The Lal Lal Landcare Group, the University of Ballarat, and the Warrenheip and Dunnstown communities have been working with Parks Victoria over the past 18 months to try to establish the cause of tree dieback on the Ballarat landmark.

Undergraduate student Rachael Martin has conducted the research and data analysis with aerial surveys and ground assessments.

Working with the volunteers, Ms Martin has found the cause to be a combination of factors.

"Above-average temperatures, below-average rainfall and the hot northerly winds we have experienced in recent years - these factors, together with reduced soil moisture, have all combined to reduce water availability to the trees and many have died," Ms Martin said.

"This has been especially so on the hotter northerly aspect of Mt Warrenheip where more trees have died."

Rachael also found that groundwater monitoring bores in the Mt Warrenheip area have fallen by between seven and 10 metres, with much of the fall in groundwater levels occurring in the very dry 2006 year.

"This may be an added factor as the tree roots can no longer reach the groundwater table," she said.

Parks Victoria ranger Mathew Sobey acknowledged the hundreds of volunteer hours spent in the field collecting data.

"It has been amazing to work with such passionate volunteers," he said.