Monday 30th Nov 2015
Managing species across vast spatial areas: does one size fit all?
Aaron C. Greenville, Glenda M. Wardle, Vuong Nguyen and Chris R. Dickman
Understanding how the spatial and temporal dynamics of populations vary across the landscape is fundamentally important to managing and conserving species. For example, populations may fluctuate in synchrony, or exhibit other forms of spatial sub-structuring, due to intrinsic population parameters or to influences from environmental factors. Importantly, synchronous populations may be at greater risk of extinction if all populations are decreasing to zero at the same time, thereby reducing rescue through colonisation. Different species may not have similar dynamics, even if they share the same environment and thus unravelling the spatial dynamics of multiple species provides vital information about what scale to apply management actions.
Using long-term data (17‑22 years) across a large-scale study region (8000 km2) in arid central Australia, we test for regional synchrony in a population driver, annual rainfall, across nine sites (>20 km apart). We then draw from examples from small mammal and reptile populations and investigate if each species exhibits synchrony. For species that did not exhibit synchrony, we used multivariate autoregressive state-space (MARSS) models to explore four other sub-population structures. We also use the MARSS models to identify important drivers that may regulate populations of these species.
We show that species exhibited different spatial population structuring and respond to extrinsic factors in different ways. We conclude that investigating how the spatial connections among populations interact with their temporal dynamics and eventual persistence or decline, is important for determining the appropriate scale to implement management actions and that “one size does not fit all”.
Ecosystem risk assessment of Georgina gidgee woodlands in central Australia
Glenda M. Wardle, Aaron C. Greenville, Anke S. K. Frank, Max Tischler, Nathan J. Emery and Chris R. Dickman
Ecosystem risk assessments are a new instrument in the ecological manager’s toolbox. The key component is a set of quantitative decision rules that address the distribution and function of the target ecosystem. Here we focus attention on a relatively poorly known ecosystem. Georgina gidgee woodlands are widespread across central Australia but occur in relatively small patches of a few hectares.
To address the extensive knowledge gaps for this understudied ecosystem, we gathered data to provide the first description of the characteristic biota, distribution of dominant species and the processes that support the ecosystem. Criteria evaluated included historical, current and future declines in spatial distribution, the extent and area of occupancy, and disruptions to abiotic and biotic processes, including uncertainty in the bioclimatic models.
The risk status of Georgina gidgee woodlands was vulnerable based on the degradation of abiotic and biotic processes. Bioclimatically suitable habitat was predicted to decline by at least 30% in eight scenarios over the period 2000 to 2050. Pressures from grazing, weed encroachment and altered fire regimes further threaten the ecosystem; therefore, vulnerable status was also recorded for future declines based on altered biotic processes. Accurate mapping and monitoring of the study ecosystem should receive priority to inform conservation decisions, and sustainable grazing practices encouraged.
Our findings highlight the importance of other patchily distributed ecosystems that may also have escaped attention despite their contribution to supporting unique biodiversity and ecosystem services. It is timely that environmental monitoring and policy account for these natural assets.
Tuesday 1st Dec 2015
1120-1125: Stefan Caddy-Retalic, Ballroom C
An Isotopic TREND: Water stress in South Australian flora
Caddy-Retalic, S., Wardle, G.M., Lowe, A.J. & McInerney, F.A.
Water availability is a major influence on plant physiology and where plants can live in the environment. Plant distributions are therefore expected to shift under changed climates but a major barrier to predicting such shifts is our limited understanding of how plants respond to stress caused by increased aridity. A plant that is water-stressed will be forced to limit stomatal opening to reduce water loss by evapotranspiration. As this changes the levels of carbon isotopes in the leaves it provides a way to measure contemporary adaptation by plants to changing conditions. Measurement of stable carbon isotope ratios in leaves is an established methodology for detecting water stress but is seldom applied at a landscape scale. To investigate how plants respond to water stress, stable carbon isotope ratios were measured in the 161 species found at ≥4 of the 42 TREND sites established by TERN. These sites cover a strong bioclimatic gradient of >700km from the South Australian coast to the arid interior. Species tested reflect the diversity of the Australian flora, including trees, shrubs, forbs, yakkas, grasses, sedges, vines, chenopods, mistletoes and ferns; as well as native and introduced species.
