The globe's forests have shrunk by an area equivalent to the size of South Africa since 1990 despite efforts to conserve over the past decade, according to a recent study.

A report released last week by the UN's Global Forest Resources Assessment (GFRA) revealed that while the pace of forest loss has slowed, the damage over the past 25 years has been considerable. Total forest area has declined by three percent between 1990 and 2015 from 10,200,510 acres to 9,881,744 acres - a loss of nearly 319,000 acres.

Significantly, loss of natural forested area was double the global total at six percent, while tropical forests took the hardest hit with a loss rate of 10 percent. Agricultural land development, by large and small scale producers, is believed to be the main driver behind the decreases, with Brazil, Indonesia and Nigeria recording the biggest losses over the past five years.

"These are not good stats," Professor Rod Keenan, forestry expert at the University of Melbourne, said of the latest report. "We really need to be increasing forest area across all domains to provide for the forest benefits and services of a growing population. So there is more work to do."

But there have also been positive signs.

While the annual rate of net forest loss in the 1990s stood at about 18 million acres, it has since halved to more than 8 million acres between 2010 and 2015.

"Halving the loss is a good thing, but we need continued policy focus to ensure the trend can be sustained," Keenan said.

He said this should include regulations to stop forest conversion, funding for better forest management and incentives to increase forest area.

Brazil and Indonesia, both among the highest deforestation offenders, have significantly improved their ways -- with Brazil's current net loss rate 40 percent lower than in the 1990s. Indonesia is also losing forested area at a rate two-thirds slower than it did between 1990 and 2000.

Professor Keenan said the study showed forest is being more rapidly lost in some of the poorest countries, including India, Vietnam and Ghana.

"In low-income countries with high forest cover, forests are being cleared for direct subsistence by individuals and families and large scale agriculture for broader economic development," he said. "Some have policies and regulations to protect forests, but they do not have the capacity and resources to implement them."

The findings are detailed in the journal Forest Ecology and Management.