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Polygala sekhukhuniensis Retief, Siebert & A.E.Van Wyk (Polygala; section Polygala; subsection Heterolophus), a new species with a restricted range in Sekhukhuneland, South Africa, is described, illustrated and compared with other members of the genus. It is a dwarf shrub that can be distinguished by its much-branched habit, sparsely flowered inflo...
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... m; P / E = 1.02 ( Table 2). Apertures 22, zonocolporate. Ectoapertures (17) 18.6 (21) × (1) 1.2 (3) m; endoapertures (1) – 4.8 – (6) μ m × endocingulate. Surface ornamentation psilate to finely granular, with scattered lumina in apocolpial areas that are small (less than 1 μ m). Opercula present. Pollen grains of P. sekhukhuniensis , and P. hottentotta differ from P. leptophylla var. leptophylla and P. seminuda in shape, namely oblate versus prolate and prolate-spheroidal respectively (Fig. 3). Opercula over the endoapertures of P. sekhukhuniensis , P. hottentotta and P. seminuda are pronounced, mostly so in the new species (Fig. 4). Although the shape of pollen grains of P. sekhukhuniensis and P. hottentotta are very similar, the former has smaller grains (Table 2). Polygala sekhukhuniensis is only known from Sekhukhuneland (Fig. 4). P. sekhukhuniensis and P. hottentotta occur on patches of anomalous soils in this region — sparsely vegetated soils that are mineralized and rich in heavy metals (Table 3). These soils are clayey and highly erodible, in contrast to the rocky, sandy soil on mountain slopes that is preferred by P. leptophylla var. leptophylla . These anomalies are akin to erosion gulleys, but in this case not due to human disturbance, but caused by natural erosion processes due to a weak soil structure and associated high water dispersability (Mason, 1959). According to Siebert et al. (2002) and Mandiwana et al. (2007), plant communities typical of these eroded sites in Sekhukhuneland include heavy metal accumulating or excluding species (Table 4). Polygala sekhukhuniensis is such a species, specifically adapted to grow in erosion gulleys of exposed heavy metal contaminated (ultramafic) soil. Hence, the opinion that the ecological species concept is an essential part of the biological species concept (Grant, 1992) is supported here. Asymmetry and within-plant variance are higher between specimens of the same species in the contact zone between ultramafic and normal soils (Alados et al., 1999). This variance provides genetic material for natural selection and subsequent reproductive isolation. In the case of P. sekhukhuniensis , an open niche with an anomalous Ca-rich substrate (14.68% = 146 800 ppm) in an otherwise typical environment of soils rich in Mg (8.48% = 84 800 ppm) and poor in Ca (2.13% = 21 300 ppm) (Fig. 5A), probably favoured speciation. Similar to limestone, the soils inhabited by P. sekhukhuniensis have a high Ca:Mg ratio (2:1), which differ significantly from the soil substrate of P. hottentotta (1Ca:4 Mg) in the study area (Fig. 5A). As a consequence P. sekhukhuniensis has a leaf Ca:Mg ratio of 16:1, and P. hottentotta a ratio of 4:1 (Fig. 6A). O'Dell et al. (2006) have shown that the ability to maintain high leaf Ca:Mg is a key evolutionary change needed for survival on heavy metal soil and represents the physiological feature distinguishing the plant species adapted to heavy metal soils from their non-adapted congeners. Furthermore, soils in which the two Polygala taxa grow have high concentrations of total Cr, Al and Fe (Fig. 5A,B), with Polygala hottentotta holding higher concentrations of Al and Fe in its roots, stems and leaves, but not at levels that could be considered as accumulating (Fig. 6B). P. sekhukhuniensis excludes these metals more effectively, despite the associated soil concentrations being higher (Fig. 5B). Overall it seems that P. sekhukhuniensis is the better excluder of heavy metals due to higher leaf Ca concentrations as a previously confirmed pro- tection and survival mechanism (Konstantinou and Babalonas, 1996). It is suggested that P. sekhukhuniensis originated as an ecotype of and has developed