Grabouw Conebush

Taxonomy
Scientific Name
Leucadendron globosum (Kenn. ex Andrews) I.Williams
Higher Classification
Dicotyledons
Family
PROTEACEAE
Synonyms
Leucadendron ovale R.Br.
Common Names
Grabouw Conebush (e)
National Status
Status and Criteria
Critically Endangered A2ace; B1ab(iii,v); C2a(ii); D
Assessment Date
2020/04/23
Assessor(s)
A.G. Rebelo, D. Raimondo & L. von Staden
Justification
An endemic species that occurs only in Elgin Shale Fynbos Vegetation where it is restricted to one agricultural valley, in the mountains of the Western Cape Province, South Africa. Historically it occurred throughout the Elgin Valley but is now restricted to an extent of occurrence (EOO) of between 32 and 42 km² and an area of occupancy (AOO) of between 8 and 24 km². Over 71% of its former habitat has been irreversibly transformed for crop cultivation. Monitoring of stands of individuals remaining on fragments between fruit orchards since 1985 indicates that there has been a population reduction of between 96 and 99%. There are between two and six remaining subpopulations all with fewer than 10 plants. The total population numbers fewer than 50 individuals. The rapid collapse of the population of this species is due to remaining habitat being degraded by severe encroachment of woody invasive alien plant species and the change in vegetation structure from open fynbos to closed thicket vegetation due to lack of fire. Decline is projected to continue as farmers are highly reluctant to burn vegetation between fruit orchards. Without rapid intervention this species will be extinct within the next 10 to 20 years. It therefore qualifies as Critically Endangered under criteria A,B,C and D.
Distribution
Endemism
South African endemic
Provincial distribution
Western Cape
Range
This species is endemic to the Elgin Valley, in the Western Cape Province, South Africa.
Habitat and Ecology
Major system
Terrestrial
Major habitats
Elgin Shale Fynbos
Description
It occurs in loamy soils on steep, south-facing slopes, 220-300 m. Mature individuals are killed by fires, and only seeds survive. Seeds are released after ripening, and are stored in surface leaf-litter. It is dioecious, with insect-pollinated male and female flowers occuring on separate plants. This species generation length is linked to natural fire cycles and is between 15 and 20 years.
Threats
It once occurred throughout the Elgin valley, 71% of its former habitat has been irreversibly transformed for decidicuous fruit cultivation. It now remains only on remnants between orchards, and most of these are on steep, south facing slopes (too steep for fruit orchards) and are badly infested with pines, acacias and brambles. Due to lack of fire, thicket species are colonizing the remnants. With soil-stored seed banks, the presence of this species is difficult to ascertain in remnants which farmers are reticent to burn. There has been severe documented declines over the past 35 years as a result of lack of burning and competition from invasive alien plants.
Population

Historically there were probably three continuous subpopulations within the Elgin Basin, one in the north-eastern part of the valley, on along the north-western side and a third in the southern section. None of the herbarium record from the north-eastern former subpopulation were refound during the Protea Atlas project or subsequently, this entire subpopulation is extinct. From the north-western subpopulation only four plants were recorded from Palmiet River Bridge in 1996 and all these all were dead by 2007. This subpopulation is thus also extinct. The Southern subpopulation consisted of eight isolated stands of individuals in 1981. Two of these have been lost to planting of an fruit orchards, a further four are highly likely to be extinct due to severe infestation by pines and lack of burning in the tiny fragments they remain in, if there are still plants remaining at each of these site then each stand is likely to consist of fewer than 10 individuals. There are two fragments that have been recorded in 2017 to each have 3 plants in them. Since 1985 the population has decreased from 1300 plants (Hall and Veldhuis 1985), to the observed 6 plants and a possible maximum of 50 plants remaining in 2020. With a generation length of between 15 and 20 years, this represents a 96-99% decline over the past three generations. The numbers and population trends of the stands from the southern population are listed below. 1) Sutherland: In 1998 there were 24 plants (Forshaw 1998a), 13 in 2005, while no surveys have been conducted here there are likely fewer than 10 plants remaining in 2020 as a result of lack of burning. 2) Krabbefontein A: This is a 3 ha natural heritage site, there were 10 plants in 1989, with six remaining in 2002, from satellite imagery this fragment seems badly infested with invasive pines this stand is likely extinct. 3) Krabbefontein B: This is a 4 ha natural heritage site, 1100 plants were extant in 1985, a survey in 2007 revealed that the area had burned in the year 2000, resulting in a dense pine infestation with no visible plants of L. globosum remaining. Although a Heritage Site, the farmer could not afford to remove the pines and the area was up for sale in 2007. In 2020, from satellite imagery this tiny fragment looks badly invaded by invasive pine species there also appears to have been expansion of cultivation at the site. The subpopulation is likely to have been lost. 4) Lorraine/Oak Glen/ Elgin Orchards: This site was developed for fruit orchards by 1991. In 1992, there was a single male plant. In 2017, there were three plants seen, two are young, the farmer has agreed to clear and burn so there is a small chance that numbers here may increase. 5) Winterset: There were 10-100 plants in 1985, these are now extinct as the site was planted to fruit orchards in 1991. 6) DAL Investments: In 1991 there were six living plants and many dead individuals indicating that this population exceeded 100 in the 1980s. The site was infested with the dense pines that were being in 1991. In 1999 some three plants were found. This subpopulation is likely extinct in 2020 as there is no natural habitat remaining, it appears to have been ploughed. 7) Barkai: This is a 3 ha Natural Heritage Site declared in 1987. In 1991 some six plants and many skeletons occurred in moribund vegetation. In 1995 some six plants were seen, all in a fire belt. Tracer attempts to burn in May 2007 were unsuccessful as veld was too wet. While there have been no recent surveys here L. globosum is likely to have been lost as a result of lack of burning. 8) Deepdale farm, three plants seen in 2017.


Population trend
Decreasing
Conservation
Two Natural Heritage Sites have been proclaimed for this species, but these are not being burned frequently enough and have only a handful of live plants.
Notes
This species has high cultivation horticultural potential, but is not yet recorded in cultivation. Ex situ propagation and reintroduction work is urgently required to stop this species from going extinct.
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Leucadendron globosum (Kenn. ex Andrews) I.WilliamsCR A2c; B1ab(i,ii,iii,iv,v)c(iv)Raimondo et al. (2009)
Leucadendron globosum (Kenn. ex Andrews) I.WilliamsEndangered Hilton-Taylor (1996)
Leucadendron globosum (Kenn. ex Andrews) I.WilliamsVulnerable 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. and Veldhuis, R.N.J. 1985. South Arican red data book: Plants - Fynbos and Karoo biomes. South African National Scientific Programmes Report 117. 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.


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. & von Staden, L. 2020. Leucadendron globosum (Kenn. ex Andrews) I.Williams. National Assessment: Red List of South African Plants version . Accessed on 2025/05/29

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Distribution map

© C. Paterson-Jones

© C. Paterson-Jones

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