Challenges in mapping land degradation in South Africa
New research co-authored by SEEC’s Stephni van der Merwe, Vernon Visser, Wataru Tokura and Andrew Skowno underscores the challenges of accurately mapping land degradation in South Africa, a critical task for reporting to the United Nations Convention to Combat Desertification (UNCCD).
The recently published study, led by Colleen Seymour from the South African National Biodiversity Institute, compared five UNCCD-recommended models for assessing land productivity trends between 2016 and 2019 using the Trends.Earth tool. The findings revealed striking differences: the most pessimistic model estimated that 35% of South Africa’s land was degraded, while the most optimistic suggested only 15% degraded and more than 70% improved.
Differences also emerged in where degradation was mapped. Models that accounted for rainfall tended to classify land more favourably, especially in shrubland biomes, while grasslands were consistently less likely to be marked as degraded. With 59–78% of the country experiencing drought during the reporting period, rainfall patterns had a major influence on outputs.
“Land degradation threatens biodiversity and people’s livelihoods. In a climatically diverse country like South Africa, estimates from remote sensing can vary dramatically depending on how rainfall is accounted for. The study shows the importance of involving ecologists with knowledge of local landscapes, supported by field data, to select the most appropriate models for national reporting,” explains Stephni van der Merwe
The researchers emphasise that mapping and monitoring land degradation is vital for biodiversity conservation and sustainable livelihoods, but must be underpinned by careful interpretation and validation to ensure reliable national assessments.