New alpine additions to La Trobe University Herbarium

Through January 2018, RCAAE summer student Bianca Berto surveyed the distribution of 10 rare and threatened plants across the Bogong High Plains. These included some of the rarest plants in Victoria including Abrotanella nivigena (Snow-wort) and Plantago glacialis (Star-leaf Plantain).

Bianca has recently submitted 58 voucher specimens from this study to the La Trobe University Herbarium. These specimens include all 10 survey species (Abrotanella nivigena, Argyrotegium nitidulum, Deyeuxia affinis, Diplaspis nivis, Juncus antarcticus, Oreomyrrhis pulvinifica, Pappochroma paludicola, Paranetennaria uniceps, Plantago glacialis, Utricularia monanthos) from 21 locations. This submission is a valuable and significant contribution to the LTU Herbarium and increases our knowledge of where these threatened species currently occur in the landscape.

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Pictured: Voucher specimens of Juncus antarcticus (Left) and Abrotanella nivigena (Right) submitted by Bianca.

More details about this survey can be found in the accompanying report.

Burramys genetic rescue program a finalist for Museum Australia Eureka Prize

Museum Australia has announced the finalists for their 2018 Eureka Prizes, with RCAAE Deputy Director Ian Mansergh and member Dean Heinze part of the Burramys Genetic Rescue Team, who are one of three finalists for the NSW Office of Environment and Heritage Eureka Prize for Environmental Research.

The team, a collaboration between La Trobe University, Melbourne University, UNSW and Mt Buller Resort, prevented the local extinction of an isolated Burramys population through the introduction of male Burramys from another population, thereby increasing genetic diversity and fitness.

See the short video below explaining their research.

The scientific publication of this research can be found in Nature Communications.

First Class Honours for RCAAE students Aviya Naccarella and Lauren Szmalko

Congratulations to RCAAE student members Aviya Naccarella and Lauren Szmalko on receiving first class Honours. Lauren’s project assessed the seed dispersal potential of many alpine species on the Bogong High Plains, under the supervision of Dr John Morgan. Aviya’s project exploring changes in alpine and subalpine treelines within the Victorian Alps under the supervision of Dr Susanna Venn and Dr John Morgan. Their theses are summarised below:

Lauren Szmalko – A quantitative assessment of seed dispersal capability of alpine species

Seed dispersal is a vital part of a plant’s life cycle as it enables progeny to reach new sites that are suitable for burial, subsequent germination and survival into the next generation. Plant species vary dramatically in their ability to disperse, and this will have consequent implications for species to track changes in bioclimatic envelopes as a result of rapid changes in climate. Such responses are particularly acute for alpine species that are already near/at the cold edge range. In this study, understanding alpine plant species dispersal was addressed by first using building on published models to predict dispersal distance in Australian alpine plants, using a combination ‘soft’ and ‘hard’ plant traits (e.g. terminal velocity). Estimates of seed dispersal in the field were conducted using a novel seed trap to trap seed over one seed dispersal season. Seed dispersal models were improved by the inclusion of terminal velocity because because its inclusion in models affordedgreater discrimination in predicting species dispersal distance of many Asteraceae Seed trapping in the field detected 34% of species in the standing flora in traps, suggesting a capacity for either short or longer distance dispersal. One case of long-distance dispersal was found; the exotic daisy, Cirsium vulgare, is thought to have travelled up to 2 km before being captured. This study highlights that alpine seed dispersal is likely to be of the order of only a few metres for many species. Hence, their capacity to track climate change via dispersal is limited. However, if seed dispersal is not advantageous on top of alpine summits, then a better understanding of the implications for non-dispersal and vegetation change need to be quantified.

