Sawedge Sugarbush

Taxonomy
Scientific Name
Protea holosericea (Salisb. ex Knight) Rourke
Higher Classification
Dicotyledons
Family
PROTEACEAE
Synonyms
Protea patens R.Br.
Common Names
Sawedge Sugarbush (e)
National Status
Status and Criteria
Critically Endangered A2acd; B1ab(iii,v)
Assessment Date
2020/07/06
Assessor(s)
A.G. Rebelo & D. Raimondo
Justification
Protea holosericea is a restricted endemic known to occur only on two mountain peaks in the Western Cape Province of South Africa. It is found at a single threat-defined location and has an extent of occurrence (EOO) and area of occupancy (A00) of 24 km². The population has declined by over 80% since 1982, as a result of harvesting of flowerheads, too infrequent fires, predation of seed heads and drought related mortality. With a generation length linked to natural fire cycles of between 15 and 20 years, this decline has taken place within the past two to three generations. It therefore qualifies for listing as Critically Endangered under criteria B and C.
Distribution
Endemism
South African endemic
Provincial distribution
Western Cape
Range
This species is restricted to the Kwadousberg Mountains in the Western Cape Province of South Africa.
Habitat and Ecology
Major system
Terrestrial
Major habitats
South Langeberg Sandstone Fynbos, North Langeberg Sandstone Fynbos
Description
It is found on steep, harsh, arid and extremely rocky areas, occurring at around 1200 m.a.s.l. Mature individuals are killed by fires, and only seeds survive. Wind-dispersed seeds are stored in fire-resistant inflorescences, and released after fires. It is pollinated by birds.
Threats
Wild flower harvesting was a threat in the past between 1980 and 1983, a farmer harvested over 8000 flowering heads. In 1984 harvesting was prohibited and there has been no harvesting since 1984. However monitoring data shows significant decline to the population following this harvesting. From observations made in 2015 and 2019, the population continues to decline as a result of heavy seed predation (most likely baboons), too infrequent fires also appear to be a concern, with the last fire recorded by CapeNature to have been in the year 2000. Lack of burning results in plants senescing and seeds and seedheads being predated. Furthermore the population appears to be declining due to drought conditions which are linked to climate change aridification trends as predicted by Climate Change models for the Western Cape.
Population

There is only one subpopulation of this species that occurs as three stands, all found within a 2 km radius of one another. The Sawedge Peak, Patryskloof stand had 1000 plants in 1982, in 1992 about 80-100 plants. During 1992-1998 between 100 and 200 were seen. The Sawedge Peak, Paardekloof stand had 500 mature individuals in 1982, in 1992 the plants could not be counted because of fire in 1988. Between 1992 and 1999 10-100 plants were counted. Neither of the Sawedge peak stands have been monitored in the past 20 years but are suspected to be declining. The third stand on the Rabiesberg had over 1000 plants extending on both the western and south-eastern ridges of the mountain for over four kilometres but with most of the plants concentrated on the top of the peak, this site was visited in 2015 and only five plants found, and again in 2019 when only one plant was found along with 6 dead skeletons. These two recent observations suggest significant decline has taken place at this stand. The above monitoring data indicates that the population had at least 2500 plants in 1982, by 1998 the population had declined to an estimated 1300 mature individuals and by 2015 fewer than 500 plants are extrapolated to be extant.


Population trend
Decreasing
Conservation
It is not currently conserved in any formally protected area.
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Protea holosericea (Salisb. ex Knight) RourkeEN B1ac(iv)+2ac(iv)Raimondo et al. (2009)
Protea holosericea (Salisb. ex Knight) RourkeRare Hilton-Taylor (1996)
Protea holosericea (Salisb. ex Knight) RourkeEndangered Hall et al. (1980)
Bibliography

Goldblatt, P. and Manning, J.C. 2000. Cape Plants: A conspectus of the Cape Flora of South Africa. Strelitzia 9. National Botanical Institute, Cape Town.


Hall, A.V. 1982. Rare plants Gazette No 1. February 1982. Bolus Herbarium, University of Cape Town.


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.


Manning, J.C. and Goldblatt, P. 2012. Plants of the Greater Cape Floristic Region 1: The Core Cape Flora. Strelitzia 29. South African National Biodiversity 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.


Rebelo, T. 2001. Sasol Proteas: A field guide to the proteas of southern Africa. (2nd ed.). Fernwood Press, Vlaeberg, Cape Town.


Citation
Rebelo, A.G. & Raimondo, D. 2020. Protea holosericea (Salisb. ex Knight) Rourke. National Assessment: Red List of South African Plants version . Accessed on 2024/04/17

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Distribution map

© C. Paterson-Jones


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