Taxonomy
Scientific Name
Hereroa concava L.Bolus
Higher Classification
Dicotyledons
Family
AIZOACEAE
National Status
Status and Criteria
Vulnerable B1ab(iii)
Assessment Date
2020/02/06
Assessor(s)
D. Raimondo & L. von Staden
Justification
Hereroa concava is a rare and poorly known species with a restricted distribution range. Its extent of occurrence (EOO), calculated from herbarium specimen records, is 12 151 km², but is very uncertain. It is known from three to five locations, but is possibly overlooked. It is suspected to be declining due to ongoing habitat loss and degradation.
Distribution
Endemism
South African endemic
Provincial distribution
Northern Cape, Western Cape
Range
Due to taxonomic uncertainty, this species' distribution range is not well known. It appears to be endemic to a small area in the Great Karoo between Beaufort West, Richmond and De Aar.
Habitat and Ecology
Major system
Terrestrial
Major habitats
Eastern Upper Karoo, Upper Karoo Hardeveld
Description
Plants occur sheltered among shrubs on flats and plateaus with shale outcrops.
Threats
A large proportion of this species' known range falls within an area earmarked for shale gas fracking, which is likely to cause significant population decline if it is to go ahead. A Strategic Environmental Impact Assessment submitted to South Africa's Department of Environment Affairs in 2016 cautioned against the authorisation of shale gas fracking, based on the very high infrastructure costs associated with fracking as well as multiple secondary negative impacts both to biodiversity and other economic activities in the region. Furthermore, subsequent geological studies found that gas deposits are not as substantial as originally suspected due to the very old age of the Karoo shale formations, and the effect of widespread dolerite intrusions that resulted in much of the gas being lost. At present, future development scenarios are too uncertain to estimate the potential extent of the impact on the population but it is unlikely that shale gas fracking will proceed in the near future. In addition, this species' preferred habitat around Beaufort West is being lost to Uranium mining. Large parts of karoo vegetation is undergoing ongoing degradation due to a combination of severe overgrazing and prolonged droughts. This species is likely impacted by overgrazing outside protected areas, but field surveys are needed to confirm this.
Population

There are very few records of this species, scattered over a wide area. The most recent collection, dating from 1988 indicate that it is common in the Karoo National Park. Its abundance elsewhere is not known. It may be overlooked due to taxonomic uncertainty in Hereroa, and also because its range is botanically poorly explored. A continuing decline is inferred from ongoing habitat loss and degradation.


Population trend
Decreasing
Notes
Hereroa is urgently in need of taxonomic revision (Chesselet et al. 1995). Species are poorly known and difficult to identify with certainty.
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Hereroa concava L.BolusData Deficient Raimondo et al. (2009)
Bibliography

Chesselet, P., Mössmer, M. and Smith, G.F. 1995. Research priorities in the succulent plant family Mesembryanthemaceae Fenzl. South African Journal of Science 91:197-209.


Magee, A.R. and Boatwright, J.S. (eds). In prep. Plants of the Karoo: A Conspectus of the Nama-Karoo and Adjacent Summer-Rainfall Regions of the Northern and Western Cape Provinces. Strelitzia.


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
Raimondo, D. & von Staden, L. 2020. Hereroa concava L.Bolus. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2020/08/10

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Distribution map


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