A tropical rainforest in the Ethiopian highlands.
Photo: © Christine Schmitt

Tropical forest diversity higher than previously assumed

People are fascinated by the amazing diversity of tropical forests and will be surprised to learn that there are possibly more than 53,000 tree species in the tropics, in contrast to only 124 across temperate Europe.

The earth is home to some 40,000 to 53,000 tropical tree species is the finding of a survey carried out by an international team of over 170 research scientists. As the scientists from the Albert-Ludwigs University of Freiburg, Germany, state in a mid-June press release, while it is generally known that tropical forests have a far higher biodiversity than temperate forests, no actual survey has yet been made of the number of tropical tree species in individual survey areas, and world-wide figures were only based on estimates. To obtain a systematic analysis of tree species diversity, researchers from all over the world have merged their data on the occurrence of species collected in tropical regions. The merged data set covered 657,630 individual trees and 11,371 tree species.

At the Albert-Ludwigs-University Freiburg, Germany, Dr. Christine B. Schmitt, Chair of Landscape Management and Dr. Juan C. Montero, Chair of Site Classification and Vegetation contributed to the study from vegetation studies carried out in the forests of Ethiopia, Brazil and Bolivia. „The study is a major milestone in the evaluation of tropical biodiversity“, said Schmitt. „The findings underline the need for protection efforts to preserve rare tree species in all tropical forest areas“. The initiative for the study came from Professor Ferry Slik of the University of Brunei Darussalam. The team published the research findings in the international journal PNAS.

The study corrects two hitherto common assumptions. The maximal possible number of tropical trees species was found to be around 53,000 - far higher than previous estimates. The Indo-Pacific forests, with around 19,000 to 25,000 species, did not have less tree species but was similarly species-rich as the Neotropics, i.e. continental Central and South America including the southern extratropical regions and the West Indies. The study finds that, in comparison, the tropical forests of continental Africa are relatively depauperate with some 4.500 to 6.000 tree species. The distribution area of most tropical tree species is limited to the three mentioned regions. The study also shows that most tree species are extremely rare, meaning that they may be under serious risk of extinction at current deforestation rates.

Original publication:
J. W. Ferry Slik et al.: An estimate of the number of tropical tree species. PNAS 2015.

More information:University Freiburg



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