Eucalyptus Gunnii - Skeleton
Past kings of the Tasmanian high plains these tree are in rapid decline due to warmer winters allowing grazing animals and insects to devastate the new growth.
The Plans and Maps
A GPS and maps featuring satellite images marked with the locations where the tree might possibly be found were necessary tools. Unmarked property boundaries, barbwire fences, snakes, sites hidden by thick tea tree scrub and the risk of getting injured or lost were all obstacles that required attention.
Reaching the Sites
Distances covered in a day reached 22km with tough terrain, poor weather and few results to speak of the survey was difficult going.
Weather during the day would rarely be considered ideal for field work. However, the work schedule was tight with few opportunities to stop for weather.
Eucalyptus Gunnii - Habitat
The prime habitat of Gunnii is the open plains of the Tasmanian high country where cold air pools. The process is call "cold air drainage" and the coldest temperature recorded during the survey was -9 Celsius. It is so consistently cold in these areas that no trees can grow, instead the plains are inhabited by hardy bushes and grasses.
Eucalyptus Gunnii - Habitat 2
The weather was relentless and few days were considered easy going. At times during the survey we would spend all day working in the rain which would mean us and our gear would be soaking. Managing the necessary scientific and photographic equipment during these times was incredibly difficult.
Eucalyptus Gunnii - Expired
Twisted and tangled expired trees dominate the plains near the town of Miena and for a very devastating impressions of this tree ultimate survival.
Eucalyptus Gunnii - Wilderness
Even in the pristine locations it's common to see a stand of trees in decline indicating that the cause of the decline was not based purely within the farmland environment.
Eucalyptus Gunnii - Sunrise
On occasion the sun did provide specular viewing opportunities for this remarkable tree. The locations we visited during the 25 day survey were remarkable in their untouched nature, we spend days wandering sites that might not have been visited in decades
Eucalyptus Gunnii - Cider
The sap of Gunnii is as sweat as honey and traditionally it has been used to make an alcoholic cider. There are unconfirmed reports that it was used by the local aboriginal people the same way.
Eucalyptus Gunnii - History
Many trees bare scars from where they were cut by Aboriginals in order to harvest the sweet sap. Some tree have successive scars up the height of the trunk indicating a long standing practice as the trees grew slowly over time.
Eucalyptus Gunnii - DNA Analysis
Once sighted all suspected specimens had botanical samples were taken for DNA analysis. It is very common for Eucalyptus trees to be very difficult to identify due to cross breading or local conditions producing stunted or discoloured leaves.
Eucalyptus Gunnii - Growth
Detail of the young shoots of Gunnii shows just how discoloured the new leaves can be making it difficult to identify. This style of new growth is called glaucus growth and is an adaptation to local conditions.
Eucalyptus Gunnii - Seeds
It was a rare chance to collect viable seed samples from the trees that we did find.
Eucalyptus Gunnii - Flower Closeup
During the entire 25 day survey only 2 trees were producing healthy flowers. This macro shot might be the best example of the tree flowers available.
Eucalyptus Gunnii - Survey
Ms. Sanger enjoys a fine day of field work under a newly discovered Gunnii
Eucalyptus Gunnii spp. Gunnii
Pristine, healthy and flowering. The best Eucalyptus gunnii spp. gunnii that we found during the survey.
Eucalyptus gunnii spp. gunnii or as its commonly known Miena Cider Gum is an endangered species of Australian tree endemic to the Tasmanian highlands coldest and most spectacular areas. For 25 days I documented the most comprehensive distribution study of the tree ever. The study was undertaken because of the rapid decline of the species over the last 30 years.
Gunnii is thought to be a climate change indicator species as it is the most frost tolerant Eucalypt species only growing on the boundaries of frost hollows in Tasmania’s highlands. Even in the middle of summer night time temperatures can regularly drop below -5 degrees Celsius and winter maximums rarely above 15. Gunnii manages to survive in these frost hollows because of its unique adaption of having a very sugar rich sap. Sugar is a natural anit-freeze so while the other eucalyptus in the area are at best dormant Gunnii thrives, or at least that's the evolutionary idea.
However, more than 60% of the know population of this tree has expired in the last 30 years with the primary cause being global climate change. Long droughts followed by warmer winters are the primary cause of its rapid die back as well as the impacts on soil from sheep and cattle grazing in the area. With much of Gunnii's theoretical distribution laying inside private land owned by Gunns, Tasmania’s biggest logging company, its true numbers were highly speculative and until this survey largely unknown.
The vast majority of the known population is in close proximity to the town of Miena 140km from Hobart hence is common name the Miena Cider Gum. The other half of the name "cider Gum" refers to historical accounts of its unusually sweet sap being fermented and drunk as an alcoholic beverage by local aboriginal groups. Exacting scientific accounts of its traditional alcoholic use are nonexistent but there is abundant hard evidence that they did at least harvest the sap. I had the opportunity to taste the sap straight from the trunk of a tree we discovered during the survey and it is as sweet as honey but with a slight eucalyptus flavour.
While the population close to Miena has has been carefully studied the properties further into the wilderness owned by Gunns have never been surveyed due to Gunns obvious economic interest in not knowing. However the recent acquisition of many of Gunns properties by the Tasmanian Land Conservancy (TLC) allowed ecological scientists access for the first time. These photos are from that first round of surveys covering 63 sites on 7 different properties and covering a very large area of the Tasmanian highlands.