The Silvertop Project

Recent studies have found that disturbance from fire and logging can alter forest tree species composition, and this can have detrimental effects on habitat quality for folivores like the greater glider. In parts of north-eastern Victoria, as well as south-eastern New South Wales, recurrent natural and human disturbances are leading to a predominance of disturbance adapted tree species such as Silvertop Ash (Eucalyptus sieberi). Silvertop Ash seeds prolifically after fire and also tends to increase in abundance after logging due to a resilient seed bank and the ability to coppice. Unfortunately, it is usually very poor quality food for marsupial folivores like Greater Gliders and Koalas. As a result, forests that are dominated by this tree create green deserts that typically cannot support populations of these animals. The loss of diversity in tree species when Silvertop Ash becomes dominant also causes habitat loss for other wildlife and a substantial reduction in overall biodiversity.

Restoring the nutritional landscape

A collaborative project between researchers from The Australian National University and landscape restoration experts at Envite Environment will establish a series of critical new experiments to identify methods to restore the nutritional landscape by re-establishing forest composition of suitable eucalypt food tree species for the Greater Glider. We plan to do this by selective thinning to reduce Silvertop Ash regrowth in recently logged forest stands. The most effective stage to conduct these trial studies are young forests where the removal of Silvertop Ash saplings will be most straight-forward. Using a combination of hand-planted seedlings and direct seeding, we will revegetate the trial plots with locally appropriate eucalypt species that typically have higher nutritional quality than Silvertop Ash for a variety of eucalypt leaf eating animals. We will continue to revisit these plots periodically to suppress weeds, remove silvertop coppice regrowth, and monitor the survivorship of other eucalypt species and overall changes to vegetation composition over time. This work will entail close partnerships with key stakeholder and natural resource managers including Traditional Custodians, the Victorian Government Department of Land Water and Planning, VicForests, and local Landcare groups. 

The initial design phase for this project commenced in 2021 and the implementation of the field experiment component of the project is planned for 2022. The work will then continue until the middle of this decade and hopefully longer to ensure that suitable changes in tree species composition and nutritional quality can be achieved. Allied with the on-the-ground thinning experiments, we also will complete simulation modelling of nutrient landscapes based on different proportions of locally appropriate tree species. This will help us to understand the impact that various changes in tree species composition have on the overall nutritional landscape for folivores, like the greater glider. In the near future, we plan to upscale this restoration work to a few larger plots where we can incorporate our learning from the initial work and increase our capacity for the larger scale remediation that will be necessary to have substantial positive impacts on greater glider populations and overall biodiversity. In the larger plots, silvertop will be replaced with a compositon and proportion of eucalypt species that closely matches nearby forest areas with resident Greater Gliders.

This is a world-first study aimed at restoring nutrient landscapes for a key species of conservation concern. There will likely be many challenges associated with this novel yet important work. On this basis, the research team at The Australian National University would welcome feedback and insights from stakeholder groups and others with interests and expertise in wildlife conservation, forest management and eucalypt ecology. 

Watch The Silvertop Story below to learn more about why these landscapes need our help