Oliver Medd – u6702346
A team of Masters student researchers at the ANU are working to find the answers to the cause of a dieback event, affecting snow gums in the Snowy Mountains region of NSW, and how to properly save the iconic local flora.
The Snowy Mountains of New South Wales are a region rich in Australian poetic history. The rolling snowy peaks and crystal streams are experienced by many bushwalkers, skiers, snowboarders, mountain bikers and holidaymakers both from around Australia and globally year-round. However, there is a noticeable change occurring within the peaks. Large deaths of the snow gum forests within Kosciuszko National Park are turning landscapes from green canopies to skeletons of bare wood.
Masters researcher Jessica Ward-Jones, is looking to find the answers to the cause of the current dieback event in the Snow Gum populations within Kosciuszko National park, and where it is occurring.
The Snow Gum (Eucalyptus pauciflora), more specifically the sub-species niphophila, are the highest growing trees in Australia, growing around the snow line within the park at around 1600 to 1900 meters in altitude. Their presence within the park increases the water yield taken from the atmosphere, influencing the health of the understorey and wildlife within the area. Due to their location, the Snow Gum is adapted to high rainfall and soil moisture content, therefore the tree’s drought tolerance is very low.
Two factors are thought to be influencing the current dieback event in Snow Gum populations around the Snowy Mountains. The first factor is thought to be drought and the increasing frequency and intensity of hotter, drier periods in the area. These conditions reduce the available water intake for the tree species and cause stress. The second factor is the Longicorn beetle, part of the Phoracantha genus. These are wood-borer beetles that are native to Australia, feeding on the tissue under the bark of stressed trees. The beetles feeding habits forms trench-like galleries which eventually cut off nutrient supply and effectively ‘ring-bark’ the tree. The two factors are closely related in the presence of dieback, as the stress in the snow gum trees during drought increases their vulnerability to attack from longicorn beetle.
Jessica, fellow researchers, honours supervisor Prof. Matt Brookhouse and a team of volunteer researchers (including myself) travelled to Kosciuszko National Park mid-December of 2019 to collect data on the occurrence of Snow Gum dieback. Data on the presence of Longicorn beetle damage and spatial data on the location and conditions correlating with the presence of tree death was collected. The data was spatially logged using portable computers linked to GPS, with pre-determined transects followed and data taken at consistent points along each transect. Each tree, within a radius of each point, was recorded for their size, general health, and any evidence of beetle damage.
In total, 2315 trees were measured, and the data produced some interesting results.
Probability of Dieback presence in relation to slope and elevation – Jessica Ward-Jones
The results suggest that the presence of dieback in the snow gum communities within the park was stronger on steeper slopes at lower altitudes where conditions were less favourable to snow gum growth. This suggested the dieback affects already more stress prone trees to a greater extent. Also, it was found that slopes with an easterly aspect show higher evidence of dieback in snow gum trees.
Other influences on the presence of dieback were observed. Previously burnt communities of snow gum within the park showed a greater resistance to dieback, where the unburnt communities had a higher probability of dieback occurrence. The presence of ski resort parks also displayed correlation with dieback probability, with resort areas being more open and in historical stock grazing routes with less vegetation, more soil loss and compaction and thus more rainfall runoff observed.
The implications of the work done by Jessica and her colleges will provide better information to educate future dieback outbreak predictions within the Kosciuszko National Park, as well as other sites of similar dieback within Australia. Her findings will also work to improve and inform targeted management strategies to protect the snow gum communities within the park in the future.
An interview with researcher Jessica Ward-Jones about her work with the dieback in the snow gums community of the Snowy Mountains can be found here:
I’d like to thank Jessica for her time to talk with me about her research.
Biodiversity Conservation 