I have been fortunate enough to join the D.E.E.P lab in between finishing my honours at the end of 2015, and starting my PhD in 2017. I’ve been most excited to engage my interest in quantitative ecology, and gain new experiences with various statistical approaches! I am currently working on two separate projects within the D.E.E.P lab: one investigating the effects of the recent Tasmanian bushfires on temperate wet sclerophyll forests, and the other modelling population demographics of the echidna, and evaluating the influence of climate on this species. These projects have involved a mix of spatial point pattern and mark-recapture analyses, general modelling, as well a large amount of field research. Read more about these projects below!
Research within D.E.E.P:
Importance of long term monitoring for evaluating forest disturbance: a case study from the 2016 Tasmanian wildfires
Disturbances are important natural drivers of forest ecosystem dynamics, and strongly influence the structure and functioning of forest ecosystems. Forest disturbance regimes are intensifying in many parts of the world, with climate change expected to drive further changes in the size, severity and frequency of disturbance events globally. These future changes in disturbance regimes are likely to alter forest ecosystems across the globe, with potentially far reaching impacts on their biological diversity.
A recent and close-to-home example of forest disturbance driven by climate change can be seen in the Jan/Feb 2016 Tasmanian wildfires, which reportedly burnt 97,000 hectares of forest across the state. These burns included larges areas of relict alpine species which had previously existed in the landscape without fire for an estimated 150 million years. These fires were attributed to a record-breaking dry spring, followed by a continued dry and warm summer, which left long unburnt areas uncharacteristically dry and vulnerable to ignition by lightning. With the occurrence of such fire events predicted to increase into the future, it is important to know how ecosystems respond to fire in order to discern ecosystem resilience. This can be difficult to quantify, however. Additionally, in the case of Tasmania, much of the fire related research on a dominant forest type, temperate wet sclerophyll forest, is done in Victoria. Tasmanian wet sclerophyll forests, though the same forest type in name, may be functionally different in floristics and nature of response to fire.
With this research we aim to examine the influence of fire on the structure and function of Tasmanian wet sclerophyll forests, and evaluate the implications for biodiversity and the sustainable management of Tasmanian temperate forests. This investigation has taken advantage of an opportunity provided by the recent Tasmanian fires, which intersected with a pre-existing long-term forest monitoring plot (AusPlots). Natural experiments like this are rare but highly valuable in the quest to quantify biotic responses to fire.
Uniting pre and post fire floristic data, we have quantified the mortality and regeneration of eucalypt, acacia and other tree species, and the dominant tree fern D. antarctica, in response to wildfire. We have also evaluated the density and pattern of seedling establishment in eucalypts and acacias between burnt and unburnt forests. In addition to this, we have also evaluated faunal response to fire, taking advantage of my own passion for birds, as well as an enthusiasm for invertebrates held by undergraduate D.E.E.P researcher Mel Gerwin. Coupling this data with modelling and spatial point pattern analysis, we have been able to make inferences about changes in forest composition and structure brought about by the fire, and speculate potential implications for biodiversity in the face of changing fire regimes.
This study will be important, not only to provide region specific information on the response of Tasmanian wet sclerophyll forests to fire, but also as a broader demonstration of the value of long term forest monitoring plots. Opportunities derived from long term forest monitoring will be critical for determining ecosystem resilience in the face of intensifying disturbance regimes, which are expected to be among the most severe climate change impacts on forest ecosystems in the future.
Population modelling of the Tasmanian Echidna (Tachyglossus aculeatus)
Collaborators: Stewart Nicol
Estimations of demographic parameters, such as population recruitment and survival, are central to research questions in wildlife management, and continue to be of fundamental interest to ecological research. Estimates of these parameters often guide management and conservation decisions for wildlife populations, where baseline demographic information can be particularly useful for evaluating potential population level impacts of threats. Indeed, concern about the ecological impacts of global climate change has raised interest in how demographic parameters, such as survival and fecundity, may be inﬂuenced by climatic conditions.
