Defining success in bushfire management: critical moments in the 2012-13 ACT bushfire season

The 2012-13 Australian Capital Territory fire season saw no loss of life, no major property loss and minimal environmental damage. It was therefore successful according to the main aims of bushfire management. This outcome hinged on a few critical moments when, due to a combination of strategy and good fortune, things went right. This case study demonstrates how influential chance can be in determining the outcome of bushfires and this in turn begs the question: should agencies be held responsible for factors that are beyond human control? It is proposed that holding agencies responsible for outcomes that are not entirely within their control, acts to reduce community resilience because it implicitly removes the onus on individuals to take personal responsibility; a vital component for good outcomes

Plasmonic Metasurface Resonators to Enhance Terahertz Magnetic Fields for High-Frequency Electron Paramagnetic Resonance

Nanoscale magnetic systems play a decisive role in areas ranging from biology to spintronics. Although, in principle, THz electron paramagnetic resonance (EPR) provides high-resolution access to their properties, lack of sensitivity has precluded realizing this potential. To resolve this issue, the principle of plasmonic enhancement of electromagnetic fields that is used in electric dipole spectroscopies with great success is exploited, and a new type of resonators for the enhancement of THz magnetic fields in a microscopic volume is proposed. A resonator composed of an array of diabolo antennas with a back-reflecting mirror is designed and fabricated. Simulations and THz EPR measurements demonstrate a 30-fold signal increase for thin film samples. This enhancement factor increases to a theoretical value of 7500 for samples confined to the active region of the antennas. These findings open the door to the elucidation of fundamental processes in nanoscale samples, including junctions in spintronic devices or biological membranes

The response of birds to the fire regimes of mulga woodlands in central Australia

Made available by the Northern Territory Library via the Publications (Legal Deposit) Act 2004 (NT)."In this thesis I investigate the key assumptions of the fire mosaic hypothesis using a model system, the mulga woodland/mulga bird community of central Australia. Mulga woodland is an ideal model system for this question because it is structurally and floristically simple, yet supports a rich avifauna. I tested how avian diversity (variety and number) was influenced by 1) time-since-fire; 2) patch size; and 3) the boundary between burnt and unburnt mulga woodland (pyric edge)." - AbstractAbstract -- The fire mosaic hypothesis -- Fire and birds -- Background to methods -- The experimental landscape -- Habitat assessment -- Time-since-fire -- Patch size effect -- Edge effect -- The fire mosaic hypothesis and biodiversity -- References -- Appendix 1-2Thesis (Ph.D.) -- Australian National University, 2008

The Effect of Patch Area on Birds in Central Australian Mulga (Acacia aneura) Woodland of Different Times-since-fire

It is often assumed that a fine-scaled mosaic of different times-since-fire supports greater biodiversity than a coarsescaled mosaic - the fire mosaic hypothesis. A potential mechanism of the fire mosaic hypothesis is the effect of area on species divers

Communicating about danger: urgency alarm calling in a bird

Vertebrate flee alarm calls can provide information about the type of predator, and some mammalian alarm calls also appear to communicate the degree of danger and therefore urgency of escape. However, because predators are usually rare, it has proved difficult to obtain observations differing only in the degree of danger, or to record sufficient naturally provoked alarm calls for fully replicated playback experiments. In this study, we took advantage of a system in which the major aerial predator was common, allowing repeated, matched observations of natural interactions between predator and prey, combined with a fully replicated playback experiment. We found that the aerial trill alarm call of the white-browed scrubwren, Sericornis frontalis, varied according to the distance from the suddenly appearing predator: the closer the predator, the greater the number of elements in the call and the higher their minimum frequency (pitch). Playback experiments showed that multi-element alarm calls prompted a more urgent response, including immediate fleeing to cover. Furthermore, the response was graded, such that an alarm with more elements provoked a more urgent response. Our study therefore isolated the effect of predator distance on alarm call design, and showed that individuals respond appropriately to calls in the absence of any other cues. To our knowledge, this is the most explicit demonstration that avian flee alarm calls can convey urgency