from its suggested closest relative, P. leptophylla , which occurs on nearby mountain slopes. This theory was already proposed for Sekhukhuneland endemics by Knowles and Witkowski (2000), suggesting that the genetic properties of individuals occurring on iron-rich mountain slopes have the potential to immigrate to, adapt to and colonize ultramafic soils rich in heavy metals. It is hypothesized that P. sekhukhuniensis is a typical edaphic specialist which may well have speciated recently, after the Pleistocene (Reeves et al., 1983). It probably prefers the competition-free, open niches of eroded, toxic ultramafic soils where it has a physiological advantage requiring high levels of Ca to tolerate heavy metals (Fig. 6A). P. sekhukhuniensis , like Euclea sekhukhuniensis , can therefore be considered a heavy metal excluding, calciotrophic species. Polygala sekhukhuniensis has a small geographical range in Sekhukhune Plains Bushveld (Siebert et al., 2002), and limited area of occupancy within natural erosion gulleys (dongas). Most of its habitat is under threat from slimes dams and rock dumps associated with the mining industry, as these eroded areas are considered to be of low conservation status. P. sekhukhuniensis is not formally protected in any conservation area. Populations of the species should therefore be closely monitored and its Red Data List assessment assessed. The conservation value of P. sekhukhuniensis is considered relatively high, as it could possibly be used as a keystone species in the ecology of mine dumps due to its internal mechanism of excluding heavy metals. The specific epithet refers to the geographical area the species occurs in, namely Sekhukhuneland, a region named for King Sekhukhune(-i) I (1814 1882) of the Bapedi tribe. For consistency, and in line with existing Latin epithets of plants named after the region, it is based on the alternative spelling, “ Sekhukhuniland ” . We would like to propose the names “ sekhukhune milkwort ” and “ sekhukhunebloukappie ” as Eng- lish and Afrikaans vernacular names, respectively. The recorded Northern-Sotho names for the plant are mabo š êkgo and mogaletsaoi , which differs from the vernacular name, pe- loterri , given to the closely related P. leptophylla var. leptophylla . Burnt ashes are mixed with snuff for flavouring ( Barnard 209 ) and the roots are cooked and given to forgetful people to make the mind sensible ( Barnard 135 ). LIMPOPO. 2429 (Zebediela): Mankopanie, Farm Hoera- roep ( – BD), Barnard 209 (PRE); Bewaarkloof, Potlake Nature Reserve ( – BD), Van Rooyen 2339 (PRE); Potlake Nature Reserve ( – BD), Matthée 1044 (PRU); Farm Geeneinde, Sekukuniland ( – DB), Barnard & Mogg 737 (PRE); Sekhukhuniland, Farm Parys ( – DB), Barnard & Mogg 738 (PRE). MPUMALANGA. — 2430 (Pilgrim's Rest): Maandagshoek ( – CA), Kritzinger 118 (PRE, PRU); Steelpoort, Eastern Chrome Mines, valley beneath mountain in the Winterveld mine area ( CA), Siebert 449 (PRU); Sekukuni ( CC), Barnard 135 (PRE); Dwarsrivier, 5 km on turn-off to Lydenburg from Stofberg-Steelpoort road ( – CC), Jordaan 782 (PRE); 2 km from Spitskop turn-off south on Steelpoort-Lydenburg road ( – CC), Burgoyne 6015 (PRE); Thornecliffe Chrome Mine, hill west of office ( – CC), Van Wyk & Siebert 12982 (PRU); Steelpoort, Ferrochrome Holdings, 4 km to east of Spitskop on way to Roossenekal ( – CC), Siebert 337 (PRU); Turnoff to Thornecliffe Mine from Lydenburg, Steelpoort road ( – CC), Van Wyk & Siebert 13311 (PRU); Road between Steelpoort and Kennedy's Vale ( – CC), Siebert & Van Wyk 1379 (PRU). The authors are indebted to Maggi Loubser, Geology Department, University of Pretoria, for assistance with XRF analyses and to Nina van Vliet, Department of Soil, Climate and Water, Pretoria, for assistance with AAS and ICP-MS analyses. We would like to thank Hugh Glen, for translating the diagnoses into Latin, Kevin Balkwill for constructive comments on a draft of the manuscript, Hester Steyn, for preparing the distribution map and Daleen Roodt for the line drawings. The National Research Foundation, University of Pretoria and South African National Biodiversity Institute provided financial ...
