Factors influencing vegetation composition in grasslands under contrasting land use in Gauteng Province, South Africa

Abstract Plant species composition is crucial for ecosystem functioning because it influences both ecosystem stability and productivity. Plant species composition is affected by abiotic factors such as environmental moisture and soil properties, as well as biotic influences related to land use and management, which include herbivore grazing. The objective of this study was to compare vegetation structure and composition between protected and adjacent unprotected areas in Gauteng Province, South Africa. Vegetation surveys were conducted at Abe Bailey Nature Reserve (ANR), Roodeplaat Dam Nature Reserve (RNR), and Suikerbosrand Nature Reserve (SNR). Three sites within each nature reserve were paired with adjacent unprotected sites, where species composition and soil chemical properties were determined in Modified-Whittaker plots (MWPs). Plant species were recorded in 18 MWP plots of 1000m 2 area, and also species cover, density, and growth forms were recorded in 180 subplots of 1m 2 area. We determined similarity in species composition between paired sites using the Jaccard and Sørensen similarity indices, as well as the Bray-Curtis dissimilarity index. We further assessed variations in species composition between study locations and their relations with soil properties using Detrended Correspondence Analysis and Canonical Correspondence Analysis. There was low species composition similarity between the two land use types, but between locations, the ANR and SNR sites showed the most similarity in species composition. The soil variables differed significantly at some paired sites and also between locations. In general, the results indicated a strong association between species composition and environmental factors, specifically soil properties and herbivore grazing intensity.