Welcome to the homepage of the Desert Ecology Research Group (DERG) based out of the University of Sydney.
DERG members have participated in organising a symposium and workshops at #ESA16! Details are:
Surviving the dry: how diversity is maintained in the arid zone
30th November and 1st December 2016
This symposium in convened by the Arid Ecology Research Chapter of ESA, and is a follow-up from the research chapter’s first symposium held at ESA 2011 in Hobart: The greening of arid Australia – opportunities and lessons from extreme years (see Austral Ecology Volume 38 (7), November 2013). Over the past few years serious rainfall deficiencies have gripped many parts of Australia and long-term drying trends cannot be explained by natural variability alone. Arid and semi-arid organisms have successfully developed many survival strategies to live in a water-limited environment, and Australia’s dry interior has become a diverse and complex system. This symposium aims to bring together researchers from a range of backgrounds to explore how species diversity is maintained in a system where droughts are the norm, and provide lessons for a continent that is faced with longer and more severe droughts due to a changing climate. The presentations will cover a range of arid zone based research that consists of both specific, previously unpublished research and broader syntheses.
Professor Glenda Wardle
Dry, drier, driest: extreme years and potential ecosystem collapse
30th November 4:30 PM – 4:45 PM
Environments are changing. More frequent extreme conditions such as prolonged droughts, floods, heatwaves and fires are expected, but how much change is possible before ecosystem collapse, remains unknown. Forecasts of climate futures will help, but we need to be aware of regional differences and capture the uncertainties in our planning. We do know that these intense events will add stress to the rangeland systems that support human food production and biodiversity. Drylands, in particular, are water-limited and operate differently in dry, or wet years, when episodic pulses of resources drive increases in productivity. Increased extremes have the potential to disrupt the function of these highly dynamic and complex systems through feedbacks, synergies and through memory or delayed responses to change.
Using our long-term work in the Simpson Desert as a case study, we explore the trends in productivity and the connectedness and heterogeneities that support the persistence of the ecosystem through dry times. Theory tells us that ecosystems may shift states abruptly when they cross critical thresholds. For example, arid grasslands may no longer have the capacity to return to a productive state following good rains. This happens under desertification, where the same plant growth cannot be supported — with flow on consequences for the entire ecosystem. We will illustrate the knowledge gaps in quantifying ecosystem collapse using our IUCN ecosystem risk assessment of the Georgina gidgee woodlands. We conclude by arguing that without long-term data on trends we cannot hope to anticipate ecosystem collapse and take appropriate action.
Spatial and temporal variability of a threatened arid-zone rodent in drought refuges
30th November 5:15 PM – 5:30 PM
The characteristically high annual rainfall variability across the Australian arid zone leads to large fluctuations in the abundance and distribution of small mammals. Long dry periods related to low abundance of small mammals are interrupted by brief large magnitude rainfall events, which drive high abundance of small mammals. There are two ways in which species are thought to persist throughout the long dry periods; at low levels throughout the landscape or in discrete patches of habitat with a more consistent supply of resources – drought refuges.
Drought refuges may vary spatially and temporally within and between long dry periods depending on the characteristics of the resources relied upon by a species. The plains mouse (Pseudomys australis), a threatened arid zone rodent, is presented as a case study of a drought refuge small mammal. The plains mouse undergoes smaller magnitude fluctuations in abundance and area of occupancy within cracking clay refuge habitat during the long dry periods, and irrupts out of this refuge habitat into the surrounding landscape in response to large magnitude rainfall events. Understanding the spatial and temporal variability of the plains mouse in refuge habitat allows for the development of targeted management of the species when it is at the most vulnerable stage of its population cycle. This is particularly important in arid Australia where mammal extinction has been concentrated.
Dr Aaron Greenville
Surviving the dry: one species’ bust is another species’ boom
1st December 11:00 AM – 11:15 AM
Images of drought-stricken land invoke a sense of disaster in our euro-centric view of Australia, but for a continent where 70% of its area is semi-arid or arid, dry times are the norm. Yet in the arid zone, Australia harbours some of the most rich and diverse assemblages of species in the world. Through our long-term monitoring in the Simpson Desert, we know that small vertebrates continue to occur in low population densities during the dry periods. Some species may take advantage of drought refuges, while others benefit from changing abiotic and biotic conditions that occur during dry conditions. For example, in contrast to more mesic environments, the risk of wildfire is low during droughts due to the lack of connectivity in ground fuels. Secondly, top-down suppression of introduced meso-predators is stronger in bust times compared to boom. Here we argue that the diversity of small vertebrates in central Australia is maintained in the dry times, albeit at low densities for many of the constituent species populations, through a counterintuitive set of biotic and abiotic processes compared to those that occur in the boom times. However, these processes are under threat from the degradation of drought refuges, barriers to dispersal and dingo control programs, which increase the difficulty in predicting responses of arid zone species to increases in the severity and length of droughts that are predicted to occur under future climate change.
Nature and ecology photography workshop (at Kings Park)
Friday, December 2, 2016
8:00 AM – 3:00 PM
COST: $35 Co-ordinators: Alan Kwok and Aaron Greenville. email: email@example.com Location: Kings Park and Botanic Garden Photography has become an integral part of many aspects of ecology, from its use in documenting observations, through to its use as a technique for valid data collection. Additionally, photography can be complementary to the science of ecology, forming a potentially high-impact and visual form by which to convey ecological phenomena to a broader audience. The aim of this workshop is to give ecologists an understanding of the fundamental principles of photography that will help them take the photographs they visualise. We will also cover some more advanced photography techniques that will hopefully inspire participants to be more creative with their photography. The workshop will also be fluid, catering to the skill levels and interests of the participants, and will include theoretical and practical components. Both theoretical and practical components will be held at Kings Park and Botanic Garden. A substantial portion of the course will be outside in the Park, where theoretical principles can be demonstrated and participants can engage in active learning. Please note: Participants are requested to bring a camera, though it is not compulsory. Ideally, a camera with control over aperture and shutter speed is preferred, but not essential. Topics covered include: Fundamental technical principles of photography – demystifying shutter speeds, aperture, and all the rest Painting with light – type, direction, and colours Composition – it’s all in your mind Photography as a complement to science – photos as a use for telling a story, explaining a phenomenon, or for documentation, all of which are useful for public outreach and engagement. Specific uses of photography in ecology – photo points, photo-stacking (increasing detail), surveys Post-capture – “data” processing to enhance photos, photo management, etc. The workshop will be run by ESA members, Drs Alan Kwok and Aaron Greenville who are also photographers, whose skillsets cover a range of subjects including macrophotography, astrophotography, landscape, and general nature and wildlife photography. Inclusions: Transport from Rydges Esplanade Hotel to Kings Park (and return if required) We would like to thank Botanic Gardens and Parks Authority for their generous support of this Field Trip
Working with Terrestrial Ecosystem Research Network
Friday, December 2, 2016
1:30 PM – 4:30 PM
A photo of DERG, as contributors to the distributed Nutrient Network (NutNet) is featured in yesterday’s The Conversation article “Gone is the solitary genius – science today is a group effort”.
This big trip in April 2013 was the ‘birth’ of our two NutNet sites and exclosures.