The short-beaked echidna (Tachyglossus aculeatus) is a myrmecophagous monotreme with a near ubiquitous distribution across Australia. Echidnas are sensitive to climate, with daily and annual patterns of activity and reproduction highly dependent on ambient temperature. Climatic changes relating to temperature and rainfall have the potential to impact echidna populations through influencing timing of hibernation, reproduction and development, frequency and duration of torpor (and thus rate of energy expenditure), and may ultimately effect survival and reproduction of this species into the future. While certain aspects of the temporal and spatial ecology of this species have been well studied, general life history trends of echidnas remain enigmatic, and the cryptic nature of this species has confounded efforts to obtain reliable population estimates.
We are conducting a series of analyses on a long-term, 19-year dataset to better characterise population demographics of the echidna, and empirically test hypotheses about the inﬂuence of climatic conditions on annual survival and reproduction. This has included mark-recapture analysis, to characterise demographic parameters and evaluate climatic influences, and spatial point pattern analysis, to evaluate distribution patterns of echidnas in the landscape, and the influence of resources on echidna occupancy. We plan to use this information to build population models for this species, in order to evaluate the drivers of echidna occupancy, and predict where echidnas should be now, and how their distribution may change into the future. Results from this study will provide information on the impacts of climate change on this unique species, and will provide vital knowledge needed to ensure successful population management of this species into the future.
Research outside of the D.E.E.P lab
My main research interests are in quantitative ecology, anthropogenic disturbance, and wildlife disease, though my previous field and research experience has encompassed a broad range of areas. Before joining the DEEP lab I completed my honours degree on platypus, where I was interested in the use of non-routine statistical approaches as a means of enhancing research in complex freshwater systems. I used structural equation modelling to assess platypus stream use, and the influence of forest harvesting on platypus occurrence and long term population abundance and health.
After completing honours I worked as an ecology research intern for the Australian Wildlife Conservancy, where I assisted in endangered species programs at sanctuaries in the heart of arid Australia. Here I was fortunate enough to trap and handle a myriad of Australian mammals rarely seen by people, including numbats, bilbies, bridled nailtail wallabies, boodies, woylies and mala. I also discovered a passion for birds while living on joint BirdLife and AWC managed properties, as well as a keen interest in reptiles during pitfall biodiversity surveys in Central Australia. During this time I also gained experience in a variety of other research areas, including research on feral animal ecology, mesopredator release of sand goannas, habitat use of numbats, burrow activity monitoring of great desert skinks, and vegetation monitoring.
I will soon be leaving the D.E.E.P lab to start my PhD with the Griffith Wildlife Disease Ecology Group. I plan to investigate the host-pathogen dynamics of Hendra virus in Australian flying foxes though a combination of modelling, field and laboratory research. Wish me luck!
Lunn, T., M. Gerwin, J. Buettel, B. Brook (2017). Importance of long term monitoring for evaluating forest disturbance: a case study from the 2016 Tasmanian wildfires. PLOS ONE (in prep)
Lunn, T., J. Buettel, S. Nicol, B. Brook (2017). Population modelling of the Tasmanian Echidna (Tachyglossus aculeatus). Austral Ecology (in prep)
Lunn, T., S. Munks, S. Carver (2017). Impacts of timber harvest on stream biota – an expanding field of heterogeneity. Biological Conservation (in prep)
Lunn, T., S. Munks, S. Carver (2017). Causal processes of a complex system: modelling stream use and disturbance influence on the platypus (Ornithorhynchus anatinus) (in prep)
Lunn, T., J. Macgregor, S. Munks, S. Carver (2016). Dermatophilus congolensis infection in platypus (Ornithorhynchus anatinus), Tasmania, Australia, 2015. Journal of Wildlife Diseases, 52(4).
Carver, S., S. N. Bevins, M. R. Lappin, E. E. Boydston, L. M. Lyren, M. Alldredge, K. A. Logan, L. L. Sweanor, S. P. D. Riley, L. E. K. Serieys, R. N. Fisher, T. W. Vickers, W. Boyce, R. McBride, M. C. Cunningham, M. Jennings, J. Lewis, T. Lunn, K. R. Crooks, and S. VandeWoude (2016). Pathogen exposure varies widely among sympatric populations of wild and domestic felids across the United States. Ecological Applications, 26(2):367-381.