First family tree for tropical forests

An international team of researchers, including Indians, unravels their evolutionary history

Scientific conservation: Five major forest regions have been identified in the tropics: the Indo­Pacific, Subtropical, African, American and Dry forests.

They may be oceans apart, but tropical forests in different continents across the world are related and share a common ancestry, according to a team of more than 100 researchers, including several Indian scientists.

The discovery, published on February 5 in the international journal Proceedings of the National Academy of Sciences , necessitates a new classification system for plant communities, which could help researchers predict the resilience or susceptibility of different forests to global environmental changes more accurately.

Million tree samples

To classify tropical forests based on their genetic relationships, scientists contributed almost one million tree samples of 15,000 species from tree plots across 400 locations in the world. Indian scientists from the Indian Institute of Science, Pondicherry University, Delhi University, Jawaharlal Nehru University, Bharathiar University, International Institute of Information Technology, Sigur Nature Trust (SNT) and the Kerala Forest Research Institute also contributed to this data.

Incorporating genetic information of these species, the team led by scientist Ferry Slik (Universiti Brunei Darussalam) built a family tree to see how these trees are related to each other through millions of years of evolution. With this, they identified five major forest regions in the tropics: the Indo-Pacific, Subtropical, African, American and Dry forests.

According to their results, tropical forests in Africa and South America are closely related, with most of the differences between them occurring within the last 100 million years. This likely reflects patterns of plate tectonics, as South America and Africa broke apart resulting in the formation of the Atlantic Ocean that started approximately 140 million years ago.

Another finding is that dry forests found in India, America, Africa and Madagascar are also closely related to each other.

“India plays a central role in this story because many of the plant species in the Asian tropics reached Asia via India about 45 million years ago, including the very important tree family of Dipterocarpaceae (Asia’s main timber group),” Slik wrote in an e-mail to The Hindu .

“In terms of fundamental science, these are important results in botanical research,” said India-based ecologist Jean-Philippe Puyravaud of Masinagudi’s Sigur Nature Trust, who contributed to the study. “Forests and vegetation are uniquely shaped by their history, and we need to make more efforts to conserve them.”

According to the authors, different forests may be more vulnerable or resilient to climate change and deforestation, so understanding similarities and differences between forests will help inform conservation efforts.