Tropical Forests Surrender Secrets in a Boost for Biodiversity

In a boon for conservation under climate change, scientists have found half of all tropical trees belong to just a few species – making it easier to monitor tropical forests.

James Cook University’s Distinguished Professor William Laurance was part of a major international collaboration of 356 scientists led by University College London (UCL). The researchers found almost identical patterns of tree diversity across the world’s tropical forests.

The study of over one million trees across 1,568 locations, published in Nature, found that just 2.2% of tree species make up half of all the trees in tropical forests across Africa, the Amazon, and Southeast Asia. These three regions are similar, with each having a few relatively common species and many rare species.

“We estimate that just 1,053 relatively common species account for half of the planet’s 800 billion tropical forest trees,” said Professor Laurance.

“Beyond this, there are many rare tree species in the tropics, perhaps 40,000 species in total. But these species are so rare they’re notoriously hard to study and conserve,” said Laurance.

Laurance said while tropical forests are famous for their diversity, this study reveals underlying similarities among different forests—despite being separated from one another by thousands of miles. But the specific reasons for the similarities remain unknown.

Lead author Dr Declan Cooper (UCL Geography and UCL Centre for Biodiversity and Environment Research) said the findings have profound implications for understanding tropical forests.

“If we focus on understanding the commonest tree species, we can probably predict how the whole forest will respond to today’s rapid environmental changes. This is especially important because tropical forests contain a tremendous amount of stored carbon, and are a globally important carbon sink.

“Identifying the prevalence of the most common species gives scientists a new way of looking at tropical forests. Tracking these common species may provide a new way to characterise these forests and, in the future, possibly gauge a forest’s health more easily,” said Dr Cooper.

This collaboration across hundreds of researchers, field assistants, and local communities resulted in a total of 1,003,805 trees sampled, which included 8,493 tree species, across 2,048 hectares, equivalent to almost eight square miles of forest.

The teams inventoried 1,097 plots in the Amazon totalling 1,434 hectares, 368 plots in Africa totalling 450 hectares, and 103 plots in Southeast Asia totalling 164 hectares. This research was supported by the Natural Environmental Research Council.