atlases which are comprised of well-defined a priori regions of interest. Investigating vestibular dysfunction requires a more detailed atlas that encompasses cortical, subcortical, cerebellar, and brainstem regions. The present paper represents an effort to establish a compilation of existing, peer-reviewed brain atlases which collectively afford comprehensive coverage of these regions while explicitly focusing on vestibular substrates. It is expected that this compilation will be iteratively improved with additional contributions from researchers in the field.
Value of long-term ecological studies LINDENMAYER, DAVID B.; LIKENS, GENE E.; ANDERSEN, ALAN ...
Austral ecology,
November 2012, Letnik:
37, Številka:
7
Journal Article
Recenzirano
Long‐term ecological studies are critical for providing key insights in ecology, environmental change, natural resource management and biodiversity conservation. In this paper, we briefly discuss ...five key values of such studies. These are: (1) quantifying ecological responses to drivers of ecosystem change; (2) understanding complex ecosystem processes that occur over prolonged periods; (3) providing core ecological data that may be used to develop theoretical ecological models and to parameterize and validate simulation models; (4) acting as platforms for collaborative studies, thus promoting multidisciplinary research; and (5) providing data and understanding at scales relevant to management, and hence critically supporting evidence‐based policy, decision making and the management of ecosystems. We suggest that the ecological research community needs to put higher priority on communicating the benefits of long‐term ecological studies to resource managers, policy makers and the general public. Long‐term research will be especially important for tackling large‐scale emerging problems confronting humanity such as resource management for a rapidly increasing human population, mass species extinction, and climate change detection, mitigation and adaptation. While some ecologically relevant, long‐term data sets are now becoming more generally available, these are exceptions. This deficiency occurs because ecological studies can be difficult to maintain for long periods as they exceed the length of government administrations and funding cycles. We argue that the ecological research community will need to coordinate ongoing efforts in an open and collaborative way, to ensure that discoverable long‐term ecological studies do not become a long‐term deficiency. It is important to maintain publishing outlets for empirical field‐based ecology, while simultaneously developing new systems of recognition that reward ecologists for the use and collaborative sharing of their long‐term data sets. Funding schemes must be re‐crafted to emphasize collaborative partnerships between field‐based ecologists, theoreticians and modellers, and to provide financial support that is committed over commensurate time frames.
Convergent clinical and neuroimaging evidence suggests that higher vestibular function is subserved by a distributed network including visuospatial, cognitive–affective, proprioceptive, and ...integrative brain regions. Clinical vestibular syndromes may perturb this network, resulting in deficits across a variety of functional domains. Here, we leverage structural and functional neuroimaging to characterize this extended network in healthy control participants and patients with post‐concussive vestibular dysfunction (PCVD). Then, 27 healthy control subjects (15 females) and 18 patients with subacute PCVD (12 female) were selected for participation. Eighty‐two regions of interest (network nodes) were identified based on previous publications, group‐wise differences in BOLD signal amplitude and connectivity, and multivariate pattern analysis on affective tests. Group‐specific “core” networks, as well as a “consensus” network comprised of connections common to all participants, were then generated based on probabilistic tractography and functional connectivity between the 82 nodes and subjected to analyses of node centrality and community structure. Whereas the consensus network was comprised of affective, integrative, and vestibular nodes, PCVD participants exhibited diminished integration and centrality among vestibular and affective nodes and increased centrality of visual, supplementary motor, and frontal and cingulate eye field nodes. Clinical outcomes, derived from dynamic posturography, were associated with approximately 62% of all connections but best predicted by amygdalar, prefrontal, and cingulate connectivity. No group‐wise differences in diffusion metrics or tractography were noted. These findings indicate that cognitive, affective, and proprioceptive substrates contribute to vestibular processing and performance and highlight the need to consider these domains during clinical diagnosis and treatment planning.