The effect of fire on birds of mulga woodland in arid central Australia

The principal ecosystem driver in arid Australia is unpredictable rainfall, but it is hypothesised that fire also plays an important role in determining the distribution of animals. We investigated the effect of fire on birds in mulga (Acacia aneura) woodland in the central Australian arid zone. The study was conducted at UluruKata Tjuta National Park using 63 sites classified into one of three time-since-fire classes: burnt 2002; burnt 1976; and long-unburnt. Birds were sampled in the winter and spring of 2005 and 2006 and vegetation structure was measured at all sites. Vegetation structure varied with time-since-fire. The burnt 2002 treatment was an early seral stage of mulga woodland and effectively a grassland. The burnt 1976 and long-unburnt treatments were both woodland, but the long-unburnt treatment had greater canopy cover and height. The bird community in the burnt 2002 treatment was characterised by granivores, whereas that in the burnt 1976 and long-unburnt treatments was characterised by foliar insectivores. All species showed monotonic responses to time-since-fire (i.e. none were at significantly highest density in the burnt 1976 treatment). Fire in mulga woodland changed the vegetation structure and consequently also changed the composition of the bird communities

Bird's Response to Revegetation of Different Structure and Floristics - Are "Restoration Plantings" Restoring Bird Communities?

Revegetation plantings have been established throughout the world to mitigate the effects of clearing, including loss of faunal habitat. Revegetation plantings can differ substantially in structural complexity and plant diversity, with potentially differing habitat qualities for fauna. We studied bird occurrence in revegetation of different complexity and floristics in southern Australia. We assessed bird species richness and composition in remnant forest and cleared agricultural land as reference points, and in two types of plantings differing in structure and floristics-(1) "woodlot plantings" composed of native trees only and (2) "ecological plantings" composed of many species of local trees, shrubs and understorey. By approximately 20 years of age, both types of plantings had a similar bird species richness to that in remnants. Bird species richness was greater in ecological plantings than woodlot plantings. Species composition also differed. Ecological plantings contained a shrub-associated bird assemblage, whereas woodlot plantings were dominated by generalist bird species. Remnants contained a unique bird assemblage, which were not found in either of the two types of plantings, suggesting that plantings are not a viable replacement of remnant vegetation over this time period. Bird species richness responded positively to structural complexity, but not to floristic richness. Bird species richness was greater in plantings that were older, in riparian locations, and where weed cover was lower. We conclude that plantings in general can provide habitat for many species of birds, and that structurally complex ecological plantings in particular will provide unique and valuable additional habitat for birds

Comparison of contrasting optical and LiDAR fire severity remote sensing methods in a heterogeneous forested landscape in south-eastern Australia

Spectral indices derived from satellite optical remote sensing data have typically been used for fire severity estimation, although other remote sensing systems such as Light Detection and Ranging (LiDAR) are increasingly applied. Despite a multitude of remotely sensed fire severity estimation methods, comparisons of method performance are few. Insights into the merits and limitations of remotely sensed fire severity methods help develop appropriate spatial tools for the management of fire-affected areas. We evaluated the performance of seven passive (optical) and active (LiDAR) remotely sensed fire severity estimation methods in classifying and explaining variation in a field-estimated modified Composite Burn Index (MCBI) for a recent large wildfire in south-eastern Australia. Our evaluation included three commonly applied indices; the differenced Normalized Burn Ratio (dNBR), Relative dNBR (RdNBR) and Relative Burn Ratio (RBR). We compared these NBR indices against two recently proposed fire severity estimation methods that have not previously been evaluated with CBI field data–the Vegetation Structure Perpendicular Index (VSPI) spectral index and the LiDAR point cloud-derived Profile Area Change (PAC), along with experimental relativized forms of these indices (RVSPI and RPAC, respectively). The RVSPI (κ = 0.47) demonstrated similar overall classification accuracy (N classes = 4) to the PAC (κ = 0.48), however both indices had lower classification accuracy than the dNBR (κ = 0.59), RdNBR (κ = 0.59) and RBR (κ = 0.61). The VSPI and PAC were unable to accurately represent non-structural changes caused by lower severity fire. Application of these optical and LiDAR indices should consider their discussed limitations in relation to the objectives of their application