Just 2% of rainforest tree species account for 50% of the trees found in tropical forests across Africa, the Amazon and Southeast Asia, a new study has found.
Following patterns found elsewhere in the natural world, researchers have discovered that a few tree species dominate the world’s most important rainforests, with thousands of rare species making up the rest.
Led by University College London researchers and published in the journal Naturethe international collaboration of 356 scientists discovered almost identical patterns of tree diversity across the world’s rainforests, which are the most biodiverse places on the planet. The researchers estimate that just 1,000 species account for half of the Earth’s 800 billion trees in tropical rainforests, with 46,000 species making up the rest.
“Our findings have profound implications for understanding tropical forests. If we focus on understanding the most common tree species, we can probably predict how the whole forest will respond to today’s rapid environmental changes,” said lead author Declan Cooper, from the UCL Center for Biodiversity and Environmental Research. “This is particularly important because tropical forests contain a tremendous amount of stored carbon and are a globally important carbon sink.”
The team of scientists showed that while African tropical forests have fewer species compared to the Amazon and Southeast Asia, their diversity follows the same pattern. The analysis is based on more than 1 million tree samples across 2,048 hectares (5,050 acres) of rainforest at 1,568 locations. They found that about 2.2% of species made up 50% of the trees across the biome.
Prof Bonaventure Sonké from the University of Yaoundé I in Cameroon, said: “The fact that African forests do not have as many species compared to Amazonian and Southeast Asian forests is well known, but we also find that they have the same ratio of species that are common, indicating the existence of fundamental rules to which all the world’s tropical forests conform.”
Researchers said the findings suggest a mechanism may control the composition of all the world’s tropical forests. They plan to focus future work on identifying the potential rule, given the geographic differences of the forests they studied. African tropical forests experience a drier, cooler climate than the other two regions, while those in Southeast Asia are spread across disconnected islands. The Amazon is a large region of connected forests in which people live for a shorter time than the other regions.
The senior author, Prof Simon Lewis from UCL’s School of Geography and the University of Leeds, said: “We wanted to look at tropical forests in a new way. Focusing on a few hundred common tree species on each continent, rather than the many thousands of species we know almost nothing about, can open up new ways of understanding these precious forests.
“This focus on the most common species should not take away the importance of rare species. Rare species need special attention to protect them, but rapid and important knowledge gains will result from a scientific focus on the most common tree species.”
