Taxonomy
Scientific Name
Euphorbia groenewaldii R.A.Dyer
Higher Classification
Dicotyledons
Family
EUPHORBIACEAE
National Status
Status and Criteria
Critically Endangered A4cd
Assessment Date
2022/07/20
Assessor(s)
N.N. Mhlongo, B. Egan, C. Rodgerson & L. von Staden
Justification
This species has a limited distribution near Polokwane, and is known from less than five locations. The population continues to decline due to urban development, quarrying, illegal collection and the effects of trampling and overgrazing. It has experienced a decline of 96% in one generation (generation length 20 years) and is projected to lose at least 10% of the remaining population within the next two generations. It therefore qualifies as Critically Endangered under criterion A.
Distribution
Endemism
South African endemic
Provincial distribution
Limpopo
Range
This species is endemic to the Limpopo Province, where it occurs near Polokwane.
Habitat and Ecology
Major system
Terrestrial
Major habitats
Mamabolo Mountain Bushveld, Polokwane Plateau Bushveld
Description
Plants grow on gentle, northwest-facing slopes of small granite hills and ridges between bands of schist or in gritty red sandy loam soil, 1100-1500 m.
Threats
The main threats to most remaining subpopulations are quarrying of schist and limestone for the construction of tar roads. Sand mining is a potential threat in some subpopulations, although it is currently only confined to the plains and on the hills in which this species occurs. The quartz on which this species grows is also collected for use at gravesites. Urban development is another major threat to this species, affecting many of the subpopulations. Housing developments in one of the subpopulations have expanded rapidly and houses have invaded the areas previously occupied by this species. The subpopulation near Polokwane is also threatened by housing developments and habitat on another farm is potentially threatened by destruction for a golf estate development. Two subpopulations are also in imminent danger of destruction through the expansion of an industrial brickworks site, that has already led to extensive declines at this site in the last 10 years. Infrastructure development (road construction) and building of a lodge could impact the largest subpopulation. All other subpopulations are small and might not be viable. A further locality was lost due to urban development around the 1980s; the locality is now a suburb of Polokwane. This species is also popular with succulent collectors, being a rare and endangered species, and collecting is likely to account for a significant proportion of the decline, but the exact extent is unknown. A subpopulation on one farm recorded in 1986 has disappeared, presumably because of over collecting. A recent survey in one of the sites (February 2022) suggested that harvesting was occurring in the area, with empty holes present where this species previously occurred and fewer plants were present than there were five years ago. Moderate grazing is not detrimental to the plants and therefore cattle and goats should not be excluded from these sites. However, grazing pressure should not be extreme as overstocking will lead to population decline due to trampling.
Population

This species is known from 10 subpopulations in less than five locations. Urban densification within this species' range has had a negative impact on individuals of this species. Developmental pressure has resulted in at least 10% of the population being lost within the last few years. Population surveys conducted between 1986 and 2007 recorded a 96% reduction in the number of mature individuals as a result of urban development, quarrying, severe overgrazing and harvesting for horticultural purposes. Two subpopulations recently surveyed had more than 1000 individuals at each site, growing between the schist and quartz rocks in the area. The plants were growing in short grass and had a good percentage of smaller individuals, indicating that recruitment was taking place. There was however an absence of large individuals, most likely the result of illegal collection targeting large individuals.


Population trend
Decreasing
Conservation
This species is not recorded from any formally protected areas.
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Euphorbia groenewaldii R.A.DyerCR A2acRaimondo et al. (2009)
Euphorbia groenewaldii R.A.DyerEndangered Hilton-Taylor (1996)
Euphorbia groenewaldii R.A.DyerVulnerable Hall et al. (1980)
Bibliography

Hall, A.V., De Winter, M., De Winter, B. and Van Oosterhout, S.A.M. 1980. Threatened plants of southern Africa. South African National Scienctific Programmes Report 45. CSIR, Pretoria.


Hilton-Taylor, C. 1996. Red data list of southern African plants. Strelitzia 4. South African National Botanical Institute, Pretoria.


Raimondo, D., von Staden, L., Foden, W., Victor, J.E., Helme, N.A., Turner, R.C., Kamundi, D.A. and Manyama, P.A. 2009. Red List of South African Plants. Strelitzia 25. South African National Biodiversity Institute, Pretoria.


Citation
Mhlongo, N.N., Egan, B., Rodgerson, C. & von Staden, L. 2022. Euphorbia groenewaldii R.A.Dyer. National Assessment: Red List of South African Plants version . Accessed on 2024/05/28

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Distribution map


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