Site icon Conservation news

New assessment method finds close to one-third of tropical Africa’s plants are potentially facing extinction

  • A new study, published today in the journal Science Advances, uses a novel methodology based on key components of the IUCN Red List’s assessment process to discern the potential conservation status of tropical flora at the continental scale.
  • Researchers tested the new assessment method using the recently developed RAINBIO database, which consists of over 600,000 geo-referenced occurrence records of more than 20,000 vascular plant species in tropical Africa.
  • The research team found that 17.3 percent of the 22,036 vascular plant species included in the study are likely threatened, while 14.4 percent are potentially threatened. That means that nearly one-third — 31.7 percent — of tropical Africa’s vascular plant species might be at risk of going extinct.

New research finds that nearly one-third — 31.7 percent — of tropical Africa’s vascular plant species might be at risk of going extinct.

The International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species is the go-to resource for conservation status assessments, but while the majority of vertebrate species have been assessed, we know far less about the conservation status of plants, especially in the tropics. The IUCN Red List includes assessments of 86 percent of mammals and 61 percent of birds, but less than 8 percent of the estimated 352,000 vascular plant species worldwide.

The new study, published today in the journal Science Advances, uses a novel methodology based on key components of the IUCN Red List’s assessment process to discern the potential conservation status of tropical flora at the continental scale. Tariq Stévart, a researcher with the Missouri Botanical Garden in the United States and Université Libre de Bruxelles in Belgium led a team that developed what they call the “Preliminary Automated Conservation Assessment” (PACA) method for determining the conservation status of large numbers of species as an alternative to the much more time-consuming approach used for Red List assessments, which considers one species at a time.

Stévart and team tested their new assessment method using the recently developed RAINBIO database, which consists of over 600,000 geo-referenced occurrence records of more than 20,000 vascular plant species in tropical Africa. “Tropical Africa is a highly suitable model for undertaking such a study as it is faced with significant and mounting threats resulting from a wide range of activities, including logging, fuelwood collection, and deforestation for agriculture and mining,” Stévart and co-authors write in the study.

After applying their PACA approach to the RAINBIO database, the researchers were able to categorize each species into five preliminary conservation status levels: likely threatened, potentially threatened, likely rare, potentially rare, and likely not threatened.

Example of a critically endangered tree species from Tanzania. Credit: Thomas L.P. Couvreur (IRD).

The research team found that 17.3 percent of the 22,036 vascular plant species included in the study are likely threatened, while 14.4 percent are potentially threatened. Another 33.2 percent are likely rare, meaning that their distribution and habitat have declined, and while they could certainly become threatened with extinction in the future, they are not currently expected to decline any further.

In addition to determining which species are facing the most severe threats of extinction, the researchers also looked at the regions of Africa where vascular plants have fared the worst. They found that West Africa, the Ethiopian highlands, central Tanzania, and southern Democratic Republic of the Congo could lose 40 percent or more of their current plant diversity. Eight of the 10 countries that were found to have the highest number of threatened species are in West Africa.

The researchers say their PACA method has several advantages, saving time and money while carrying out assessments of numerous species at once. “This study is the first large-scale assessment of the potential conservation status of the tropical African flora, explicitly using the IUCN’s methodology,” tropical botanist Thomas Couvreur, a senior researcher at the French National Institute for Sustainable Development (IRD) who coordinated the study, said in a statement. “These assessments could provide crucial information for improving biodiversity management and promoting sustainable economic development in Africa.”

The preliminary assessments provided by the PACA method are not meant to replace the comprehensive assessments carried out by the IUCN that produce the official conservation status for species, Couvreur added. “The two approaches are complementary, and a significant international effort is still needed to assess all plant species in Africa,” he said.

Study co-author Bonaventure Sonké noted that “These results were possible because the partners involved agreed to share their data,” adding: “This is a strong signal to encourage researchers to share their data, in order to obtain results on a larger scale.”

The researchers write that “PACA can facilitate analyses of the level of conservation concern of a large number of species or of the entire flora of a given area and can help identify species that are likely to be threatened and therefore may require additional attention, including full Red List assessments.”

Example of an endangered orchid species from Cameroon and Gabon. Credit: Vincent Droissart (IRD).

CITATIONS

• Dauby, G., Zaiss, R., Blach-Overgaard, A., Catarino, L., Damen, T., Deblauwe, V., … & Engledow, H. (2016). RAINBIO: a mega-database of tropical African vascular plants distributions. PhytoKeys, (74), 1. doi:10.3897/phytokeys.74.9723

• Stévart, T., Dauby, G., Lowry II, P. P., Blach-Overgaard, A., Harris, D. J., Mackinder, B. A., Schatz, G. E., Sonké, B., Sosef, M. S. M., Svenning, J.-C., Wieringa, J. J., & Couvreur, T. L. P. (2019). A third of the tropical African flora is potentially threatened with extinction. Science Advances 5(11). doi:10.1126/sciadv.aax9444

FEEDBACK: Use this form to send a message to the author of this post. If you want to post a public comment, you can do that at the bottom of the page.