Context 2
... m; P / E = 1.02 ( Table 2). Apertures 22, zonocolporate. Ectoapertures (17) 18.6 (21) × (1) 1.2 (3) m; endoapertures (1) – 4.8 – (6) μ m × endocingulate. Surface ornamentation psilate to finely granular, with scattered lumina in apocolpial areas that are small (less than 1 μ m). Opercula present. Pollen grains of P. sekhukhuniensis , and P. hottentotta differ from P. leptophylla var. leptophylla and P. seminuda in shape, namely oblate versus prolate and prolate-spheroidal respectively (Fig. 3). Opercula over the endoapertures of P. sekhukhuniensis , P. hottentotta and P. seminuda are pronounced, mostly so in the new species (Fig. 4). Although the shape of pollen grains of P. sekhukhuniensis and P. hottentotta are very similar, the former has smaller grains (Table 2). Polygala sekhukhuniensis is only known from Sekhukhuneland (Fig. 4). P. sekhukhuniensis and P. hottentotta occur on patches of anomalous soils in this region — sparsely vegetated soils that are mineralized and rich in heavy metals (Table 3). These soils are clayey and highly erodible, in contrast to the rocky, sandy soil on mountain slopes that is preferred by P. leptophylla var. leptophylla . These anomalies are akin to erosion gulleys, but in this case not due to human disturbance, but caused by natural erosion processes due to a weak soil structure and associated high water dispersability (Mason, 1959). According to Siebert et al. (2002) and Mandiwana et al. (2007), plant communities typical of these eroded sites in Sekhukhuneland include heavy metal accumulating or excluding species (Table 4). Polygala sekhukhuniensis is such a species, specifically adapted to grow in erosion gulleys of exposed heavy metal contaminated (ultramafic) soil. Hence, the opinion that the ecological species concept is an essential part of the biological species concept (Grant, 1992) is supported here. Asymmetry and within-plant variance are higher between specimens of the same species in the contact zone between ultramafic and normal soils (Alados et al., 1999). This variance provides genetic material for natural selection and subsequent reproductive isolation. In the case of P. sekhukhuniensis , an open niche with an anomalous Ca-rich substrate (14.68% = 146 800 ppm) in an otherwise typical environment of soils rich in Mg (8.48% = 84 800 ppm) and poor in Ca (2.13% = 21 300 ppm) (Fig. 5A), probably favoured speciation. Similar to limestone, the soils inhabited by P. sekhukhuniensis have a high Ca:Mg ratio (2:1), which differ significantly from the soil substrate of P. hottentotta (1Ca:4 Mg) in the study area (Fig. 5A). As a consequence P. sekhukhuniensis has a leaf Ca:Mg ratio of 16:1, and P. hottentotta a ratio of 4:1 (Fig. 6A). O'Dell et al. (2006) have shown that the ability to maintain high leaf Ca:Mg is a key evolutionary change needed for survival on heavy metal soil and represents the physiological feature distinguishing the plant species adapted to heavy metal soils from their non-adapted congeners. Furthermore, soils in which the two Polygala taxa grow have high concentrations of total Cr, Al and Fe (Fig. 5A,B), with Polygala hottentotta holding higher concentrations of Al and Fe in its roots, stems and leaves, but not at levels that could be considered as accumulating (Fig. 6B). P. sekhukhuniensis excludes these metals more effectively, despite the associated soil concentrations being higher (Fig. 5B). Overall it seems that P. sekhukhuniensis is the better excluder of heavy metals due to higher leaf Ca concentrations as a previously confirmed pro- tection and survival mechanism (Konstantinou and Babalonas, 1996). It is suggested that P. sekhukhuniensis originated as an ecotype of and has developed from its suggested closest relative, P. leptophylla , which occurs on nearby mountain slopes. This theory was already proposed for Sekhukhuneland endemics by Knowles and Witkowski (2000), suggesting that the genetic properties of individuals occurring on iron-rich mountain slopes have the potential to immigrate to, adapt to and colonize ultramafic soils rich in heavy metals. It is hypothesized that P. sekhukhuniensis is a typical edaphic specialist which may well have speciated recently, after the Pleistocene (Reeves et al., 1983). It probably prefers the competition-free, open niches of eroded, toxic ultramafic soils where it has a physiological advantage requiring high levels of Ca to tolerate heavy metals (Fig. 6A). P. sekhukhuniensis , like Euclea sekhukhuniensis , can therefore be considered a heavy metal excluding, calciotrophic species. Polygala sekhukhuniensis has a small geographical range in Sekhukhune Plains Bushveld (Siebert et al., 2002), and limited area of occupancy within natural erosion gulleys (dongas). Most of its habitat is under threat from slimes dams and rock dumps associated with the mining industry, as these eroded areas are considered to be of low conservation status. P. sekhukhuniensis is not formally protected in any conservation area. Populations of the species should therefore be closely monitored and its Red Data List assessment assessed. The conservation value of P. sekhukhuniensis is considered relatively high, as it could possibly be used as a keystone species in the ecology of mine dumps due to its internal mechanism of excluding heavy metals. The specific epithet refers to the geographical area the species occurs in, namely Sekhukhuneland, a region named for King Sekhukhune(-i) I (1814 1882) of the Bapedi tribe. For consistency, and in line with existing Latin epithets of plants named after the region, it is based on the alternative spelling, “ Sekhukhuniland ” . We would like to propose the names “ sekhukhune milkwort ” and “ sekhukhunebloukappie ” as Eng- lish and Afrikaans vernacular names, respectively. The recorded Northern-Sotho names for the plant are mabo š êkgo and mogaletsaoi , which differs from the vernacular name, pe- loterri , given to the closely related P. leptophylla var. leptophylla . Burnt ashes are mixed with snuff for flavouring ( Barnard 209 ) and the roots are cooked and given to forgetful people to make the mind sensible ( Barnard 135 ). LIMPOPO. 