Mapping plant communities of the Karoo National Park, South Africa, using Sentinel-2 and topo-morphological data

Abstract

• Vegetation classification improve our knowledge and understanding of complex ecosystems. • Vegetation classification, description and mapping method for large areas (> 90 000 hectares). • The use of Sentinel-2 and topo-morphological data in conjunction with limited floristic surveys (new approach) resulted in an accurate classification, description and vegetation map of the Karoo National Park. • A total of 12 major plant communities and two sub-communities that are distinctly linked to various abiotic factors were identified, described and mapped for the Karoo National Park. The higher-lying rocky steep midslopes as well as the valley bottomland areas had the highest diversity and species richness. This study aimed at classifying, mapping and describing the plant communities of the Karoo National Park using floristic surveys in conjunction with Sentinel-2 and topo-morphological data. Karoo National Park, Western Cape, South Africa. The vegetation of the Karoo National Park was delineated into homogenous physiognomic-physiographic units using Sentinel-2 images. A total of 128 survey plots (100 m 2 each) were surveyed within the different homogeneous units during the period 2016 to 2020. Within each survey plot, all rooted species were identified and their cover abundance estimated. Each plot was photographed and its geolocation recorded. The floristic data were captured using the Braun Blanquet Personal Computer suite and exported to the JUICE Software programme. A modified TWINSPAN classification was done to derive a first tabled synopsis of the plant communities. The different plant communities were subsequently classified and described according to their diagnostic and dominant species gleaned from the synoptic table. Species richness was determined by counting the number of different species per plant community while the Shannon–Wiener Index and Rich-Gini–Simpson Index of diversity (D) were used to derive indices of species diversity per plant community. 12 major communities and two sub-communities that are distinctly linked to various abiotic factors were identified, described and mapped. The higher-lying rocky steep midslopes as well as the valley bottomland areas had the highest diversity and species richness. This study proves the efficacy of using Sentinel-2 and topo-morphological data in classification, description and mapping vegetation of extensive natural areas. The vegetation map and classification of plant communities provide a baseline to inform management decisions. Taxonomic reference: SA-Plant Checklist-2019–2020, South African National Biodiversity Institute, 2020, Botanical Database of Southern Africa (BODATSA) ( http://posa.sanbi.org/ ) [accessed January 2022].