By Considine, Mary-Lou
Ecos , No. 160
Time is fast running out for one of Australia's most charismatic marsupials, the threatened mountain pygmy possum (Burramys parvus). This delicate animal is only found within a 3-4 sq km area of the Australian Alps where it hibernates in winter under snow. Modest though its habitat may be, the species' range is set to shrink rapidly this century if global warming continues at its current rate.
How can we help this animal adapt to a changing climate and habitat? If snow cover all but disappears, there will be no opportunity to create a protected habitat corridor--an 'emergency exit'--for B. parvus to retreat to.
Its best chance of surviving in the wild, say some scientists, is to move small populations to a new 'home' in forested areas below the snow-line--outside the species' current range. The basis of this proposal is evidence from the fossil record showing B. parvus was once widespread at lower altitudes (see p 12).
'Option of last resort'
Moving species for conservation purposes is not new. More than 200 translocations and reintroductions of 42 vertebrate species have been carried out in Australia since European settlement.
However, all relocations to date have been carried out in response to tangible threats such as introduced pests or diseases, stock grazing, land clearing or hydroelectricity works. Under current environmental regulation --particularly the federal Environmental Protection and Biodiversity Conservation (EPBC) Act 1999--there is no provision for relocating species in response to climate change.
Yet scientists point out that the unprecedented speed of anthropogenic climate change will outpace the adaptive capacity of many species. Rapid climate change has already caused changes to distribution of many plants and animals, leading in some cases to extinctions. And scientists predict entire ecosystems such as cloud forests and coral reefs could disappear by the end of the century.
Late last year, the Terrestrial Biodiversity Adaptation Research Network, funded through the National Climate Change Adaptation Research Facility (NCCARF), ran a workshop at which ecologists and policy makers debated the environmental, ethical and policy aspects of managed relocation. (1)
Workshop participants concluded that managed relocation (2) 'is not a panacea to climate change adaptation for biodiversity and is pointless without a substantial commitment to mitigation, ongoing management of existing threats and a belief in the community that biodiversity can and should be conserved'.
Macquarie University's Professor Lesley Hughes--a Commissioner with the recently established Climate Commission, and a co-convenor of the Terrestrial Biodiversity Adaptation Research Network--agrees the approach should be seen as an 'option of last resort'.
In an earlier collaboration, Prof Hughes was involved in developing a broad risk assessment framework for policy makers and conservation agencies that begins with more conventional options for conserving species. (3) This emphasis on conservation in situ acknowledges the risk of managed relocation becoming a 'distraction' from climate change mitigation and habitat protection efforts.
Using the framework, managers would first evaluate opportunities for reducing the level of non-climate impacts--such as pests, weeds, frequent fire or habitat degradation--on the species. 'We simply need to do a lot better at managing existing, long-term threats,' says Prof Hughes.
The next step would be to assess the potential for species to move 'under their own steam' into new climate zones via habitat corridors carved out of the landscape.
'That's not going to fix everything because most species don't move far enough each year to keep up with the rate of climate change,' explains Prof Hughes. 'For some species there may be other things you could do in situ. …