Most of the 149 (including 33 previously unknown) C3 species showed correlations between water availability and carbon isotope ratios were found within most C3 plants and as a whole across the 700km gradient. The 12 (including 1 previously unknown) C4 species predominated in the drier regions and did not show a clear correlation between aridity and carbon isotope ratios.
1445-1500: Vuong Nguyen, Ballroom A
Life form explains consistent temporal trends across species: the application of dynamic factor analysis
Vuong Nguyen and Glenda M. Wardle
Long-term survey data are best for detecting trends and guiding management decisions, however in practice, such data are scarce. Thus to improve ecological inferences an attractive option is to borrow information about population parameters from multiple data sources, including other species. If species respond similarly across space or time then it is possible to understand trajectories at the aggregate level and manage accordingly.
Dynamic factor analysis (DFA) is ideal for comparing multiple time series data sets as it retains the temporal order of the observations. Importantly, by identifying if any trends over time are shared among species, the temporal dynamics of a large number of species can be simplified to fewer trends. An added advantage is that these common trends reveal the potential to share information across species that are less well sampled.
Here we apply DFA models to time series data (9 years) of abundance for multiple plant species (27-30) across multiple sites (4) in arid central Australia and search for patterns related to life form. Five common trends were identified and they were strongly associated with life form. Forbs and grasses showed high levels of synchrony in response to rain events, but this was less pronounced for shrubs and subshrubs. Interestingly, these life form responses differed across sites, at large (>20km) spatial scales.
We can recommend to managers that plant life form reasonably predicts temporal responses, but only for local spatial scales – offering some justification for borrowing strength to supplement data for poorly sampled species.
Hot, hotter, too hot: thermoregulatory behaviour and microhabitat use of military dragons (Ctenophorus isolepis)
Eveline Rijksen, Christopher Dickman and Mathew Crowther
Most studies predicting large-scale patterns in the thermal tolerance of ectotherms use air temperature, often mean annual or seasonal, measured at a height of 1-2m, to index thermal environment. These temperatures are readily available but poorly reflect the environmental conditions experienced by individual ectotherms, especially in variable climates. We measured temperature of individual components in the micro-habitat of the spinifex covered sand-dunes of the Simpson Desert. Especially temperatures in exposed habitats far exceeded the physiological thermal limits of most ectotherms. They must therefore rely on behaviour to avoid overheating during the warmest times of the day. Using temperature sensitive VHF transmitters, we recorded animal temperature and constructed a fine-scale overview of micro-habitat use of military dragons (Ctenophorus isolepis), on both a temporal and spatial scale. We show that military dragons do not have sufficient physiological tolerance to survive in open habitat and rely on behavioural shifts to exploit local habitat heterogeneity to reduce their body temperature. Shaded areas and burrows are essential in providing refugia from extreme heat. Using maximum or mean air temperature simplifies the reality of the thermal conditions experienced by terrestrial ectotherms and underestimates the importance of behavioural thermoregulation, including the importance of refugia for survival.
1745-1930: Caroline Cheung, Barbara Rice Memorial Poster Session, Gallery Level 1
Cultivating botanical literacy with campus flora: a mobile engagement tool
Caroline Cheung, Glenda Wardle, Rosanne Quinnell
Urbanised environments reduce the opportunities to connect with nature. In turn, this limited experience of the variety of species, and particularly plants, undermines the educational objective of building an ecologically- and botanically-literate society. What is needed to improve botanical literacy is to overcome the reluctance many people have to learning about plants by making the information accessible and engaging.