Convergent clinical and neuroimaging evidence suggests that higher vestibular function is subserved by a distributed network including visuospatial, cognitive–affective, proprioceptive, and integrative brain regions. In this article, we leverage structural and functional neuroimaging to characterize an extended vestibular‐cognitive network in twenty‐seven healthy control participants and eighteen patients with post‐concussive vestibular dysfunction (PCVD), determine commonalities between control and PCVD patients as a “consensus” network, and describe network differences corresponding to clinical outcomes.
Aim Fire is a key agent in savanna systems, yet the capacity to predict fine‐grained population phenomena under variable fire regime conditions at landscape scales is a daunting challenge. Given ...mounting evidence for significant impacts of fire on vulnerable biodiversity elements in north Australian savannas over recent decades, we assess: (1) the trajectory of fire‐sensitive vegetation elements within a particularly biodiverse savanna mosaic based on long‐term monitoring and spatial modelling; (2) the broader implications for northern Australia; and (3) the applicability of the methodological approach to other fire‐prone settings. Location Arnhem Plateau, northern Australia. Methods We apply data from long‐term vegetation monitoring plots included within Kakadu National Park to derive statistical models describing the responses of structure and floristic attributes to 15 years of ambient (non‐experimental) fire regime treatments. For a broader 28,000 km2 region, we apply significant models to spatial assessment of the effects of modern fire regimes (1995–2009) on diagnostic closed forest, savanna and shrubland heath attributes. Results Significant models included the effects of severe fires on large stems of the closed forest dominant Allosyncarpia ternata, stem densities of the widespread savanna coniferous obligate seeder Callitris intratropica, and fire frequency and related fire interval parameters on numbers of obligate seeder taxa characteristic of shrubland heaths. No significant relationships were observed between fire regime and eucalypt and non‐eucalypt adult tree components of savanna. Spatial application of significant models illustrates that more than half of the regional closed forest perimeters, savanna and shrubland habitats experienced deleterious fire regimes over the study period, except in very dissected terrain. Main conclusions While north Australia’s relatively unmodified mesic savannas may appear structurally intact and healthy, this study provides compelling evidence that fire‐sensitive vegetation elements embedded within the savanna mosaic are in decline under present‐day fire regimes. These observations have broader implications for analogous savanna mosaics across northern Australia, and support complementary findings of the contributory role of fire regimes in the demise of small mammal fauna. The methodological approach has application in other fire‐prone settings, but is reliant on significant long‐term infrastructure resourcing.
1. There are concerns that frequent intense fires are reducing biodiversity on the Arnhem Plateau within Kakadu National Park, northern Australia. Since the 1980s, prescribed burning in the early dry ...season has aimed to reduce the extent of late dry season wildfires. A programme of more strategic prescribed burning has been undertaken since 2007, aiming to increase intervals between fires affecting heathland and rain forest communities. 2. We assess the effectiveness of prescribed burning in Kakadu's Stone Country using a Landsat satellite-derived fire history (1980-2011), in terms of achieving 'tolerable fire intervals' for dominant plant communities. 3. Our analysis indicates that fire regimes have become substantially more favourable for biodiversity since the early 1980s. Although annual extent of burning has remained unchanged, two significant changes in fire regimes have occurred over the long term: (i) a switch from late dry season dominance to early dry season dominance and (ii) an increase in the abundance of long-unburnt vegetation, both of which are likely to benefit biodiversity. Demonstrating the statistical significance of changes associated with recent, more strategic fire management (2007-2011) is limited by the short duration of this management approach, although there is evidence of increasing abundance of long-unburnt vegetation during this time. 4. The view that the Arnhem Plateau's fire regimes are increasingly driving biodiversity loss (due to frequent late dry season wildfires) is erroneous; they are in a more benign state now than at any time over the last three decades, most likely due to extensive use of prescribed burning. 5. Synthesis and applications. In highly fire-prone landscapes, such as savannas, prescribed burning can be an effective means of: (i) bringing forward peak fire activity to the time of year when fire conditions are relatively mild and (ii) increasing abundance of long-unburnt vegetation. These changes are likely to favour persistence of a range of fire-sensitive communities. Our case study supports the strategic use of prescribed burning to protect fire-sensitive biota within highly fire-prone landscapes throughout the world.
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