Namibia climate-vegetation model predicts significant contraction for half of major vegetation units by 2080

A modelling study in Namibia predicts that half of the country’s major vegetation units could undergo significant contraction by 2080, while three savanna or thornbush types have high potential for southward expansion. The results are projections based on present-day vegetation records and climate-model scenarios, rather than observations of vegetation change already underway.

The study examined major vegetation units along Namibia’s north-to-south aridity gradient, where vegetation ranges from open woodland in the northeast to low open shrubland in the south and mean annual precipitation varies from 100 to 600 mm. Namibia is projected to experience a 2°C increase in annual mean temperature by the end of the 21st century, and the study assessed how shifting climatic conditions could influence vegetation-unit distributions.

Researchers classified 1,986 vegetation relevés using cluster analysis, a Multi-Response Permutation Procedure and indicator species analysis. They then used Random Forest to model the current distribution of the vegetation classes. Potential distributions in 2080 were simulated using two Representative Concentration Pathways, RCP4.5 and RCP8.5, and climate projections from the IPSL-CM5A–LR and HAdGEM2–ES Global Climate Models.

Under both scenarios, the model predicted high expansion potential toward southern Namibia for Eragrostis rigidior–Peltophorum africanum mesic thornbush savannas, Combretum africanum–Terminalia sericea broad-leafed savannas, and Senegalia mellifera–Dichrostachys cinerea degraded thornbush savannas. Under RCP8.5, the model favoured proliferation of Combretum collinum–Terminalia sericea broad-leafed savannas and Senegalia mellifera–Dichrostachys cinerea degraded thornbush savannas, potentially displacing other vegetation types.

The supplied evidence is limited to the study abstract, which does not quantify projected areas of expansion or contraction or describe uncertainty in the model estimates. It also supports a modelling prediction for Namibia’s major vegetation units, not a measured or observed long-term change.

Subject of Research: Climate-change modelling of major vegetation-unit distributions along Namibia’s aridity gradient

Article Title: Potential distribution of major plant units under climate change scenarios along an aridity gradient in Namibia

Article References: Naftal, L., De Cauwer, V., & Strohbach, B. J. (2024). Potential distribution of major plant units under climate change scenarios along an aridity gradient in Namibia. Vegetation Classification and Survey, 5, 127-151. https://doi.org/10.3897/vcs.99050

Image Credits: AI Generated

DOI: 10.3897/vcs.99050

Keywords: Namibia, climate change, vegetation modelling, Random Forest, RCP4.5, RCP8.5, savannas, thornbush, aridity gradient, species distribution, Potential, distribution