With this in mind the Campus Flora project was developed as a partnership between staff and undergraduates at the University of Sydney. It is an App designed to address the issue of ‘plant blindness’ (lack of awareness of plants) by introducing people to plants that they encounter in their daily life. Campus Flora provides educational information, relevant for a novice or expert, and offers botanical narratives via ‘trails’ using the botanical resources within the campus landscape.
CampusFlora builds on this botanical framework to offer broader learning experiences. Firstly, it leverages off the innovative ‘anywhere and anytime’ mobile technology, to pique the interest of technology-savvy students. Secondly, the project also engages with ecology students, or any life-long learners. For example, CampusFlora is used as a complementary tool to improve the plant identification skills needed to record phenological observations for a citizen science program called ClimateWatch. The Campus Flora app offers exciting future prospects; from its inception it has been developed to be an open system, shareable across institutions and platforms. A network of Campus Floras is being planned that through partnerships, will enable students to collaborate on large-scale studies in urban ecology.
Wednesday 2nd Dec 2015
1415-1515 and 1600-1730: SYMPOSIUM: Modern ecology – challenges and opportunities
Ecologists traditionally share data among their trusted networks to create new science. In modern ecology though researchers often complement their own data with others data obtained from public repositories, thanks to colleagues increasingly publishing their data online (e.g. DRYAD, ӔKOS). When publishing data, we reasonably assume the practice is the same as article publishing. Some similarities exist but the differences are colossal and new to science practice in ecology (e.g., data integrity, copyright, licensing, data derivatives, citations). Ecologists are in unchartered waters when it comes to data publishing (DP) as guidelines for data authors are non-existent and still developing. This symposium is a first for ESA conferences and very timely. It engages all participants by first introducing the challenges, opportunities and ‘best practice’ DP, followed by speed presentations DP case studies, open discussion of potential principles to adopt as a basis for establishing a DP ethos in ecology and concludes with a synthesis of ideas and opportunities for publishing a set of DP guidelines.
Thursday 3rd Dec 2015
1100- 1115, Thomas Newsome (@NewsomeTM)
What did the wolf eat? Understanding the diet of a globally distributed predator
Grey wolves (Canis lupus) are one of the most extensively studied large carnivores, but there has been no detailed review of the species’ feeding ecology across the globe. This is despite growing debate about how to conserve or restore wolf populations while limiting their impacts on wild or domestic ungulates. Thus, in order to facilitate an informed discussion of grey wolf conservation and management, it is critical to develop a clear understanding of grey wolf dietary ecology across landscapes with varying levels of human influence. In this presentation I will summarise the results of a review that compiled grey wolf dietary data from 167 studies incorporating 89,674 scat and stomach samples. I will outline the extent to which grey wolf diet varies among and within North America, Europe and Asia. Finally, I will highlight the extent to which grey wolves have adapted to human-altered ecosystems and discuss the broader implications of the results for the conservation and management of other canid species throughout the globe.
1200-1205, Stephanie Yip
Diet of feral cats during boom and bust cycles of their principal prey
The impact of feral cats (Felis catus) on native wildlife is considered to be one of the most significant conservation issues in Australia, with ‘Predation by feral cats’ listed as a Key Threatening Process under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999. To increase understanding of how cats forage when their principal prey vary, we analysed the diets of feral cats that were culled during periods of scarcity and abundance of the native long-haired rat, Rattus villosissimus. Feral cats were shot during culling operations in semi-arid grassland habitats in central Queensland, Australia and the stomach contents later identified. The results were used to test some predictions of foraging theory: animals should forage so as to maximize their net rate of energy gain or to minimize their risk of starvation and, in situations where prey numbers fluctuate dramatically, will eat ‘optimal’ prey when it is abundant, but expand their diet to include other prey types when it is scarce. The results largely accorded with expectations, with cats focusing primarily on rats when they were at the peak of their boom cycle, and expanding their diet to encompass a much broader range of prey when rat numbers crashed during their bust phase. While feral cats are often thought to be specialist predators, they may be better considered as facultative specialists that will shift their diet in predictable ways in response to changes in the abundance of primary prey.