Background: Species checklists are a way in which local biodiversity can be monitored. There is no readily accessible database or checklist of diatom flora of South Africa. This publication gives an account of the diatom taxa encountered during two survey projects (2010–2012 and 2015–2017) within the Eastern Karoo. Objectives: This list has been compiled to allow for: (1) comparisons with future research in the geographical area; (2) comparison with ecological data from other countries; (3) monitoring the occurrence of new species; and (4) documentation of the disappearance of ‘clean water’ indicator species. Methods: Sampling took place in the area known as the Eastern Karoo during the two projects. Samples were scrubbed, cleaned and checked for live cells. Permanent slides were made and diatoms identified using light and electron microscopy. Each species was assigned a four-letter code from the software Omnidia version 6. Results: A total of 474 taxa were encountered, some of which are, as yet, undescribed. This list contains taxonomic rank currently assigned as well as the Omnidia codes as this software is commonly used throughout the world and in South Africa for diatom assessment protocols. Conclusion: The National Environmental Management: Biodiversity Act does not cover the protection of diatom species, which can only realistically be conserved if the habitats in which they are found are also conserved. This species checklist can serve as a catalyst for a move towards legislation accepting the use of diatoms as bioindicators for freshwater within South Africa.
Background and aim: The promotion of indigenous floral diversity would have a positive impact on ecosystem services and provide a source of additional income for local residents. Sesamum radiatum (Pedaliaceae) has great potential because it can provide a wide range of ornamental, ethnobotanical and nutritional services. Genetic studies are advocated before the increased introduction of a species into green spaces. Therefore, we aimed to study genetic diversity and differentiation among both disjunct and geographically close populations of S. radiatum in Gabon and Cameroon, to better manage indigenous genetic resources. Methods: Thirteen autochthonous populations of S. radiatum from two disjunct savanna areas of southeastern Gabon and northern Cameroon, separated by rain forest, were analysed using a highly reproducible high annealing temperature-random amplified polymorphic (HAT-RAPD) protocol. Genetic differentiation was assessed using distance-based and Bayesian approaches. Results and conclusion: The observed values of genetic differentiation between populations varied considerably (FST 0.041 to 0.706), with the majority found in the very high genetic differentiation range. Only two major genetic clusters were identified, mostly coinciding with geographic sampling areas. One of the populations from Cameroon showed signs of admixture possibly due to more intense agricultural activities in the area. The genetic differentiation among geographically close populations in Gabon is weak and most likely due to indigenous anthropogenic activities in connection with the traditional use of S. radiatum. Thus, the production and dissemination of planting material used, for instance, for green space development should take place within the main clusters in order not to distort the existing genetic structure, while benefiting from sufficient genetic diversity within the regions themselves. Keywords: green spaces, indigenous species, genetic diversity, Sesamum radiatum
Background: It is unclear how climate shifts may interfere with the diversification of tightly associated species interactions. Obligate pollination mutualisms are ideal for investigating the underlying processes of niche evolution by environmental change. Objectives: Niche evolution that corresponds with phenotype-by-environment interactions that include climate shifts is expected to affect the stability of partner associations of mutualisms. Here, we compare the evolution of fig syconium size and growth form strategies for coping with soil water stress during a range expansion by Ficus into arid environments. Methods: Niche models of 31 Ficus taxa were used to define contemporary habitat requirements of each species, which are then incorporated into Bayesian mixed models to examine the response of each trait to the soil water variables, other environmental variables and phylogenetic dependencies. Results: The results showed that phylogenetic constraints best explained syconium size variation, while environmental lability best characterised growth form variation. Two species adapted to arid environments that exhibited convergence in these traits had significantly different habitat requirements compared to forest and savanna species. Conclusion: The niche expansions by Ficus ilicina and Ficus cordata involved distinct historical processes. The findings suggest selection for traits that varied at different temporal scales limit the rate of niche expansions, and potentially destabilise mutualist partnerships and promote host shifts.
Background: In degraded environments such as oldfields, nurse plants can facilitate the growth of targeted restoration plant species through ameliorating them from extreme environmental conditions, creating nutrient rich microclimates, and protecting recruiting plants from grazing. Objectives: This study examined the role of Vachellia karroo nurse plant on soil physico-chemical properties and vegetation diversity in oldfields targeted for passive restoration at Tanglewood research farm in Eastern Cape Province, South Africa. Methods: Soil were quantified for physico-chemical properties in 48 plots measuring 25 m2 (5 m x 5 m) that were located under and outside 24 V. karroo nurse plants. In addition, detailed vegetation surveys were conducted in the above-mentioned plots. Results: Our results show that soil total N and C concentrations were higher under than outside V. karroo nurse plants. Soil penetration resistance and water repellency levels were lower under than outside V. karroo nurse plants, however monthly variations were also observed. Species richness and Shannon-Wiener diversity were higher under than outside V. karroo nurse plants, with species such as Searsia crenata, Azima tetracantha, Asparagus africanus, and Opuntia sp., frequently occurring under V. karroo nurse plants. Conclusion: The study concludes that V. karroo nurse plant has a positive effect on some soil physico-chemical properties and vegetation diversity underneath it. It is recommended that V. karro needs to be included in future oldfield restoration strategies if passive restoration at Tanglewood research farm is to be successful.
Background: The vegetation type boundaries in the North West province as they appear in the 2018 National Vegetation Map, for the most part, are derived from agricultural land types that were mapped in the 1980s. Aim & objectives: Given (1) the importance the National Vegetation Map plays in conservation assessment and planning, as well as environmental planning and decision making; and (2) the map boundary errors reported by users, an update of the provincial vegetation map was considered necessary. Methods: A vegetation identification key using high-level environmental parameters (in order of importance: flooding, bioregion, terrain, geology and soil) was developed. This key was used to manually interpret high-resolution colour aerial imagery, together with existing environmental spatial datasets (land types as a proxy for soils, simplified geology and terrain/land form). The existing vegetation type concepts are sound and are mostly retained in this map. Results & conclusion: Changes to the map include: (1) all vegetation boundaries in the province are remapped; (2) Olea Sclerophyllous Forest is proposed as a sub type/community related to the Northern Afrotemperate Forest vegetation type; (3) two existing vegetation types currently not mapped as occurring in the province are brought into the province, namely, Subtropical Alluvial Vegetation and Waterberg Mountain Bushveld; and (4) three vegetation units recognised in previous vegetation studies and which are not indicated in the current National Vegetation Map are included here as new vegetation types, namely, Vryburg Thornveld, Morokweng Thornveld and Central Sandy Mountain Bushveld. The descriptions of all terrestrial vegetation types occurring in the province are also updated and an updated annotated global plant species list for the province is provided. Changes reflected in this vegetation map have been incorporated into the National Vegetation Map Version 2024 beta.
