Spanning the continental divide, near the border of Panama and Costa Rica, is the cloudiest place in Central America: the Fortuna Hydrological Reserve, a tropical highland forest with almost as many tree species as the entire United States. New species and important new information about carbon storage from this tiny area—19,500 hectares/75 square miles—of nearly-intact wilderness continue to surprise researchers from the Smithsonian Tropical Research Institute, who have been studying Fortuna’s vegetation, soils, insects, microbes and amphibians for several decades.

STRI research associate Jim Dalling, an ecologist at the University of Illinois-Urbana Champaign, has explored Fortuna’s montane forest for 25 years. In an effort to understand how environmental factors determine the distribution of plant species in tropical mountains, he measured the growth rates of over 30 thousand trees across a variety of soil conditions.

“There are 891 tree species, which is 30 percent of the species in all of Panama,” Dalling said, during a recent STRI webinar. “Throughout the USA there are 950 species of trees. This diversity is due to extreme variation in climate. The mix of lowland and highland species generates more diversity.”