According to campaign website Forests.org, 42,793 people from 79 countries had emailed a copy of a letter to Prime Minister Julia Gillard, federal Environment Minister Tony Burke and Australian embassies by last night.

Huon Valley Environment Centre and Still Wild Still Threatened launched the campaign late last week, with protester Miranda Gibson vowing to stay in her tree-sit until Forestry Tasmania withdraws from coupes within the World Heritage nominated area.

The letter names stopping logging in Butlers Gorge as a priority.

Last week Forestry Tasmania managing director Bob Gordon told a parliamentary inquiry that there were eight or 12 coupes in the nominated area scheduled for logging in the next six months.

"There's a process that is being worked through to see how many of those can be rescheduled," he said.

Meanwhile, a study commissioned by Forest and Wood Products Australia has found that properly managed production forests maintain a similar level of biodiversity to largely undisturbed landscapes.

The research, carried out by Forestry Tasmania and the University of Tasmania, found that tall eucalypt forests did not need to be in reserves to provide habitat for animals or plants.

Forestry Tasmania principal scientist Tim Wardlaw said the study showed that timber could be harvested without destroying biodiversity values, particularly if that was integrated with areas containing mature forests.

"There has been a shift of thinking in conservation science over the past decade," Dr Wardlaw said.

"It's now considered best practice to mix harvesting and retention across wider areas."