2429 (Zebediela): Mankopanie, Farm Hoera- roep ( – BD), Barnard 209 (PRE); Bewaarkloof, Potlake Nature Reserve ( – BD), Van Rooyen 2339 (PRE); Potlake Nature Reserve ( – BD), Matthée 1044 (PRU); Farm Geeneinde, Sekukuniland ( – DB), Barnard & Mogg 737 (PRE); Sekhukhuniland, Farm Parys ( – DB), Barnard & Mogg 738 (PRE). MPUMALANGA. — 2430 (Pilgrim's Rest): Maandagshoek ( – CA), Kritzinger 118 (PRE, PRU); Steelpoort, Eastern Chrome Mines, valley beneath mountain in the Winterveld mine area ( CA), Siebert 449 (PRU); Sekukuni ( CC), Barnard 135 (PRE); Dwarsrivier, 5 km on turn-off to Lydenburg from Stofberg-Steelpoort road ( – CC), Jordaan 782 (PRE); 2 km from Spitskop turn-off south on Steelpoort-Lydenburg road ( – CC), Burgoyne 6015 (PRE); Thornecliffe Chrome Mine, hill west of office ( – CC), Van Wyk & Siebert 12982 (PRU); Steelpoort, Ferrochrome Holdings, 4 km to east of Spitskop on way to Roossenekal ( – CC), Siebert 337 (PRU); Turnoff to Thornecliffe Mine from Lydenburg, Steelpoort road ( – CC), Van Wyk & Siebert 13311 (PRU); Road between Steelpoort and Kennedy's Vale ( – CC), Siebert & Van Wyk 1379 (PRU). The authors are indebted to Maggi Loubser, Geology Department, University of Pretoria, for assistance with XRF analyses and to Nina van Vliet, Department of Soil, Climate and Water, Pretoria, for assistance with AAS and ICP-MS analyses. We would like to thank Hugh Glen, for translating the diagnoses into Latin, Kevin Balkwill for constructive comments on a draft of the manuscript, Hester Steyn, for preparing the distribution map and Daleen Roodt for the line drawings. The National Research Foundation, University of Pretoria and South African National Biodiversity Institute provided financial ...
Citations
... Regional geoecological studies have led to the discovery and description of rare and endemic edaphic specialists from Sekhukhuneland in Limpopo (Siebert et al. 2010). A phylogenetic study was also undertaken of the southern African Andropogoneae (Poaceae) to determine the potential of gene flow from Saccharum hybrids to wild relatives (Snyman et al. 2018 Taxonomists at NWU have made a concerted effort to contribute to national (Siebert et al. 2010) and regional (Struwig et al. 2015) ...
... Regional geoecological studies have led to the discovery and description of rare and endemic edaphic specialists from Sekhukhuneland in Limpopo (Siebert et al. 2010). A phylogenetic study was also undertaken of the southern African Andropogoneae (Poaceae) to determine the potential of gene flow from Saccharum hybrids to wild relatives (Snyman et al. 2018 Taxonomists at NWU have made a concerted effort to contribute to national (Siebert et al. 2010) and regional (Struwig et al. 2015) ...
AN INTRODUCTORY ADDRESS
... He also developed the first database of the collection which is now hosted on the BRAHMS platform. Regional geoecological studies have led to the discovery and description of rare and endemic edaphic specialists from Sekhukhuneland in Limpopo (Siebert et al. 2010). A phylogenetic study was also undertaken of the southern African Andropogoneae (Poaceae) to determine the potential of gene flow from Saccharum hybrids to wild relatives (Snyman et al. 2018 Taxonomists at NWU have made a concerted effort to contribute to national (Siebert et al. 2010) and regional (Struwig et al. 2015) efforts to categorize and name plants. ...
... Regional geoecological studies have led to the discovery and description of rare and endemic edaphic specialists from Sekhukhuneland in Limpopo (Siebert et al. 2010). A phylogenetic study was also undertaken of the southern African Andropogoneae (Poaceae) to determine the potential of gene flow from Saccharum hybrids to wild relatives (Snyman et al. 2018 Taxonomists at NWU have made a concerted effort to contribute to national (Siebert et al. 2010) and regional (Struwig et al. 2015) efforts to categorize and name plants. Subsequently, in recent years, closer collaboration has been sought and established with the Pretoria National Herbarium of the South African National Biodiversity Institute (PRE) through the appointment of two of their taxonomic experts as extraordinary lectures to improve the functioning of the herbarium, provide database support and stimulate collaborative fieldwork. ...
The A.P. Goossens Herbarium (PUC) was founded by Antonie Goossens in 1932 and today it holds over 30 000 specimens from central South Africa. A brief history of herbarium establishment, development as well as its educational purposes, results of scientific studies (taxonomical, ecological and biogeographical) and current status and problems are described and discussed.
