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Accueil du site → Doctorat → Afrique du Sud → 2019 → Conservation Strategies of the Red Listed Brackenridgea zanguebarica Oliv. in Vhembe District Municipality, Limpopo Province, South Africa

University of Venda (2019)

Conservation Strategies of the Red Listed Brackenridgea zanguebarica Oliv. in Vhembe District Municipality, Limpopo Province, South Africa

Tiawoun, Makuete Andre

Titre : Conservation Strategies of the Red Listed Brackenridgea zanguebarica Oliv. in Vhembe District Municipality, Limpopo Province, South Africa

Auteur : Tiawoun, Makuete Andre

Université de soutenance : University of Venda

Grade : Doctor of Philosophy in Botany 2019

Résumé partiel
Brackenridgea zanguebarica Oliv. (Ochnaceae) commonly known as “Yellow Peeling Plane”, is an important medicinal plant species, and one of the most threatened tree species that is endemic to Thengwe village in Vhembe District, South Africa. It is widely harvested for traditional purposes and difficult to propagate sexually and asexually. Nowadays, it has become threatened and this unique plant population is believed to be declining in the Brackenridgea Nature Reserve (BNR). According to the Red List of South African plants, B. zanguebarica is considered a critically endangered medicinal plant. All these facts combined with a lack of knowledge on the conservation of this species prompted this study on its conservation. To ascertain the effective conservation and proper management of this multipurpose tree, this study was conducted with the aim to improve its conservation strategy by investigating current threats to the existence of B. zangueberica, the chemical constituents from the different plant parts, the propagation methods of the species, and the factors delaying the germination of its seeds. In this study, an assessment of the current population threats was important as a first step in conservation ; this would update the status of the species in its natural habitat. The current status of Brackenridgea zanguebarica was conducted through an extensive field survey in the Brackenridgea Nature Reserve (BNR), where a belt transect method was deployed to record quantitative information, while the harvesting damage was estimated using a sliding scale from 0 to 5. The structure of the populations in terms of the stem diameter size classes showed a bell shape vi pattern. About 60% of individuals showed some signs of plant parts extraction as the stem bark was reported to be the main plant part harvested. The population structure, however, was dominated by juvenile plants due to the selective harvesting of mature individuals ; this hinders fruit production leading to poor or slow seed production. The present study aimed to compare the chemical constituents and the antimicrobial activities of some parts of this plant species. The extracts were screened for phytochemicals using standard methods. Thin-layer chromatography (TLC) was carried out to compare the chemical constituents using various solvent systems of varying polarity. Agar well diffusion and broth microdilution methods were used to evaluate the antimicrobial activity and the minimum inhibitory concentrations (MIC) of plant extracts respectively, against three bacteria and four fungi.

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