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


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.


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.


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.


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.

National Expert Elicitation Workshop


The RCAAE recently hosted a National Expert Elicitation Workshop at La Trobe University (19-21 June 2017) examining the adaptive capacity and functional importance of alpine flora in the face of climate change.

Lead by an expert elicitation facilitator (Anca Hanea, University of Melbourne), workshop participants scored a range of alpine species for their present (2017) and future (2050) vegetative cover, a surrogate for functional importance and adaptive capacity. Participants also began the process of assembling a long-term alpine plot database that could be used to track change in species distribution and cover.