... The newly collected specimens were deposited in Guilan (GUH) (Holotype) and Yasouj (Isotype) Universities Herbaria. The new species was identified using different Floras and related articles (Boissier 1867: 76, Shishkin 1964: 118, Cullen 1965: 533, Chrtek & Krisa 1977, Peşmen 1980, Davis et al. 1988, Jalilian 2005, Eren et al. 2008, Raabe et al. 2009, Siebert et al. 2010 Wahlert et al. 2017, Dönmez & Uðurlu Aydin 2018, Sarvi et al. 2020. It was also compared with other species of Polygala in central herbarium of Tehran University (TUH), herbarium of Shiraz University (HSHU), Iranian research institute of plant protection (IRAN), herbarium of research institute of forests and rangelands (TARI) and herbarium of animal & natural resources research center of Hormozgan province. ...
A new species, Polygala guilanica (Polygalaceae), is described from Kooh-Roubar, Gasht-Roodkhan protected area in W Guilan province, N Iran. The new species is distinguished based on its prostrate stem; small, lanceolate, ovate and rhombic, sessile leaves; tiny pink-white flowers in lax terminal racemes; 6 or 8 stamens with sessile anthers, a filiform style and brownish seed with 3-lobed caruncle. Detailed morphological description of the new species, photographs and distribution map are provided. Polygala guilanica is compared with the morphologically closest species: P. kurdica, P. hohenackeriana and P. anatolica. An updated identification key is provided for the Iranian species.
... The newly collected specimens were deposited in Guilan (GUH) (Holotype) and Yasouj (Isotype) Universities Herbaria. The new species was identified using different Floras and related articles (Boissier 1867: 76, Shishkin 1964: 118, Cullen 1965: 533, Chrtek & Krisa 1977, Peşmen 1980, Davis et al. 1988, Jalilian 2005, Eren et al. 2008, Raabe et al. 2009, Siebert et al. 2010 Wahlert et al. 2017, Dönmez & Uðurlu Aydin 2018, Sarvi et al. 2020. It was also compared with other species of Polygala in central herbarium of Tehran University (TUH), herbarium of Shiraz University (HSHU), Iranian research institute of plant protection (IRAN), herbarium of research institute of forests and rangelands (TARI) and herbarium of animal & natural resources research center of Hormozgan province. ...
A new species, Polygala guilanica (Polygalaceae), is described from Kooh-Roubar, Gasht-Roodkhan protected area in W Guilan province, N Iran. The new species is distinguished based on its prostrate stem; small, lanceolate, ovate and rhombic, sessile leaves; tiny pink-white flowers in lax terminal racemes; 6 or 8 stamens with sessile anthers, a filiform style and brownish seed with 3-lobed caruncle. Detailed morphological description of the new species, photographs and distribution map are provided. Polygala guilanica is compared with the morphologically closest species: P. kurdica, P. hohenackeriana and P. anatolica. An updated identification key is provided for the Iranian species.
... Consequently, through the process of speciation and natural selection, carbonate soils harbour unique plant communities with variable levels of endemism (Kruckeberg, 1969;Kruckeberg & Rabinowitz, 1985;Kruckeberg, 1986;Willis et al., 1996a;Cowling & Hilton-Taylor, 1997;Zhu et al., 2003;Qin et al., 2012;Smyčka et al., 2017). Endemic plant species on unusual soils are generally referred to as edaphic endemics, edaphic specialists or habitat specialists (Cowling & Holmes, 1992;Van Wyk et al., 2010;Magee et al., 2011;Goldblatt & Manning, 2012). Plants that are adapted to occupy Ca-rich habitats are referred to as calcicoles, calcicolous plants, calciphiles or calcicolous flora (Tansley, 1917;De Silva, 1934;Reinhardt et al., 2013;Rogers et al., 2018). ...
... Plant communities growing on carbonate soils are characterised by distinct species assemblages, high species richness and contribute significantly to regional as well as global plant diversity (Kruckeberg, 1969;Cowling, 1990;Zhu et al., 1998;Pärtel, 2002 Zietsman & Bredenkamp, 2007) and habitat loss (Willis et al., 1996a;Van Buren & Harper, 2003;Lu et al., 2016). Conservation of calcicolous floras remains challenging in Africa, due to restricted geographical plant distribution ranges and specific habitat preferences (Loehle, 2006;Retief et al., 2008;Van Wyk et al., 2010;Goldblatt & Manning, 2013). Thus, the second objective was to identify knowledge gaps and provide new perspectives by asking 86 significant questions that may contribute to future botanical research or guide conservation and management efforts of calcicolous plant communities in Africa. ...
