Natural high for Earthwatch helpers
	Pet project: An Earthwatch volunteer with a Mountain Brushtail Possum, one of the species being studied
By Julian Lee An ANU ecology project in Victoria is offering hundreds of volunteers the chance to participate in a scientific study while taking a break in the bush. Volunteers from around the world have been involved with Earthwatch - a community based conservation program - to study possums in a remote and inaccessible region of Victoria. The Leadbeater's Possum is a small tree-dwelling marsupial found only in tall mountain forests in Central Victoria. It is endangered and in the first half of this century had been thought extinct until it was rediscovered in 1961. Earthwatch volunteers spend 12 days in the forests recording the numbers and whereabouts of the possum, and other endangered species. Head of the project, Dr David Lindenmayer of the Centre for Resource and Environmental Studies (CRES), is forecasting a drastic decline in the Leadbeater's Possum due to natural tree fall and logging by clearfelling. "The possum population will collapse by 90 per cent over the next 20 years if the current situation remains," he said. Dr Lindenmayer has been studying the ecology of this area for over 15 years and has published more than 100 papers on the subject. "When you measure hundreds of sites, you get an idea of their habitat - where they live and why," he said. He has found that only a small fraction of the forest is suitable for each type of possum. "The Leadbeater's possum likes mixed-age forests with lots of massive old trees - two to three metres in diameter - with hollows and a dense understorey," he said. "This means that quite a large forest may only be able to support a relatively small population of possums." The dense understorey and the Leadbeater's possums' nocturnal movements make them hard to survey by the usual method of spotlighting. "In order to get an accurate estimate of the number of possums, all the trees and hollows need to be stationed at the same time," he said. To recruit the number of people needed to do this, Dr Lindenmayer instigated the community-based monitoring program. "It is a combination of a rigorous scientific framework and community involvement. No one scientist could do the monitoring on his own," he said. Each of the volunteers is assigned a tree where they sit for two to three hours at dusk and record the different types and numbers of possums. During the day the volunteers investigate the structure of the forest including measurements of log sizes, ground cover and tree types. "The volunteers learn many new skills and the knowledge that they are contributing to meaningful science," he said. "They discover what the scientific research process involves and where taxpayer's money is spent." While the monitoring program will reveal whether or not the possum population is declining, the information gathered will also assist in finding ways of balancing the needs of timber for humans and habitat for animals. For example, Dr Lindenmayer suggests that by letting some of the old trees remain after each logging, the possums' habitat could be preserved. "Even if you cut every 80 years, you don't get the really old trees that many species require." He argues that the demise or survival of the Leadbeater's possum is a test case for sustainable forestry. "If we can't preserve the Leadbeater's possum, then there is no way we can claim we manage our forests sustainably," he said.