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West Perth, Australia

Enright N.J.,Murdoch University | Fontaine J.B.,Murdoch University | Lamont B.B.,Murdoch University | Lamont B.B.,Curtin University Australia | And 3 more authors.
Journal of Ecology | Year: 2014

1. Changing disturbance-climate interactions will drive shifts in plant communities: these effects are not adequately quantified by environmental niche models used to predict future species distributions. We quantified the effects of more frequent fire and lower rainfall -as projected to occur under a warming and drying climate -on population responses of shrub species in biodiverse Mediterranean- climate type shrublands near Eneabba, southwestern Australia. 2. Using experimental fires, we measured the density of all shrub species for four dominant plant functional groups (resprouter/non-sprouter 9 serotinous/soil seed bank) before and after fire in 33 shrubland sites, covering four post-fire rainfall years and fire intervals from 3-24 years. 3. Generalized linear mixed effects models were used to test our a priori hypotheses of rainfall, fire interval and plant functional type effects on post-fire survival and recruitment. 4. At shortened fire intervals, species solely dependent on seedling recruitment for persistence were more vulnerable to local extinction than were species with both seedling recruitment and vegetative regrowth. Nevertheless, seedling recruitment was essential for population maintenance of resprouting species. Serotinous species were less resilient than soil seed storage species regardless of regeneration mode. Critically, in relation to changing climate, a 20% reduction in post-fire winter rainfall (essential for seedling recruitment) is predicted to increase the minimum inter-fire interval required for self-replacement by 50%, placing many species at risk of decline. 5. Synthesis. Our results highlight the potentially deleterious biodiversity impacts of climate and fire regime change, and underscore weaknesses inherent in studies considering single impact factors in isolation. In fire-prone ecosystems characterized by a projected warming and drying climate, and increasing fire hazard, adaptive approaches to fire management may need to include heightened wildfire suppression and lengthened intervals for prescribed fire to best support the in situ persistence of perennial plant species and of plant biodiversity. This conclusion is at odds with the view that more managed fire may be needed to mitigate wildfire risk as climate warms. © 2014 The Authors. Journal of Ecology © 2014 British Ecological Society.

The calculation and comparison of physiological characteristics of thermoregulation has provided insight into patterns of ecology and evolution for over half a century. Thermoregulation has typically been explored using linear techniques; I explore the application of non-linear scaling to more accurately calculate and compare characteristics and thresholds of thermoregulation, including the basal metabolic rate (BMR), peak metabolic rate (PMR) and the lower (Tlc) and upper (Tuc) critical limits to the thermo-neutral zone (TNZ) for Australian rodents. An exponentially-modified logistic function accurately characterised the response of metabolic rate to ambient temperature, while evaporative water loss was accurately characterised by a Michaelis-Menten function. When these functions were used to resolve unique parameters for the nine species studied here, the estimates of BMR and TNZ were consistent with the previously published estimates. The approach resolved differences in rates of metabolism and water loss between subfamilies of Australian rodents that haven't been quantified before. I suggest that non-linear scaling is not only more effective than the established segmented linear techniques, but also is more objective. This approach may allow broader and more flexible comparison of characteristics of thermoregulation, but it needs testing with a broader array of taxa than those used here. © 2016 Elsevier Ltd.

Tomlinson S.,University of Western Australia | Arnall S.G.,University of Western Australia | Munn A.,University of Wollongong | Bradshaw S.D.,University of Western Australia | And 5 more authors.
Trends in Ecology and Evolution | Year: 2014

The ecological processes that are crucial to an animal's growth, survival, and reproductive fitness have energetic costs. The imperative for an animal to meet these costs within the energetic constraints of the environment drives many aspects of animal ecology and evolution, yet has largely been overlooked in traditional ecological paradigms. The field of 'ecological energetics' is bringing comparative physiology out of the laboratory and, for the first time, is becoming broadly accessible to field ecologists addressing real-world questions at many spatial and temporal scales. In an era of unprecedented global environmental challenges, ecological energetics opens up the tantalising prospect of a more predictive, mechanistic understanding of the drivers of threatened species decline, delivering process-based modelling approaches to natural resource management. © 2014 Elsevier Ltd.

Tomlinson S.,University of Western Australia | Phillips R.D.,Kings Park and Botanic Gardens | Phillips R.D.,Australian National University | Phillips R.D.,University of Western Australia
Journal of Zoology | Year: 2012

High ambient temperatures can adversely affect insects through high evaporative water loss (EWL) and reduction of metabolic activity through enzyme denaturation. Establishing the relationship between the temperature at which these processes become detrimental and regulatory behaviour is critical in resolving the mechanisms by which insects cope with physiologically stressful environments. Here, we compare levels of metabolic rate and EWL measured by flow-through respirometry with field activity in the ichneumonid wasp Lissopimpla excelsa. Metabolic rate increased to a maximum of 10.8±0.4mLCO 2.g -1.h -1 at 35°C before decreasing to 8.4±0.4mLCO 2.g -1.h -1 at T a = 40°C. EWL showed an exponential pattern of increase, with a significant increase in EWL from T a = 12°C to T a = 35 and 40°C. Male wasps were active in the field from T a = 20.1 to 36.8°C (peak activity T a = 26.5°C and relative humidity = 44.4%), though activity levels were most strongly correlated with time of day. Being active in the mornings may be advantageous in that temperatures are warm enough to maintain activity but avoid excess energy expenditure and EWL. Furthermore, food or calling females may be most abundant during this period. Based on a consensus allometric scaling relationship derived for insect resting metabolic rates, the metabolic rate of L. excelsa at T a = 25°C was higher than predicted, as was EWL. Since the present study is the first describing the metabolic physiology of an ichneumonid wasp, it remains unclear whether this pattern is characteristic of ichneumonids in general of L. excelsa in particular. © 2012 The Zoological Society of London.

James J.J.,University of the Sierra | Sheley R.L.,U.S. Department of Agriculture | Erickson T.,Kings Park and Botanic Gardens | Erickson T.,University of Western Australia | And 4 more authors.
Journal of Applied Ecology | Year: 2013

Drylands support over 2 billion people and are major providers of critical ecosystem goods and services across the globe. Drylands, however, are one of the most susceptible biomes to degradation. International programmes widely recognize dryland restoration as key to combating global dryland degradation and ensuring future global sustainability. While the need to restore drylands is widely recognized and large amounts of resources are allocated to these activities, rates of restoration success remain overwhelmingly low. Advances in understanding the ecology of dryland systems have not yielded proportional advances in our ability to restore these systems. To accelerate progress in dryland restoration, we argue for moving the field of restoration ecology beyond conceptual frameworks of ecosystem dynamics and towards quantitative, predictive systems models that capture the probabilistic nature of ecosystem response to management. To do this, we first provide an overview of conceptual dryland restoration frameworks. We then describe how quantitative systems framework can advance and improve conceptual restoration frameworks, resulting in a greater ability to forecast restoration outcomes and evaluate economic efficiency and decision-making. Lastly, using a case study from the western United States, we show how a systems approach can be integrated with and used to advance current conceptual frameworks of dryland restoration. Synthesis and applications. Systems models for restoration do not replace conceptual models but complement and extend these modelling approaches by enhancing our ability to solve restoration problems and forecast outcomes under changing conditions. Such forecasting of future outcomes is necessary to monetize restoration benefits and cost and to maximize economic benefit of limited restoration dollars. © 2013 The Authors. Journal of Applied Ecology © 2013 British Ecological Society.

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