Browsing by Subject "Local knowledge"

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    Distribution quantitative morphological variation and preliminary molecular analysis of different growth forms of wild rooibos (Aspalathus linearis) in the northern Cederberg and on the Bokkeveld Plateau
    (2010) Malgas, R R; Potts, A J; Oettlé, N M; Todd, Simon Wallace; Verboom, George Anthony; Hoffman, M T
    Aspalathus linearis (Fabaceae) is endemic to the Cape Floristic Region in the Western Cape and Northern Cape Provinces of South Africa. The reddish leaves and stems, primarily of one cultivar, are used to make a commercially important tea which is marketed locally and internationally as ‘rooibos’ or ‘redbush’ tea. In historical times rooibos was collected in the wild. In the twentieth century cultivation of a single cultivar increasingly replaced wild harvest to meet growing demand. Recently, tea from wild forms of the species, which vary significantly in growth form and reproductive strategy, has been marketed by small-scale farmers in Wupperthal and on the Suid Bokkeveld plateau in the northern part of the species' distribution. Little information on the wild forms of this species has been published, although a rich body of knowledge exists amongst local harvesters and other land-users. In this study, we focus on the northern part of the species’ distribution area where wild rooibos is harvested for commercial sale to niche organic and fair-trade markets. We adopt a transdisciplinary approach to (1) document the different growth forms, (2) develop a bioclimatic model of the potential distribution of the species, (3) quantify the morphological variation that exists between growth forms relative to the established cultivar and (4) use molecular techniques to provide a preliminary insight into the infraspecific diversity of different wild A. linearis growth forms. Our results show that local land users in the region identify four main growth forms of wild A. linearis. These are an ‘erect form’ and a ‘prostrate form’ in the Wuppertal area, a ‘shrub form’ in the Suid Bokkeveld, and a ‘tree form’ that has been observed at specific sites at Wupperthal, Biedouw and the Suid Bokkeveld. The PCA analysis of seven morphological traits identified three growth forms, which support the land user descriptions except in the case of the 'tree' and 'erect' forms which co-occurred in coordinate space. Both shrub and prostrate forms are wider than they are taller and possess more stems closer to the ground than erect forms. While the stems of both shrub and prostrate forms lie relatively flat on the ground, stem thickness is significantly greater in shrub forms. The tree type, the erect form and the cultivar studied possess the highest harvestable biomass. Prostrate forms and shrub forms resprout after fire while erect and tree forms regenerate from seed only. Haplotypic variation was assessed using DNA sequences from a single chloroplast region and revealed strong genetic differences between the different growth forms. Although preliminary, there is some evidence that sprouting and nonsprouting forms of the species are genetically isolated. This has important taxonomic implications for the species. Additional chloroplast regions and a nuclear region were also identified as variable and potentially useful markers for a multi-locus molecular approach to studying taxonomic and ecological questions within the species.
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    Ecotypes of wild rooibos ( (Burm. F) Dahlg. Fabaceae) are ecologically distinct
    (Elsevier, 2011) Hawkins, H-J; Malgas, R; Bienabe, E
    Aspalathus linearis (Burm. F) Dahlg., Fabaceae is cultivated by small- and large-scale commercial farmers of the Cederberg and Bokkeveld Plateau in the Cape Floristic Region of South Africa, for the production of an herbal beverage called 'rooibos' or 'rooibos tea'. Small-scale farmers also harvest A. linearis from the wild and market the tea as an organic and fair-trade certified product. However, little is known about the apparent ecotypes of wild A. linearis. We hypothesized that 1) rooibos ecotypes are ecologically distinct (occurring in different plant communities defined by environmental variables); 2) rooibos ecotypes are functionally distinct due to variance in water use efficiency; and 3) rooibos ecotypes are associated with threatened vegetation types/species, making populations of wild rooibos ecotypes worthy of conservation. Ecotypes of wild rooibos were identified based on plant habit and local knowledge. Plant communities were classified using Twinspan, environmental factors were tested as predictors of ecotype distribution and water use efficiency of ecotypes growing across a rainfall gradient was determined from foliar natural abundance of 13C. Wild rooibos was not generally associated with endangered vegetation types but was associated with plant species having endangered status. Wild rooibos occurred in four plant communities and comprised five wild rooibos ecotypes: shrub, tree, upright, salignus and prostrate types. Although some ecotypes clearly co-occurred, evidence is provided for habitat preference between the ecotypes: Prostrate and upright ecotypes occurred at higher elevations (>400–600 m). Shrub ecotypes occurred at lower rainfall sites (<200 mm p.a.) and the salignus ecotype occurred at higher rainfall sites (>500 mm p.a.). Foliar 13C indicated greater water use efficiencies by ecotypes in relatively drier areas. The extent to which this is a plastic or inherent response requires further investigation. Considering that wild rooibos ecotypes differ both ecologically and possibly also functionally and genetically, it is concluded that populations of wild rooibos ecotypes should be considered as distinct and worthy of conservation. This distinctness should be considered when farmers apply for both harvesting and ploughing rights on land with wild rooibos ecotypes.