School of Environmental and Rural Science
Permanent URI for this collectionhttps://hdl.handle.net/1959.11/26200
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Browsing School of Environmental and Rural Science by Department "Faculty of Science, Agriculture, Business and Law"
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Journal ArticlePublication A Brief Report on the 2.4-Year Test-Retest Agreement of Morning Cortisol and Anxiety in Boys with Autism Spectrum Disorder(Springer New York LLC, 2019-02-15); ; ; ; Children with Autism Spectrum Disorder (ASD) also often suffer from elevated stress and anxiety. These states can be measured via reports of behaviour (from self or others) or from physiological measures of stress, including the symptoms of Generalised Anxiety Disorder (GAD) and salivary cortisol, respectively. The use of these measures assumes a degree of reliability over time so that data from a specific period may be generalised to other periods. To measure the test-retest reliability of salivary cortisol and self-ratings of GAD in 27 high-functioning boys with ASD (M age = 12.1 yr., SD = 2.8 yr), samples were collected a mean of 2.4 yr. (SD = 0.5 yr) apart and analysed to test for the presence of a significant correlation within each variable over time. Results indicated that, although the concentrations of salivary cortisol increased over the period of the study, there was a significant correlation between the two measures of cortisol. GAD scores also showed a significant correlation over the period of the study. These findings suggest that both GAD and salivary cortisol data collected from boys with ASD may be reasonably inferred to represent fairly stable phenomena over time in research and clinical settings.1899 5 - Some of the metrics are blocked by yourconsent settings
Publication Open AccessConference PublicationField validation of a Species Distribution Model for the central Evolutionarily Significant Unit of the brush-tailed rock-wallaby through aerial surveys(Ecological Society of Australia and the Society for Conservation Biology Oceania (ESA-SCBO), 2022); ;Hook, Lauren ;Sharp, Jess ;Forge, Trent; ; Ashworth, DeborahUnderstanding the distribution of threatened species is key to informing their conservation. Species Distribution Modelling (SDM) is used for a wide range of conservation purposes, and can identify areas of suitable habitat and guide targeted field surveys to help refine our knowledge of a species' current geographic range. The brush-tailed rock-wallaby (Petrogale penicillata) is listed as endangered in NSW, with the central Evolutionary Significant Unit (cESU) of this species being of particular conservation concern. This species inhabits rocky refugia in rugged and often remote terrain, making it particularly difficult to survey. As a result, there is limited understanding of its current distribution.
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Publication Open AccessThesis DoctoralImplications of grazing management systems incorporating planned rest for biodiversity conservation and landscape function in rangelands(2018-04-14); ; ; ; ; ; Livestock grazing is recognised as a major driver of biodiversity decline and land degradation in rangelands around the globe. Protected areas alone cannot conserve global biodiversity, and therefore off-reserve conservation is necessary to achieve biodiversity conservation outside reserves and improve connectivity between reserves. Grazing management strategies that promote both ecological and production outcomes have the potential to conserve biodiversity and maintain or improve landscape function in agricultural landscapes. However, there is a lack of understanding of the response of biodiversity and landscape function to different grazing management systems in arid and semi-arid rangelands. This thesis explored the effects of commercial grazing practices that incorporate frequent periods of rest from grazing on biodiversity and landscape function, and determined the potential for using these alternative grazing practices to achieve broad-scale conservation outcomes.
A systematic review and meta-analyses of scientific literature comparing grazing management incorporating periods of planned rest (strategic-rest grazing, SRG) with continuously grazed (CG) and ungrazed (UG) systems was undertaken to determine the effect of SRG on ecological and animal production variables. Where significant differences occurred, the trend analysis of ecological and animal production responses to grazing management predominantly favoured SRG over CG, except for animal weight gain, and favoured SRG over UG systems for plant, mammal and bird richness and diversity, but not invertebrate richness and diversity, biomass and ground cover. Most studies that compared plant species composition reported differences in response to grazing management. While we did not find any differences overall between grazing contrasts, meta-analyses of plant richness, diversity, animal weight gain and animal production per unit area indicated that management incorporating longer periods of rest compared to periods of grazing have the potential to improve animal weight gain and production per unit area, but reduce plant richness. The type of SRG system was also important, with multi-paddock SRG systems having lower plant richness relative to CG systems, and SRG systems based on seasonal or deferred grazing having greater diversity than CG systems. Most of the literature comparing SRG with CG or UG did not consider the response of ecological and animal production response variables simultaneously. Greater collaboration between ecological and animal production scientists is recommended to better understand the ecological and socio-economic trade-offs associated with different grazing management strategies.