... These included the provision of food and liquor to humans (Van Wyk et al., 2010), forage provision to livestock and game (Abd El-Ghani & Marei, 2007;Gamoun et al., 2010;Radloff et al., 2010;Gamoun, 2013;Ratovonamana et al., 2013) and the potential to assist with mine dump rehabilitation, especially those species that had the ability to exclude heavy metals (Retief et al., 2008). Some endemic species were found to have a medicinal value (Abd El-Ghani & Marei, 2007;Van Wyk et al., 2010). ...
The Griqualand West Centre (GWC) of plant endemism harbours a unique flora of which 24 species are endemic. Heterogeneous geology, climate and topography are considered drivers of the unique flora and local endemism. However, these drivers have not yet been investigated and our understanding of the effects thereof on vegetation dynamics remains poor. Four mountain ecosystems, each underlain by different rock types and with distinct climatic patterns, provided a setting to investigate the effects of ecological drivers shaping vegetation dynamics of this semi-arid area. Therefore, the primary aim of this study was to disentangle the effects of rainfall and geology, through soil properties related to the underlying geological parent material, as drivers of floristic patterns, plant diversity and structure, biomass production, and the relationship between diversity and biomass production. The objectives of this study were to (i) redefine the borders of GWC to establish which mountain ranges fall within the centre by using a MaxEnt spatial model based on geology, climate and topography in combination with distribution data of GWC endemics, (ii) describe the flora within the newly redefined borders of GWC based on dominant plant families and -species, indicator plant species, endemic species and species composition, (iii) compare soil properties, rainfall, plant diversity and structure between mountain ecosystems to test whether mountains, within the newly defined borders of GWC, differ significantly from each other, (iv) determine whether soil properties, rainfall or a combination thereof act as drivers of plant diversity and structural differences between mountains, (v) test for differences in total biomass production (above ground green plant material and debris), live biomass production (only live green above ground plant material) and respective plant functional group (PFG) biomass production between the four mountain rangelands, (vi) relate differences to specific soil properties and rainfall to identify the strongest drivers of biomass production, (vii) investigate diversity-biomass relationships for total plant species and for species representing different PFGs, and (viii) present an optimal range of biomass production at which herbaceous species diversity can be maintained at regional scale. Results obtained from this study revealed that each mountain plant community was characterised by unique herbaceous plant communities with specific indicator plant species, driven by soil properties and rainfall. Herbaceous plant composition, density, height, cover and shrub frequencies were related to a combination of soil properties and mean annual rainfall. However, plant diversity, and grass, lignified forb and tree frequencies, as well as woody plant height and canopy area, could only be related to soil properties. Grasses, lignified forbs and herbaceous forbs contributed to biomass production in descending order. At regional and local scales, diversity-productivity relationships followed non-linear trends. However, optimum biomass production was reached at highest diversity. Semi-arid mountain landscapes in GWC provide important ecosystem services through their unique plant diversity. It is necessary to follow a holistic, multi-disciplinary conservation and management approach to not only manage for species diversity, but to conserve the underlying environmental drivers in semi-arid mountain plant communities.
... Indicator plant species (Table 7) are characterized by high relative frequency of occurrence in a specific mountain habitat (specificity) and thus were primarily found in that habitat in high numbers (Dufrêne and Legendre 1997). In contrast to common species, indicator plant species provide valuable ecological information on various species groups of different plant communities (Dufrêne and Legendre 1997), especially with respect to their habitat preferences and adaptations to persist under certain environmental conditions (Siebert et al. 2010). ...
Van Staden N, Siebert SJ, Cilliers DP, Wilsenach D, Frisby AW. 2020. Floristic analysis of semi-arid mountain ecosystems of the Griqualand West centre of plant endemism, Northern Cape, South Africa. Biodiversitas 21: 1989-2002. The Griqualand West Centre (GWC) is one of 13 centres of plant endemism in South Africa. Despite its unique flora, it remains poorly conserved and studied. A recent study identified an extensive geographical core area for the GWC, but endemic plant species were found to be absent from certain parts within these borders. To address this, we refined the current GWC borders based on an ecological niche model, which predicted that endemic species are restricted to four mountain ranges within GWC. Mountain floras within these refined borders were then floristically compared to assess whether they are hotspots of endemicity. Floristically, the Asteraceae, Fabaceae, Malvaceae, and Poaceae were the dominant plant families. Mountain ecosystems differed from one another at species level, with indicator species explaining the compositional differences. Distribution patterns of indicator species were determined by mean annual precipitation, Ca: Mg ratios, soil pH, cation exchange capacity, iron, and sand content. These environmental factors are possible drivers of niche partitioning, environmental filtering and habitat specialization in each mountain ecosystem. Limestone and banded ironstone habitats were identified as conservation priority areas, since they contained the highest numbers of rare and threatened GWC restricted-range species, of which six were narrow endemics.
