Detecting new Buffel grass infestations in Australian arid lands: evaluation of methods using high-resolution multispectral imagery and aerial photography

We assess the feasibility of using airborne imagery for Buffel grass detection in Australian arid lands and evaluate four commonly used image classification techniques (visual estimate, manual digitisation, unsupervised classification and normalised difference vegetation index (NDVI) thresholding) for their suitability to this purpose. Colour digital aerial photography captured at approximately 5 cm of ground sample distance (GSD) and four-band (visible–near-infrared) multispectral imagery (25 cm GSD) were acquired (14 February 2012) across overlapping subsets of our study site. In the field, Buffel grass projected cover estimates were collected for quadrates (10 m diameter), which were subsequently used to evaluate the four image classification techniques. Buffel grass was found to be widespread throughout our study site; it was particularly prevalent in riparian land systems and alluvial plains. On hill slopes, Buffel grass was often present in depressions, valleys and crevices of rock outcrops, but the spread appeared to be dependent on soil type and vegetation communities. Visual cover estimates performed best (r(2) 0.39), and pixel-based classifiers (unsupervised classification and NDVI thresholding) performed worst (r(2) 0.21). Manual digitising consistently underrepresented Buffel grass cover compared with field- and image-based visual cover estimates; we did not find the labours of digitising rewarding. Our recommendation for regional documentation of new infestation of Buffel grass is to acquire ultra-high-resolution aerial photography and have a trained observer score cover against visual standards and use the scored sites to interpolate density across the region

Current understanding of the effects of congestion on traffic accidents

Traffic accidents impart both economic and social costs upon communities around the world, hence the desire for accident rates to be reduced. For this reduction to occur, the factors influencing the occurrence of accidents must be understood. The role of congestion in modifying accident risk has been widely studied, but consensus has not been reached, with conflicting results leaving open questions. An inverse relationship between accidents and congestion would imply a benefit of congested conditions for road safety, posing a difficult situation for traffic management. This paper assesses articles that reveal the shape of the relationship between traffic accidents and congestion. We find a positive linear response to dominate the literature. However, studies with higher numbers of statistical units tend to show a U-shaped relationship. This suggests an important role of high spatio-temporal traffic data in understanding factors causing accidents and identifying the combination of real-time conditions which may lead to increased accident risk. Modern advancements in traffic measurement systems provide the ability for real-time alleviation of accident-prone conditions before they can fully develop.Angus Eugene Retallack and Bertram Ostendor

Stripping away sky reflectance, waves and turbulence for benthic mapping: Imaging the seafloor not the surface

This paper presents the results of an airborne experiment using horizontal and vertical polarising filters on a pair of co-mounted 12.8 megapixel Canon 5D digital cameras. These cameras were mounted in the underside camera port of a light aircraft, both cameras inclined at 30 degrees off-nadir. One camera had the polarisation filter oriented vertically and the other oriented horizontally. Forward-looking, overlapping, oblique aerial photography was captured over known seagrass meadows off the Adelaide metropolitan coastline, plus inland urban water bodies. The portrait oriented field of view allowed a progression on the image from near-nadir to beyond the critical Brewster angle of 53 degrees. Results show the removal of sky reflectance, turbulence and wave action on the vertically-oriented filter imagery compared to the horizontally-oriented filter imagery in both clear and turbid waters. For clear waters the removal of sky reflectance, waves and surface turbulence allowed visualisation of the seafloor suitable for benthic mapping in areas of seagrass. However in turbid water the removal of surface effects still did not allow the seafloor to be visualised due to multiple scatter in the body of the water. This method therefore also has application in differentiating clear and turbid waters on oblique photography

The behavioral responses of a nocturnal burrowing marsupial (Lasiorhinus latifrons) to drone flight

The use of drones in wildlife research and management is increasing. Recent evidence has demonstrated the impact of drones on animal behavior, but the response of nocturnal animals to drone flight remains unknown. Utilizing a lightweight commercial drone, the behavioral response of southern hairy-nosed wombats (Lasiorhinus latifrons) to drone flights was observed at Kooloola Station, Swan Reach, South Australia. All wombats flown over during both day and night flights responded behaviorally to the presence of drones. The response differed based on time of day. The most common night-time behavior elicited by drone flight was retreat, compared to stationary alertness behavior observed for daytime drone flights. The behavioral response of the wombats increased as flight altitude decreased. The marked difference of behavior between day and night indicates that this has implications for studies using drones. The behavior observed during flights was altered due to the presence of the drone, and therefore, shrewd study design is important (i.e., acclimation period to drone flight). Considering the sensory adaptations of the target species and how this may impact its behavioral response when flying at night is essential.Taylor Headland, Bertram Ostendorf, David Taggar

A comparison between video and still imagery as a methodology to determine southern hairy-nosed wombat (Lasiorhinus latifrons) burrow occupancy rates

