‘Act early, act local’ to avoid ecological ‘tipping point’
Two La Trobe University scientists are part of a national effort that has helped identify Australia’s ten most highly-threatened environments.
A campaign based on this work, launched today, is urging Australians to ‘act early, act local’ to save large tracts of important landscape before they reach ecological ‘tipping point’.
The scientists are Dr Ben Gawne, Director of the Murray-Darling Freshwater Research Centre, a specialist on aquatic ecosystems, and Dr Ewen Silvester, Deputy Head of Environmental Management and Ecology and Director of the Research Centre for Applied Alpine Ecology.
Both are based on the Albury-Wodonga campus.
They are part of a team of 26 leading ecologists from Australia’s Innovative Research Universities whose work ‘The 10 Australian ecosystems most vulnerable to tipping points’ has just been published in the international journal ‘Biological Conservation’.
‘In ecological terms,’ says Dr Gawne, ‘a tipping point is a threshold beyond which an ecosystem may change rapidly and irreversibly into alien landscape, often dominated by introduced or unfamiliar species.
‘It often happens quite fast, for example when a wetland is highly fragmented by agriculture and other human activities, or damaged coral reefs become infested by seaweeds, or a rainforest is destroyed by fire.
‘When this occurs, it’s very difficult – if not impossible – to restore the original natural system,’ he says.
Landscapes our grandchildren may never see
‘It means that, unless we act with speed and decision, there are Australian landscapes today which our grandchildren will never get to see.’
Dr Gawne says the wetlands and floodplains of the Murray-Darling Basin are very vulnerable to tipping points. Apart from agriculture and other human activities, they face increased stresses from long periods of drought, invading plants and fish.
They also depend on a relatively small number of ‘framework species’, such as river red gums, many of which are struggling to survive.
The report notes: ‘The southern half of the Basin is at risk of further drying under climate change. We consider the most threatened areas, however, are those with acid-sulphate soils – which can send flushes of toxic water along creeks and rivers. The Coorong is also at high risk of tipping permanently to a highly saline state.’
Some of the remedies advocated include reconnecting the river to natural bushland and floodplains, reducing land clearance, allocating more water for natural ecosystems and river flow, removing redundant weirs, and installing fish ladders on those that remain.
Dr Silvester says mountain ecosystems are threatened by global warming, fire and various human impacts. Those of the Great Dividing Range, Tasmania and southwest WA are especially vulnerable to climate change which may bring warmer and drier conditions, loss of snow cover, more fires and invasive pests.
Mountain ecosystem under greatest threat
The report says mountain animals will be under growing threat as their habitats shrink and fragment and competition from outside animals increases. Tipping points will be reached here sooner than almost anywhere else.
Proposed countermeasures include re-establishing ‘corridors’ to link forest remnants, conserving threatened habitats as long as possible, relocating nature reserves to increase their resilience to global warming, and if possible, relocating some declining species to cooler areas.
Drs Gawne and Silvester say while some of these changes are global – many are also local – and can be mitigated by well-planned local action.
The study lists the ten landscapes, and the threats they face, in the following order:
• Mountain ecosystems: threatened by global warming, fire and human impacts.
• Tropical savannas: invasive plants and animals, huge bushfires, extreme events.
• Coastal mangroves and wetlands: sea-level rise, human development and climate change.
• Coral reefs: ocean warming, ocean acidification, overfishing, coastal runoff.
• Dry rainforests: changing fire regimes, hotter temperatures, water regime changes.
• Murray-Darling Basin: overexploitation, water regime changes, salinisation.
• Southwest forests and sand plains: water regime changes, hotter conditions, extreme events.
• Offshore islands: invasive plants and animals, extreme events, ocean changes.
• Temperate eucalypt forests: hotter temperatures and changes in fire and water regimes.
• Mangroves and salt marshes: hotter temperatures, rising sea-levels, water regime changes.
Full details of the study:
Protecting Australia’s most endangered landscapes
Main photo: Arthur Mostead, Murray-Darling Basin Commission