... Boloponera ikemkha was found within the Sekhukhuneland Centre of Plant Endemism (SCPE), an area recognised for its unique plant diversity (Siebert et al. 2002(Siebert et al. , 2010 but as yet very poorly known from an invertebrate perspective. The type locality of B. ikemkha is approximately 3400 km SSE of that of B. vicans (see Figure 5) and in a markedly different habitat with very different climatic conditions. ...
During an environmental impact assessment survey of a proposed tailings storage facility for a platinum mine in Sekhukhuneland, South Africa, five adult and five larval specimens of a new species of Boloponera were found while excavating soil to a depth of 10–15 cm at the base of a tree in riparian woodland. These specimens represent a 3400 km range extension and the first reported record of the genus since its description in 2006, which was based on a single specimen collected in the Central African Republic in 2001. A description of the worker and ergatoid queen of Boloponeraikemkhasp. n . is presented, with a description of the mature larva and a key to distinguish workers of the two currently known species of the genus. The taxonomic relationships of Boloponera are discussed with respect to several confirmed and newly identified autapomorphies that support its retention as a distinct genus, although closely related to Plectroctena and Loboponera . A preliminary assessment of the conservation status and discussion of potential threats to the survival of B.ikemkha is also provided. Evaluation of current data under the IUCN Red List criteria would result in B.ikemkha being assessed as Critically Endangered, but further investigation is required to test the validity of placing it in this category.
In this paper we celebrate this milestone by giving an overview of the history of the Department at this campus, including its recent establishment and expansion on the NWU Mahikeng Campus (formerly the University of NorthWest). A brief overview is presented of the advances in teaching and research over the years, and the development and relevance of the important plant collections in the botanical garden, two herbaria and the national diatom collection. The main emphasis of this contribution is, however, a reflection on the advance ment and significance of research conducted by various disciplines on plant and algae function, diversity and ecological restoration over the years. The different disciplines in Botany at NWU, from the oldest to the more recent, are Plant Taxonomy, Plant Ecophysiology, Terrestrial Plant Ecology, Aquatic Sci ences, Urban and Settlement Ecology, Geoecology, and Proteomics. Different aspects contributing to changes occurring in the environment, such as pollution, land degradation, urbanisation, overexploitation of resources and the subsequent effect of these on plant diversity and function are especially ad dressed in our current research. The results of our research inter alia led to solu tions for problems occurring in the landscape and contribute to the wellbeing of the people using the land and water by restoring important ecosystem services.
EXTENDED THESIS ABSTRACT Context Understanding spatial patterns of biodiversity and species’ distributions is important for scientific theory, and for conservation and management of the natural world. Climatic variables are widely recognised as strong correlates of species richness over large spatial extents. Correlates of species richness at smaller extents (regional and landscape scales) are less well established, but environmental heterogeneity is widely thought to be important. A large number of environmental heterogeneity measures have been used, but in particular there is a growing interest in ‘geodiversity’, which I define here as the diversity of abiotic terrestrial and hydrological nature, comprising earth surface materials and landforms. Recent research has emphasised both geodiversity’s inherent value and its potential as a correlate and predictor of spatial biodiversity and species’ distribution patterns. However, despite this clear potential of geodiversity for improving our understanding of how patterns of life relate to environmental heterogeneity, its incorporation into biodiversity and species’ distribution modelling is substantially underdeveloped. In this thesis, using a macroecological approach I begin to address some of these knowledge gaps by analysing the relationships between geodiversity data, and its constituent ‘geofeatures’, and species richness and distributions for multiple taxa and across several scales (grain size and extent) and geographic locations. My main aims in this thesis are to more fully evaluate geodiversity itself, and improve our understanding of its role with respect to the spatial patterning of biodiversity, both conceptually and empirically. Locations and Spatial Scales Analyses were carried out within and across Great Britain (England, Scotland, and Wales) and Finland. The order of the four quantitative papers generally reflects the largest spatial extent (i.e. size of the study area) at which they were conducted, from national (PAPERS II and III) through landscape (PAPER IV), to the local scale (vegetation plots within a small upland river catchment; PAPER V). PAPER II is a study across several spatial extents (from landscape to national) and uses two grain sizes (1 km2 and 100 km2). PAPER I is a review paper that considers multiple scales and geographic locations conceptually. Time period Present day: data were from between 1995 and 2016 across all of the quantitative studies. Taxa Multiple: alien and native vascular plants across Great Britain (PAPER II); threatened bryophytes, beetles, fungi, lepidoptera, lichens, mammals, molluscs, and vascular plants across Finland (PAPER III); common and rare vascular plants across the Cairngorms, Scotland (PAPER