Fire in the snow: Thirsty gum trees put alpine water yields at risk

Posted 11 January 2007

Climate change could have radical effects on Australia's alpine regions. New predictions are that by 2050 virtually no snow will fall on the Snowy Mountains. Bushfires will become more frequent and severe.

Aside from major ecological changes, UNSW researchers say an equally great worry is that water yields are likely to plummet, with serious consequences much farther afield, particularly for the Murray-Darling river system.

Not only will much less snow fall, but research shows that massive regrowth of gum trees after bushfires can sharply reduce surface run-off to rivers and dams for up to 30 years. A landmark study is now under way to monitor the complex interplay between water, soil, trees and fire in the high country.

"Australia's high country is crucial to water flows in the Murray-Darling Basin," says Professor Mark Adams, of the UNSW Laboratory for Ecosystem Science and Sustainability. "Water and hydro-electricity generated in the high country feed cities, agriculture and much of Australia's economy.

"The upper reaches of the montane forests, the sub-alpine woodlands, alpine grasslands and meadows in Victoria, NSW and the ACT are critically important. Snowmelt there currently provides one of the key insurances for water managers, an insurance that almost completely failed in 2006.

"Fire poses a major threat to the security of water yield from this region yet this threat remains poorly understood relative to other areas, such as the Sydney and Melbourne water catchments.

"Unchecked bushfires create large-scale forest regeneration that uses more water than the mature forests they replaced. Research shows that the 2003 fires, for example, will likely reduce flows by more than 20% for the next 20 to 30 years in the Kiewa River, a major tributary of the Murray.

"The way we manage these lands has important implications for present and future fire regimes. Grazing, in conjunction with prescribed fire, was previously used to manage large areas but these practices have been largely excluded from high country. Vast areas have been set aside in national parks for the single purpose of conserving biodiversity and the use of prescribed fire to manage fuel loads and fire hazards should be a major part of management practises in the region.

"The recent fires in Kosciusko National Park have highlighted yet again the vulnerability of montane forests to bushfire. It has been suggested that climate change is already responsible for major changes in vegetation."

A much better understanding of the complex interplay between climate, fire, plants, soil and water is needed to form the basis of sound land-management policies and practises in the Snowy, Professor Adams says.

"We've known for 100 years that the Murray River can dry up from time to time and we know a lot about how much water is flowing through the river, but we know precious little about what goes on up there at the source of the water in the high country."

The new $1.7 million High Country Fuels and Ecosystem Functions (HCFEF) research project aims to fill that knowledge gap. The project involves scientists from three Australian universities, the Bushfire Co-operative Research Centre, CSIRO and international institutions.

A large network of instruments has been set in place to monitor temperature, air, rainfall, soil moisture, carbon levels and even sap-flows in trees to directly measure the effects of seasonal and climate change.

The network includes automated water and carbon flux towers and weather stations at a wide range of sites embracing grasslands, montane forest and woodlands across the high country, including mature and regenerating bushland.

But Professor Adams is calling for more resources to be made available to ensure the project continues beyond 2008: "We need to be monitoring what's going on for at least 10 years to get useful results."

Contacts:
Professor Mark Adams, mark.adams@unsw.edu.au
UNSW Faculty of Science media liaison: Bob Beale 0411 705 435 bbeale@unsw.edu.au

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