Published: 23 October 2018Broad-scale abundance estimates of the southern hairy-nosed wombat population use a proxy measure based on counting the number of active burrows, which is multiplied by an index of 'wombats/active burrow'. However, the extant indices were calculated in the 1980s, prior to the use of calicivirus to control rabbits, and used invasive monitoring methods which may have affected the results. We hypothesise that the use of video might provide a logistically simple, non-invasive means of calculating updated indices. To this end, motion-activated, infra-red still and video cameras were placed at various distances outside active wombat burrows in the South Australian Murraylands and Eyre Peninsula regions. The captured imagery was inspected to determine how often the burrow was occupied by one or more wombats, and how effective the cameras were at detecting wombat activity. Video data was clearly superior to the still imagery, with more than twice as many burrow occupancies being positively identified (still: 43%). The indices of wombats/active burrow calculated based on video imagery were: Murraylands: 0.43, Eyre Peninsula: 0.42. 1948 false positive videos were recorded, of which 1674 (86%) occurred between noon and sunset.Michael J. Swinbourne, David A. Taggart and Bertram Ostendor

Relative spatial differences in sediment transport in fire-affected agricultural landscapes: A field study

Available online 15 April 2019Fires can considerably increase wind erosion risk in dryland agricultural regions. While wind erosion post-fire has been extensively studied in rangeland and grazing landscapes, limited work has considered post-fire erosion on annual plant communities and annual crops. Here we evaluated the relative spatial differences in patterns of sediment transport between burnt and unburnt crop stubble sites. Following a severe wildfire, we studied the spatio-temporal pattern of aeolian sediment transport with an array of Modified Wilson and Cooke (MWAC) dust samplers on adjacent burnt and unburnt wheat stubble. Sediment collection was conducted during nine weeks over an area of 3 ha. Collection rates were converted to horizontal sediment flux to derive spatial distribution maps and perform statistical analysis. Compared to the unburnt plot, we observed that sediment transport was up to 1000 times higher within the burnt area. This could lead to damages to emerging annual crops sown after the fire if no management strategy was applied. There was only negligible sediment flux in areas with shallow and low-density stubble, which gradually increased with distance from the unburnt area. These results suggest that strips of remaining unburnt stubble could provide a potential benefit to adjacent burnt or bare plots. Patterns of sediment transport were consistent in all sampling periods and were observed at a spatial scale undetectable in wind tunnel studies, indicating that field observations could complement fine-scale experimental studies to assess environmental processes in real-life conditions.Amelie C. Jeanneau, Bertram Ostendorf, Tim Herrman

Seeing seagrasses sidewards: marine angiosperms and the Stokes' polarization parameters

Mapping of marine benthic flora using remote sensing techniques has been used to assess the dynamics of environmental conditions in coastal areas. Mostly studies used panchromatic/colour aerial photography and/or medium resolution multispectral satellite imagery to create time series showing the change of seagrass distribution, as indicator species of environmental conditions. While successful within their project parameters, these studies were limited by conditions at time of image capture, such as sun-glare, turbidity, wave action and low contrast in deeper waters due to absorption and scattering. The use of polarized multispectral imagery has the potential to overcome, or at least reduce these problems such that a finer detail of benthic flora may become visible. This paper explores the theoretical background in the application of polarization for mapping seagrass and other marine benthic flora. It also discusses a possible operational design using a low cost airborne multispectral camera.David Hart, Megan Lewis, Bertram Ostendorf and Paul Darehttp://www.arspc.org/abstract/36.ht

Understanding the spatially variable effects of climate change on rice yield for three ecotypes in Bangladesh, 1981-2010

Climate change will impact on rice food security in many parts of the world, including Bangladesh. Little attention has been given to understanding the impact of climate on rice yield for three main ecotypes (Aus, Aman, and Boro) in different areas of the country. The aim of this paper was to analyse the spatiotemporal dynamics of rice yield and climatic variables and the spatially variable climate effects on rice yield for these ecotypes in Bangladesh during 1981-2010 by employing linear mixed models and generalized linear models. The results demonstrated the substantial spatiotemporal variations of rice yield for all ecotypes across the country. Rice yield for ecotypes was more susceptible to temperature changes than rainfall effects. Modelling of a 1°C temperature increase in the country showed strong regional differences in rice yield for these ecotypes. The study concludes that future temperature changes are likely to change regional rice yield for all ecotypes and hence impact food security. The results have important consequences for food security by indicating the need for appropriate region-specific adaptation measures to reduce rice yield variability in the future. The results show the need to consider spatial differences for policy development to improve food security in Bangladesh

Mr. and Mrs. Lincoln hanging their Christmas wreath on their front door in Springfield, Illinois in 1860

Greeting card from Lincoln Memorial University. Its front features a Lloyd Ostendorf illustration of Abraham Lincoln hanging a wreath on a door with Mary Todd Lincoln. The inside includes a Christmas greeting.https://scholarsjunction.msstate.edu/fvw-artifacts/4389/thumbnail.jp

Abraham Lincoln with Tad and Willie at a Toy Store

Greeting card from Lincoln Memorial University. Its front features a Lloyd Ostendorf illustration of Abraham Lincoln peering through a toy store window with two of his sons. The inside includes a Christmas greeting. Accompanied by an enveloped addressed to Mr. Frank J. Williams.https://scholarsjunction.msstate.edu/fvw-artifacts/4320/thumbnail.jp