IV); angiosperms, conifers, fungi, lichens, liverworts, lycophytes, mosses, and pteridophytes (and productivity) across an upland river catchment within the Cairngorms (PAPER V); and conceptual consideration of multiple taxa (PAPER I). Methods For studies in Great Britain, plant data were provided by the Botanical Society of Britain and Ireland (BSBI) for PAPERS II and IV, and by the Centre for Ecology and Hydrology (CEH) for PAPER V. The threatened species data in Finland were from Finnish Environment Institute (PAPER II). Species richness (PAPERS II, III, and IV), rarity-weighted richness (RWR; PAPER III), species’ distributions (PAPERS IV and V), and productivity (measured using NDVI from colour infrared aerial imagery; PAPER V) were all analysed using Boosted Regression Tree (BRT) modelling, allowing comparisons between studies. For geodiversity data in the British studies, I compiled geodiversity data on landforms, soils, hydrological and geological features using existing national datasets (e.g. British Geological Survey), and used a geomorphometric method to extract landform coverage data (landforms included: hollows, ridges, valleys, and peaks). These data were analysed alongside environmental data, which varied between papers, relating to climate, standard topography (e.g. slope; elevation), land use, and human population. The sources of other geodiversity data in Finland, and environmental data on topography and climate, came from a variety of sources, which are detailed within each paper. Results Geodiversity improved biodiversity and species’ distribution models throughout all of the quantitative analyses and generally declined in importance as spatial scale coarsened beyond the landscape scale. At most spatial scales and in most places, the roles of climate and/or coarse topography dominated, and geodiversity played a relatively small role, as was expected. Geodiversity, however, made consistent positive contributions to the models independently of traditionally used topographic metrics such as standard deviation of elevation and slope. Taxonomically, geodiversity: (i) was slightly more relevant for native vascular plants than alien in Great Britain (PAPER II); (ii) of similar relevance to common and rare vascular plants in the Scottish Highlands, except that the coverage of soil parent material was especially important for rare species’ distributions (PAPER IV); of similar relevance to most sessile taxa (angiosperms, fungi, mosses, liverworts, lichens, pteridophytes, and lycophytes; conifers were not related to geodiversity) in an upland Scottish river catchment (PAPER V); and more important for threatened vascular plants and bryophytes over other studied taxa in Finland (PAPER II). Geodiversity also improved models of productivity, and the variability in productivity, in PAPER V. Main conclusions and Future Directions Geodiversity improves our understanding of, and ability to model, the relationship between biodiversity and environmental heterogeneity at multiple spatial scales, by allowing us to get closer to the real-world conditions and processes that affect life. I found that the greatest benefit comes from measuring ‘geofeatures’, which describe the constituent parts of geodiversity separately, rather than as one combined variable. Automatically extracted landform data, the use of which is novel in ecology, biogeography and macroecology, proved particularly valuable throughout this body of work, and as too did data from expert geological and hydrological maps. The idea of ‘Conserving Nature’s Stage’ (CNS), and identifying areas that are most capable of supporting high biodiversity into the future, the benefits and caveats of which are discussed in this thesis, has recently emerged. It requires a sound empirical and conceptual basis, to which my research contributes. In this thesis, I have gone some way towards demonstrating the conceptual and empirical value of incorporating geodiversity into ecological analyses across multiple spatial scales, paving the way for this recent approach to be more extensively used for theoretical and applied purposes. I accomplished this by carrying out an assessment of existing geodiversity literature and, importantly, looking forwards to consider the prospects of geodiversity within ecology (PAPER I), supported by four quantitative studies. The conservation significance is emphasised in PAPER III. Much remains to be done, however, and future research directions are detailed in PAPER I. We need to develop predictive models to test the role of geodiversity across an array of geographical and taxonomic domains, as well as to assess metrics beyond species richness and species’ distributions. One example may involve beta diversity: does spatial turnover in species relate to spatial turnover in geofeatures? Fully analysing the role of geodiversity through time will also be important, including in relation to refugia, given predicted environmental changes in climate. In progressing with this line of enquiry, we will improve our knowledge and understanding of patterns of life on Earth and, specifically, how the geophysical landscape helps shape them.
The first record of Polygala westii (Polygalaceae) from the North-West Province (South Africa) is reported on here. The species is very rare and has previously only been collected in two separate gatherings. This species is characterised by having bracts and bracteoles caducous, the anterior sepals connate at least as much as half of their length and seeds pubescent and carunculate. It grows in a habitat that are severely impacted by agriculture and mining. A preliminary assessment of its conservation status is given. A key to the South African species in the subsection (Tetrasepalae) to which P. westii belong is provided. The aim of this paper is to highlight the species in order to stimulate the lookout for more material of this species.
