Category Archives: News

RCAAE ecologists highlight decline in high country Bogong Moths

RCAAE ecologists have, as part of their long-term monitoring, raised the alarm about the potential decline in Bogong Moths in the high country and it’s potential to negatively affect the critically endangered Burramys (Mountain Pygmy Possum).

Declines of this nature, of a common species, are likely due to drought in the moths breeding grounds. This highlights the need for better understanding of the ecology of Bogong Moths, especially in lowland landscape where they live and breed, and a better network of observation stations in the alps to understand temporal dynamics.

Watch this space for a citizen science initiative.

Read more:
https://www.abc.net.au/news/science/2019-02-27/bogong-moth-decline-in-australian-alps/10850036
https://www.theguardian.com/environment/2019/feb/25/decline-in-bogong-moth-numbers-leaves-pygmy-mountain-possums-starving

 

New Paper: Using leaf traits as barometers of change

leaftraitsScanned images that illustrate the diversity of leaves sampled in this study from 27 grassland sites. These very leaves were collected from sites located in Australia, Canada, United Kingdom, United States and Switzerland and brought together in this collage.

For decades, scientists have searched for a set of simple, easily measured traits that could be used to predict how plants respond to environmental change at any site around the world. These traits have been referred to as the ‘holy grail’ because they could serve as a standardized instrument, a biological barometer, to predict the effects of global change on the earth’s ecosystems.

In a recent Nature Ecology and Evolution paper, co-authored by RCAAE member Dr John Morgan and including data from the Australian Bogong alpine grassland site, we measured how some of these commonly used leaf traits respond to two of the most prevalent global changes, increased nutrient loading and altered grazing rates, across a set of 27 grasslands sites in four countries. These sites are part of a globally replicated experiment, the Nutrient Network, being conducted at over 100 sites around the world.

 Leaf nutrient concentrations (i.e. percent nitrogen phosphorus and potassium) increased in fertilized plots, which is consistent with ecological theory. However, this result is at odds with a well-known theory in agriculture called the growth-dilution effect which predicts the increased growth of the plants will outpace nutrient accumulation in the tissue. Contrary to existing ecological theory and expectations from physiological ecology, specific leaf area (SLA), perhaps the most widely-used leaf trait, did not show a consistent response to nutrient addition. We found no consistent changes in any of the leaf traits, which is contrary to expectations from plant-defense theory.

Why are leaf traits so important to plant ecologists?

The environment in which plants grow and the organisms that eat them can sculpt their features or ‘traits’ including the area, weight, and thickness of their leaves, the number of seeds they produce, the height they reach, and the amount and type of roots they grow. These traits, in turn, can determine the effectiveness of each species – and the combination of species in a location – in capturing energy from the sun or nutrients from the soil.

Ecologists use changes in leaf traits to compare plant growth strategies and subsequently infer how ecosystems function. Despite the high diversity of species globally, it is reasonable to expect that there may be consistent trait responses because all plants have much in common including their reliance on three essential resources, light, water and elemental nutrients, which sustain common functions of growth, reproduction, defense, and storage.

Plant ecologists use traits to discover commonalities, but leaf traits are also used more practically to understand the impacts of disturbance and for rebuilding plant communities in restoration efforts. The practical application of leaf traits to infer ‘function’ has been ongoing for decades without a global experimental test of whether leaf traits actually respond in a predictable way to short-term perturbations. Our experimental test helps to isolate cause from correlation in the relationship between plant function and plant traits. Leaf nutrient concentrations are useful as barometers of short-term nutrient enrichment, but not SLA. SLA still has its uses, a measure commonly used to distinguish plant defense-competition tradeoffs. It might be that SLA is less plastic and thus a complete species replacement is needed over the longer term in response to the treatments to detect a change.

The full paper led by Jenn Firn, Leaf nutrients, not specific leaf area, are consistent indicators of elevated nutrient inputs, can be found at http://dx.doi.org/10.1038/s41559-018-0790-1

 

RCAAE submission to the parliamentary inquiry into Australia’s faunal extinction crisis

The RCAAE welcomes this inquiry into Australia’s faunal extinction crisis and has made a submission highlighting the need to invest in long-term monitoring to track the status of threatened species populations. Such an investment is needed to inform appropriate management and ensure the persistence of Australia’s threatened species, such as the Burramys (mountain pygmy possum) and Guthega Skink.

Monitoring, performed over long time periods, is necessary to detect changes in population abundance, identify key threats and causes of decline, and to undertake effective adaptive management to reverse species decline. Almost nowhere else is this better illustrated than in the Australian Alps where long-term monitoring and management of threatened species has been undertaken for decades.

Chronic under-funding threatens the capacity to continue monitoring threatened species and undertake required management actions. A new Federal funding initiative is urgently needed in Australia to ensure that current long-term monitoring for threatened species is maintained, and to enable such monitoring activities to be expanded.

The full RCAAE submission can be found here.
All submissions made to the parliamentary inquiry into Australia’s faunal extinction crisis are accessible here.

 

burramys
The nationally endangered Mountain pygmy possum (Burramys parvus).

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.

specimens

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.