A living inventory of planted trees in South Africa compiled using iNaturalist
Although South Africa has an amazingly diverse flora, with around 24,000 native plant species, the country was not blessed with many native TREE species suitable for cultivation to produce timber and other ecosystem services. Consequently, the country has a long history of tree introductions from other parts of the world, starting in the mid-17th century.
Planted trees (both native and non-native) now dominate “treescapes” (landscapes with many trees) in many parts of the country, especially in urban ecosystems. Planted trees are a key component of South Africa’s “green infrastructure” and they provide diverse ecosystem services.
Perceptions of the role of trees in our landscapes have changed over time and continue to change. While trees provide many valuable services, they also have negative impacts in some areas and some contexts (https://tinyurl.com/mr3sh46x). Many initiatives to mitigate the impacts of climate change involve manipulating the cover and diversity of trees.
Effective management of our tree cover requires us to know which species are planted where. However, no up-to-date list of planted tree species exists for South Africa.
South Africans have embraced iNaturalist since it was launched in 2008. Since then more than 38,000 observers have submitted around 4.5 millions records of some 42,000 native and non-native species. Although iNaturalist focuses largely on species “in the wild” (i.e. not in captivity or cultivated), many records are posted of trees growing in plantations, rural landscapes and urban ecosystems.
A project was launched in 2022 to use iNaturalist data to compile a “living inventory” of planted tree species in South Africa. This involved careful checking of species identifications and verification of the “planted” status of records.
Details of the “living inventory” produced from this project appear in a paper published in the South African Journal of Botany in August 2024 (https://tinyurl.com/yvu2unzp). The database compiled in this project comprised over 35000 records of 805 “taxa” (>90% of records could be confidently identified to species level, but some only to the level of genera or other higher-order groups), 79% of which are non-native. Over a third these taxa belong to three families: Fabaceae (pea or legume family), Myrtaceae (myrtle family, including eucalypts) and Arecaceae (palms).
The inventory will improve in value over time as the number of records grows and the geographic coverage of sampling increases. It already has many potential uses, including:
• guiding management of tree pests and diseases (it has already been applied for this purpose for the polyphagous shot hole borer; https://tinyurl.com/yc82zj4e);
• urban greening initiatives;
• monitoring for new invasions; and
• planning nature-based solutions.
Please join the iNaturalist project at: https://www.inaturalist.org/projects/tree-planting-in-south-africa and contribute records!