 

Aviya Naccarella – Comparative change in the spatial and temporal dynamics of alpine and subalpine treelines across the Victorian Alps, Australia

Treelines are one of the most conspicuous vegetation transition zones driven by the sensitivity of trees to low temperatures. Consequently, treelines are predicted to advance beyond their current position in response to rising global temperatures. Despite the prominence of treeline studies globally, Australian treeline studies remain underrepresented. A recent increase in bushfire occurrence (2003, 2007 and 2013) across the Victorian Alps has provided the opportunity to study the combined effects of rising temperature and fire frequency on alpine and subalpine treelines formed by Snow Gum (Eucalyptus pauciflora). This study used repeat photography dating back ~100 years, re-visitation surveys over the last ~20 years and dispersal modelling to assess temporal and spatial change. Treeline dynamics and woodland structure have remained relatively stable at landscape and local scales. There is continued recruitment of seedlings above treeline. However, high turnover of individuals suggests there are limiting factors impacting survival, such as competition, drought, frost. Bushfires had marginal effects on dynamics, with high survival. Two fires within ten years may have impacted recruitment processes in conjunction with site-specific influences. Overall, this study suggests the stability of Victorian alpine and subalpine treelines is likely due to a combination of limiting factors which continue to inhibit establishment and persistence of E. pauciflora above treeline. These findings resonate with global studies suggesting the influence of site-specific limiting factors are driving the variable response of global treelines to rising temperatures.

Congrats to Emma Sumner on her first class Honours!

Emma Sumner has recently completed her honours under John Morgan with the RCAAE at La Trobe University. Emma studied the biotic and abotic factors that affect local distributions of a model alpine plant, Alpine Podolepis (Podolepis robusta). This was investigated using various field and laboratory experiments designed to understand what controls the local distribution of this plant.

Emma found that Alpine Podolepis has a far greater fundamental niche than is currently realised at Mt Hotham, with facilitative interactions playing a strong role across range edges. A transplant experiment along a temperature and moisture gradient found that close interspecific neighbours significantly increased survival and growth of planted seedlings, compared with seedlings planted in canopy gaps. This pattern was found to be consistent, even below the current distribution of Alpine Podolepis where it was expected that close interspecific neighbours would result in stronger competitive interactions.

Emma’s thesis highlight the importance of facilitative interactions at the seedling stage in the alpine zone, demonstrating that biotic factors act to constrain or widen the theoretical niche. Emma argues that biotic interactions, dispersal limitation, and recruitment processes may enforce stronger limits to geographic distribution than climatic tolerances per se and that predictions on how plant species may respond to climate change would benefit from incorporating these factors.

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New Honours Students

Two new Honours students have recently joined the RCAAE under the supervision of Dr John Morgan and Dr Susanna Venn.

Lauren Smalko

Lauren is investigating the potential for alpine herbs and grasses to disperse. Currently there is almost no field data on seed dispersal, but it is an important research topic given the need for species to disperse to track their changing climate envelope.  Using a series of novel seed traps (that capture seeds dispersing at 30 cm and 1.8 m above the ground), she will quantify seed rain and the seed traits that help predict dispersal.

Aviya Naccarella

Aviya is investigating long-term change in alpine and sub-alpine treelines in the Bogong High Plains area. Treelines are susceptible to movement as climate warming occurs, but there have been no recent assessments of this phenomenon in Australia. Using permanent transects established in 1999-2002, she will examine evidence for treeline movement and how recent fires have impacted on the position of the treeline.

 

 

Left photo: Lauren testing her novel seed traps at Falls Creek. Right photo: Aviya and supervisor John Morgan examining treelines on the Bogong High Plains.

Recent RCAAE Journal Publications

John Morgan & Susanna Venn have modelled the dispersal capacity of most of the alpine flora of Kosciuszko (198 species).  They found that most species are predicted to have short-distance dispersal (<10m). This highlights the limited ability of Australian alpine flora to disperse and track rapid climate change.

Morgan, J. W., & Venn, S. E. (2017). Alpine plant species have limited capacity for long-distance seed dispersal. Plant Ecology218(7), 813-819.