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Blue gum mapping a team effort

Brad Potts and Paul Tilyard
University of Tasmania

Figure 1. Paul Tilyard (UTAS/CRCF, right) and GIS specialist Winston Smith (DPIPWE, left) review some Eucalyptus globulus distributional records

A collaboration among several CRC partner organisations has resulted in a new distribution map of Eucalyptus globulus (Tasmanian blue gum) in Tasmania (the species also grows in Victoria). The review was requested by The Fauna Strategic Planning Group (Technical Working group) that was developing Swift Parrot habitat management guidelines. Eucalyptus globulus forest is important habitat for the endangered Swift Parrot (Lathamus discolour; Psittacidae) as the large flowers of E. globulus are a major source of food (nectar and pollen) for the birds when they migrate into Tasmania for breeding (Hingston et al. 2004a, Hingston et al. 2004b).

Figure 2. The distribution of the 8,126 E. globulus point records compiled from electronic sources.

The distribution of E. globulus had not been updated formally since 1996 (Williams and Potts 1996) and because E. globulus has been planted widely for plantation forestry and other purposes -  and some of the records in electronic data bases were beginning to include planted populations - it was important to clarify the natural distribution of the species. Hence, 15 years' worth of data that had accumulated since the last distribution assessment were compiled and reviewed.

The work was undertaken by staff from the Threatened Species Section of the Department of Primary Industries, Parks, Water and Environment (DPIPWE), the Forest Practices Authority, Forestry Tasmania and University of Tasmania (Figure 1).

The team obtained and reviewed point records from numerous electronic sources including the Tasmanian Natural Values Atlas, the Tasmanian Herbarium and records from the above organisations to update the electronic data used by Williams and Potts (1996).  Availability of modern GIS tools (e.g. Google Earth) was a quantum improvement to the screening process compared to the map-based verification used in the mid-90’s. The final screened data set of 8,126 E. globulus point records (Figure 2) complements old and new vegetation mapping undertaken by DPIPWE for the natural distribution for wet, dry and subdominant E. globulus forest.

The review highlighted the recent discovery of an extensive E. globulus population on the west coast of Tasmania between the previously recorded small stands at Little Henty River and Badgers Creek (Figure 3).  A previously unknown E. globulus forest was discovered by Richard Barnes and Colin McCoull (SEMF Pty. Ltd.) during environmental surveys in the Trial Harbour region commissioned by a wind farm company.  Subsequent aerial surveys for Wedge-Tailed Eagle nests (Figure 4) by Bill Brown (Threatened Species Section, DPIPWE) provided further distributional information on E. globulus in the area. The aerial survey data were integrated by SEMF Pty. Ltd. with the on-ground mapping data of Barnes and McCoull to produce an approximate distribution map of blue gum dominated forest between Little Henty River and Badgers Creek .  While E. globulus is widely distributed in eastern Tasmania, its distribution in western Tasmania is clearly disjunct (Figures 2 & 3). The western populations are genetically differentiated from the E. globulus in eastern Tasmania and have closer molecular affinities to the E. globulus on King Island (Steane et al. 2006).

Figure 3. The newly discovered large population of E. globulus on the west coast of Tasmania occurs between two previously known small populations at Little Henty River and Badgers Creek (circled).  Point records of E. globulus are shown in red.  The blue indicates other areas where E. globulus is thought to occur but further on-ground validation is required to delimit the exact distribution of the species in this area.

Hingston AB, Gartrell BD, Pinchbeck G (2004a) How specialized is the plant-pollinator association between Eucalyptus globulus ssp. globulus and the swift parrot Lathamus discolorAustral Ecology 29: 624-630.

Hingston AB, Potts BM, McQuillan PB (2004b) The swift parrot Lathamus discolor (Psittacidae), social bees (Apidae) and native insects as pollinators of Eucalyptus globulus ssp. globulus (Myrtaceae). Australian Journal of Botany 52: 371-379. [read]

Steane DA, Conod N, Jones RC, Vaillancourt RE and Potts BM. (2006) A comparative analysis of population structure of a forest tree, Eucalyptus globulus (Myrtaceae), using microsatellite markers and quantitative traits. Tree Genetics and Genomes 2: 30-38. [read]

Williams KJ and Potts BM (1996) The natural distribution of Eucalyptus species in Tasmania. Tasforests 8: 39-165. [read]

Biobuzz issue thirteen, December 2010


Figure 4. A wedge-tailed eagle nest in newly discovered E. globulus forest, south of the Little Henty River, on the West coast of Tasmania (photo: Bill Brown, Threatened Species Section, DPIPWE).