Linear-leaf Sugarbush

Taxonomy
Scientific Name
Protea decurrens E.Phillips
Higher Classification
Dicotyledons
Family
PROTEACEAE
Common Names
Linear-leaf Sugarbush (e)
National Status
Status and Criteria
Endangered B2ab(ii,iii,iv,v)
Assessment Date
2020/07/29
Assessor(s)
A.G. Rebelo, D. Raimondo & L. von Staden
Justification
Protea decurrens has a limited distribution range, with an extent of occurrence (EOO) of 8083 km², and area of occupancy (AOO) of 180-184 km². It has lost over 60% of its former habitat to agricultural expansion and the remaining subpopulations are severely fragmented. The population continues to decline due to ongoing habitat loss to crop cultivation, dense infestations of alien invasive plants, overgrazing and too frequent fires. Unexplained population declines have also been noted in some subpopulations. It therefore meets the thresholds for listing as Endangered under criterion B.
Distribution
Endemism
South African endemic
Provincial distribution
Western Cape
Range
This species is endemic to the Western Cape Province of South Africa, where it occurs from Shaw's Pass to the Langeberg Mountains.
Habitat and Ecology
Major system
Terrestrial
Major habitats
Mossel Bay Shale Renosterveld, Ruens Silcrete Renosterveld, Greyton Shale Fynbos, Potberg Ferricrete Fynbos, Elim Ferricrete Fynbos, Swellendam Silcrete Fynbos
Description
It grows in arid silcrete or ferricrete gravels along fynbos-renosterveld ecotones, at 40-550 m. 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 rodents.
Threats
Much of the lowlands of the Langeberg Mountains around Garcia's Pass have been planted with timber plantations, and the species' preferred habitat is targeted for wheat cultivation. About 61% of the habitat is irreversibly modified, and there is slow ongoing habitat loss due to agricultural expansion across this species' range. Other threats noted during field surveys include habitat degradation due to too frequent burning for grazing before plants set seed, for example the population at De Hoop declined from a few hundred individuals to only six between 1991 and 2002 due to burning of the population before it had set seed. Additional threats include overgrazing by livestock, and spread of alien invasive hakea and wattle species. Unexplained population declines have also been noted in some subpopulations.
Population

This species has lost the majority of its habitat to crop cultivation, and most subpopulations now remain in small remnants along road verges and between agricultural fields. It is known from 25 fragmented subpopulations, but over 50% of the population occurs as small and isolated stands of plants that are declining. The population is thus considered severely fragmented. Population decline continues due to habitat loss and degradation. The only large areas of intact habitat remaining are on the northern slopes of the Potberg, where between 300 and 500 plants are likely to be extant and the Bontebok Nature Reserve where the species has declined by over 90% in the past two generations due to too frequent burning.


Population trend
Decreasing
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Protea decurrens E.PhillipsNT A2c+3c; B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v)2020.1
Protea decurrens E.PhillipsEN B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v)Raimondo et al. (2009)
Protea decurrens E.PhillipsVulnerable Hilton-Taylor (1996)
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.


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.


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


Vlok, J. and Schutte-Vlok, A.L. 2010. Plants of the Klein Karoo. Umdaus Press, Hatfield.


Citation
Rebelo, A.G., Raimondo, D. & von Staden, L. 2020. Protea decurrens E.Phillips. National Assessment: Red List of South African Plants version . Accessed on 2024/04/20

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Distribution map

© J.H. Vlok/A.L. Schutte-Vlok

© J.H. Vlok/A.L. Schutte-Vlok


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