"Twenty years ago, we had almost no information about how to build a forest," said Jefferson Hall, staff scientist at the Smithsonian Tropical Research Institute.
"People either planted one of four non-native species -- teak, pine, eucalyptus or acacia -- or they used a trial-and-error process with other species that was not always successful.
"Now we can be smart about which trees we plant at a given site, and we understand much more about what motivates land owners and rural farmers to put this know-how to work."
Forests keep water clean, control soil erosion, store carbon, shelter animals and provide plants that offer pharmacological benefits, a Smithsonian release said Monday.
"Now the science behind tropical forest restoration is at a level of sophistication that reforestation projects can be planned to target multiple goals -- to store carbon, manage water and conserve biodiversity, buffer old-growth forests from destruction and provide a strong return on investment," Eldredge Bermingham, director of the Smithsonian Tropical Research Institute, said.
Scientific reforestation is especially necessary in a world where half of the tropical forests are secondary forests growing on abandoned farm and pasture land, Smithsonian researchers said.