Nearly half of all tree species in the Amazon rainforest may be globally threatened, but there may still be hope if Amazonian land is properly managed.

Forest cover in the Amazon has been steadily declining since the 1950s, but there had been little research done on how this phenomenon affects individual species, the Field Museum reported. To fill in some of these research gaps, a team of scientist compared data from forest surveys across the Amazon with maps of current and projected deforestation to pinpoint which species had been lost and where. They found 36 to 57 percent of the Amazon's estimated 15,000 tree species are globally threatened under IUCN Red List of Threatened Species criteria.

"We aren't saying that the situation in the Amazon has suddenly gotten worse for tree species," said Nigel Pitman of The Field Museum. "We're just offering a new estimate of how tree species have been affected by historical deforestation, and how they'll be affected by forest loss in the future."

The researchers noted that some trends observed in the Amazon rainforest persists throughout the tropics, which could mean more than 40,000 tropical tree species are globally threatened. On the other hand, protected areas and indigenous territories now make up over half of the Amazon Basin, and contains significant numbers of most of these threatened tree species.

"This is good news from the Amazon that you don't hear enough of. In recent decades Amazon countries have made major strides in expanding parks and strengthening indigenous land rights said Hans ter Steege of Naturalis Biodiversity Center in the Netherlands. "And our study shows this has big benefits for biodiversity."

There is hope for tropical trees, but researchers are concerned the parks will only help save these threatened tree species if no further degradation occurs. Amazonian forests and reserves are threatened by a wide variety of factors, including dam construction, mining, wildfires, droughts caused by global warming, and human destruction.

"It's a battle we're going to see play out in our lifetimes," said co-author William Laurance of James Cook University in Australia. "Either we stand up and protect these critical parks and indigenous reserves, or deforestation will erode them until we see large-scale extinctions."

The findings were published in a recent edition of the journal Science Advances.