40 research outputs found

    Modelling the spatial extent of post‐fire sedimentation threat to estimate the impacts of fire on waterways and aquatic species

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    Aim Fires can severely impact aquatic fauna, especially when attributes of soil, topography, fire severity and post-fire rainfall interact to cause substantial sedimentation. Such events can cause immediate mortality and longer-term changes in food resources and habitat structure. Approaches for estimating fire impacts on terrestrial species (e.g. intersecting fire extent with species distributions) are inappropriate for aquatic species as sedimentation can carry well downstream of the fire extent, and occur long after fire. Here, we develop an approach for estimating the spatial extent of fire impacts for aquatic systems, across multiple catchments. Location Southern Australian bioregions affected by the fires in 2019–2020 that burned >10 million ha of temperate and subtropical forests. Methods We integrated an existing soil erosion model with fire severity mapping and rainfall data to estimate the spatial extent of post-fire sedimentation threat in waterways and in basins and the potential exposure of aquatic species to this threat. We validated the model against field observations of sedimentation events after the 2019–20 fires. Results While fires overlapped with ~27,643 km of waterways, post-fire sedimentation events potentially occurred across ~40,449 km. In total, 55% (n = 85) of 154 basins in the study region may have experienced substantial post-fire sedimentation. Ten species—including six Critically Endangered—were threatened by post-fire sedimentation events across 100% of their range. The model increased the estimates for potential impact, compared to considering fire extent alone, for >80% of aquatic species. Some species had distributions that did not overlap with the fire extent, but that were entirely exposed to post-fire sedimentation threat. Conclusions Compared with estimating the overlap of fire extent with species' ranges, our model improves estimates of fire-related threats to aquatic fauna by capturing the complexities of fire impacts on hydrological systems. The model provides a method for quickly estimating post-fire sedimentation threat after future fires in any fire-prone region, thus potentially improving conservation assessments and informing emergency management interventions

    Dark resonances for ground state transfer of molecular quantum gases

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    One possible way to produce ultracold, high-phase-space-density quantum gases of molecules in the rovibronic ground state is given by molecule association from quantum-degenerate atomic gases on a Feshbach resonance and subsequent coherent optical multi-photon transfer into the rovibronic ground state. In ultracold samples of Cs_2 molecules, we observe two-photon dark resonances that connect the intermediate rovibrational level |v=73,J=2> with the rovibrational ground state |v=0,J=0> of the singlet X1Σg+X^1\Sigma_g^+ ground state potential. For precise dark resonance spectroscopy we exploit the fact that it is possible to efficiently populate the level |v=73,J=2> by two-photon transfer from the dissociation threshold with the stimulated Raman adiabatic passage (STIRAP) technique. We find that at least one of the two-photon resonances is sufficiently strong to allow future implementation of coherent STIRAP transfer of a molecular quantum gas to the rovibrational ground state |v=0,J=0>.Comment: 7 pages, 4 figure

    Restoring habitat for fire-impacted species’ across degraded Australian landscapes

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    In the summer of 2019–2020, southern Australia experienced the largest fires on record, detrimentally impacting the habitat of native species, many of which were already threatened by past and current anthropogenic land use. A large-scale restoration effort to improve degraded species habitat would provide fire-affected species with the chance to recover and persist in burnt and unburnt habitat. To facilitate this, decision-makers require information on priority species needs for restoration intervention, the suite of potential restoration interventions, and the priority locations for applying these interventions. We prioritize actions in areas where restoration would most likely provide cost-effective benefits to priority species (defined by each species proportion of habitat burned, threat status, and vulnerability to fires), by integrating current and future species habitat suitability maps with spatially modelled costs of restoration interventions such as replanting, removing invasive species, and implementing ecologically appropriate fire management. We show that restoring the top ∼69% (112 million hectares) of the study region (current and future distributions of priority species) accounts for, on average, 95% of current and future habitat for every priority species and costs ∼AUD73billionyr1(AUD73 billion yr−1 (AUD650 hectare−1 yr−1 ) annualized over 30 years. This effort would include restoration actions over 6 million hectares of fire-impacted habitat, costing ∼AUD8.8billion/year.Largescalerestorationeffortsareoftencostlybutcanhavesignificantsocietalcobenefitsbeyondbiodiversityconservation.Wealsoshowthatupto291MtCO2(150MtDM)ofcarboncouldbesequesteredbyrestorationefforts,resultinginapproximatelyAUD8.8 billion/year. Large scale restoration efforts are often costly but can have significant societal co-benefits beyond biodiversity conservation. We also show that up to 291 MtCO2 (∼150 Mt DM) of carbon could be sequestered by restoration efforts, resulting in approximately AUD253 million yr−1 in carbon market revenue if all carbon was remunerated. Our approach highlights the scale, costs, and benefits of targeted restoration activities both inside and outside of the immediate bushfire footprint over vast areas of different land tenures.Michelle Ward, Ayesha Tulloch, Romola Stewart, Hugh P Possingham, Sarah Legge, Rachael V Gallagher, Erin M Graham, Darren Southwell, David Keith, Kingsley Dixon, Chuanji Yong, Josie Carwardine, Tim Cronin, April E Reside, and James E M Watso

    A Classic Textbook

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    Aeronautical Progress, 1914 to 1930

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    A mixed variational formulation for large deformation analysis of plates

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    Saint-Venant Effects in an Orthotropic Beam

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