Understorey floristic species composition and plant biodiversity measures were compared between commercial properties managed under alternative grazing management (incorporating frequent and long periods of rest), traditional (continuous) grazing management, and adjacent ungrazed areas managed for conservation across a broad region of the semi-arid rangelands in western NSW. Significant variation in understorey floristic composition was driven by soil type (clay and sand), season, preceding rainfall and geographic location. These variables were the major drivers of floristic composition. The effect of grazing treatment on floristic composition at the regional scale was comparatively small and not significant. However, infrequent species were more likely to be recorded in conservation areas. Measures of floristic biodiversity varied with the scale of observation, season of sampling and soil type. In comparison to traditional grazing management, alternative grazing management generally resulted in greater understorey floristic species richness and diversity, depending on the season and scale of sampling. Few differences were found in plant species richness, diversity or functional diversity between alternatively grazed properties and adjacent areas ungrazed by commercial livestock and managed for biodiversity conservation. This suggests that alternative grazing management may be compatible with biodiversity conservation on commercial livestock properties in western NSW rangelands, but potentially at the expense of rare species.
Ground cover, soil properties and landscape function were also compared between alternative grazing management, traditional grazing management and conservation management in semi-arid NSW. Alternative grazing management had greater total ground cover in comparison to traditional grazing management systems. However, both alternative and traditional grazing management treatments had significantly less ground cover than adjacent areas managed for conservation. Alternative grazing management properties did not differ significantly to areas managed for conservation in terms of landscape function, but many indices of landscape function (stability, nutrient cycling, landscape organisation index, patch area and average interpatch length) were significantly reduced under traditional grazing management compared to conservation. This suggests that alternative grazing management was more beneficial for landscape function than traditional grazing management.
Significant differences were observed in floristic biodiversity measures, ground cover, soil properties and landscape function between clay and sandy soils in the study region. Clay soils had greater soil organic carbon and organic nitrogen, and lower bulk density than sandy sites. Soil stability, nutrient cycling and landscape organisation indices were also greater on clay than sand soils, and average interpatch length was shorter on clay soils. There was no difference in total ground cover between sand and clay soils, although clay soils had greater vegetative cover than sand soils, while sandy soils had greater cryptogam cover. Floristic biodiversity measures (species richness, evenness, diversity, turnover) were significantly greater on sandy than clay soils at larger plot and site scales, but there was no difference in species richness at the finest scale of sampling (1 m² quadrats). Despite the common perception that clay soils are more resilient to disturbance than sand communities, we found no difference between sand and clay soils in floristic biodiversity measures, ground cover, landscape function, soil organic carbon, soil organic nitrogen, or bulk density in response to grazing management. This indicates that alternative grazing management may provide a sustainable option for conservation of biodiversity and landscape function across both sandy and clay soils in western NSW semi-arid rangelands.
Floristic composition, biodiversity measures and ground cover were also compared at a local scale between an ungrazed public nature reserve and an adjacent rotationally grazed commercial property in Acacia aneura woodland in semi-arid NSW. Significant differences in understorey floristic composition were observed between the two grazing treatments, including a greater frequency of palatable species in the nature reserve and more unpalatable species on the rotationally grazed property. There were no significant differences in understorey floristic species richness, diversity, functional diversity measures or ground cover between the nature reserve and rotationally grazed property. However, these measures increased with distance from water on the rotationally grazed property, highlighting the negative effects of increasing grazing intensity. These results suggest that at a whole-paddock scale (beyond the sacrifice zone of high grazing intensity surrounding water points), rotational grazing management, along with careful management of grazing intensity and stocking rates, has the potential to sustain biodiversity and ground cover and may offer an alternative to grazing exclusion to achieve broad-scale conservation objectives in semi-arid rangelands. However, management would still need to address the impacts on floristic composition.
In conclusion, I found improved understorey plant species richness, diversity, ground cover and landscape function under alternative grazing management compared to traditional grazing management, and few differences in these measures between alternatively grazed and ungrazed areas managed for conservation. These results provide support for utilisation of alternative grazing management practices to improve biodiversity conservation and landscape function outside of the public reserve system in semi-arid rangelands. Results also show incorporation of planned periods of rest in grazing management regimes has the potential to achieve dual ecological and animal production outcomes in grazing landscapes throughout the world. Further research is necessary to understand the circumstances in which commercial grazing is compatible with the conservation of biodiversity, landscape function and animal productivity, and to identify best grazing management practices for biodiversity conservation purposes.2333 377 - Some of the metrics are blocked by yourconsent settings
Journal ArticlePublication Incidence, profiles and correlates of the Cortisol Awakening Response in high-functioning young males with ASD(Elsevier Inc, 2019-01); ; ; Background: The Cortisol Awakening Response (CAR) is sometimes dysregulated in young people with Autism Spectrum Disorder (ASD), but previous findings are mostly based upon group mean data and do not report individual responses. In addition, investigation of the correlates of CAR dysregulation has been limited.
