Vegetation map of South Africa, Lesotho and Swaziland 2018: A description of changes since 2006

Background: The Vegetation Map of South Africa, Lesotho and Swaziland (National Vegetation Map [NVM]) is a fundamental data set that is updated periodically. The National Biodiversity Assessment (NBA) 2018 process provided an opportunity for a more comprehensive revision of the NVM and better alignment between the terrestrial, marine and estuarine ecosystem maps. Objectives: The aim of this study was to update the NVM 2018 and quantify spatial and classification changes since NVM 2012, and describe the rationale and data sources utilised. We also quantified spatial errors corrected in this version, highlighted progress since NVM 2006, and identified errors and gaps to make recommendations for future revisions. Method: Edits made to the NVM in ArcMap 10.4 were categorised into the following five groups for analysis: (1) New types, (2) Boundary edits, (3) Realm re-assignment, (4) Removed and replaced vegetation types and (5) Deleted map area. Changes were quantified by category and biome. We used various software platforms to correct and quantify spatial errors since 2006. Results: Vegetation types were added (n = 47), removed (n = 35) and had boundary edits (n = 107) in NVM 2018, which affected over 5% of the total map area, compared to 2.6% (2012) and 0.5% (2009) for previous versions. Several sources of error were identified and fixed, and prompted the development of standard mapping protocols. Conclusion: National Vegetation Map 2018 is the most substantial revision of this data set that now fully aligns with maps of all other realms that form part of the NBA. However, parts of the map remain unrefined and provide opportunities for future work.