Methods: To provide insight into the individual profiles and correlates of the CAR in young males with ASD, 32 high-functioning male participants with ASD aged between 9 yr and 18 yr completed several measures of anxiety and mood, and provided saliva samples at waking and 30 min later for calculation of the CAR.
Results: Although group mean data showed an expected CAR profile, over half of the participants had a dysregulated CAR. There was a significant interaction between cortisol concentrations at waking and 30 min later and CAR presence/absence, suggestive of the presence of hyper- and hypo-cortisolism. Unlike previous data regarding CAR and mood states in young females with ASD, there were no significant associations between anxiety or depression and CAR dysregulation in this sample of boys with ASD.
Conclusions: The use of the CAR in research and clinical settings must be accompanied by an awareness of the likelihood of individual variability.1774 4 - Some of the metrics are blocked by yourconsent settings
Journal ArticlePublication Predictively modelling the distribution of the threatened brush-tailed rock-wallaby (Petrogale penicillata) in Oxley Wild Rivers National Park, north-eastern New South Wales, Australia(CSIRO Publishing, 2022); ; ;Thomas, Piers; ;Bayne, PaulContext. Species Distribution Models (SDM) can be used to investigate and understand relationships between species occurrence and environmental variables, so as to predict potential distribution. These predictions can facilitate conservation actions and management decisions. Oxley Wild Rivers National Park (OWRNP) is regarded as an important stronghold for the threatened brush-tailed rock-wallaby (Petrogale penicillata), on the basis of the presence of the largest known metapopulation of the species. Adequate knowledge of the species' ecology and distribution in OWRNP is a key objective in the national recovery plan for the species occurring in the Park.
Aims. To model distribution using key GIS-derived environmental factors for the brush-tailed rock-wallaby in OWRNP and to ground-truth its presence through field surveys in areas of high habitat suitability.
Methods. We used Maxent to model the distribution of the brush-tailed rock-wallaby within OWRNP on the basis of 282 occurrence records collected from an online database, elicitation of informal records from experts, helicopter surveys and historic records. Environmental variables used in the analysis were aspect, distance to water, elevation, geology type, slope and vegetation type.
Key results. Vegetation type (37.9%) was the highest contributing predictor of suitable habitat, whereas aspect (4.8%) contributed the least. The model produced an area under the curve (AUC) of the receiver operating characteristic (ROC) of 0.780. The model was able to discriminate between suitable and non-suitable habitat for brush-tailed rock-wallabies. Areas identified in our model as being highly suitable yielded eight new occurrence records during subsequent ground-truthing field surveys.
Conclusions. Brush-tailed rock-wallaby distribution in OWRNP is primarily associated with vegetation type, followed by distance to water, elevation, geology, slope and aspect. Field surveys indicated that the model was able to identify areas of high habitat suitability.
Implications. This model represents the first predicted distribution of brush-tailed rock-wallaby in OWRNP. By identifying areas of high habitat suitability, it can be used to survey and monitor the species in OWRNP, and, thus, contribute to its management and conservation within the Park.
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Publication Open AccessJournal ArticleRotational grazing management achieves similar plant diversity outcomes to areas managed for conservation in a semi-arid rangeland(CSIRO Publishing, 2019); ; ; ; ; Despite the increasing extent of protected areas throughout the world, biodiversity decline continues. Grazing management that promotes both biodiversity and production outcomes has the potential to improve broad-scale conservation and complement the protected area network. In this study we explored the potential to integrate commercial livestock grazing and conservation in a semi-arid rangeland in south-eastern Australia. Understorey floristic composition and diversity were compared at different spatial scales across three grazing management treatments: (1) continuous commercial grazing management where paddocks were grazed for the majority of the year (≥8 months per annum); (2) rotational commercial grazing management where livestock are frequently rotated and paddocks rested for >4 months per annum; and (3) protected areas managed for conservation with domestic livestock excluded and grazed only by native and feral herbivores. The season of sampling, rainfall, soil characteristics and the spatial location of sites were the dominant drivers of variability in understorey plant species composition; the effect of grazing treatment on understorey plant species composition was relatively minor. However, areas managed for conservation and under rotational forms of commercial grazing management generally had greater floristic richness and diversity than continuously grazed areas, the results varying with season (spring/autumn) and soil type (clay/sandy-loam), particularly at fine scale (1-m2 quadrats). These findings indicate that rotational grazing management on commercial properties has the potential to improve biodiversity conservation outside the reserve system compared to conventional grazing management.1528 3