Pygmy Porkbush

Taxonomy
Scientific Name
Portulacaria pygmaea Pillans
Higher Classification
Dicotyledons
Family
DIDIEREACEAE
Synonyms
Ceraria pygmaea (Pillans) G.D.Rowley
Common Names
Pygmy Porkbush (e)
National Status
Status and Criteria
Critically Endangered A2acd+4acd
Assessment Date
2022/07/27
Assessor(s)
N.N. Mhlongo, L. von Staden & P.C.V. Van Wyk
Justification
This species has lost more than 80% of its habitat due to open-cast mining since 1995, and it is projected that a further 15% will be lost in the next 15 years. The remaining population is highly threatened by illegal collecting for the specialist succulent trade and drought related to climate change. It is long-lived, with a generation length of at least 100 years, and recruitment is uncommon. Therefore, it qualifies as Critically Endangered under criterion A.
Distribution
Endemism
Not endemic to South Africa
Provincial distribution
Northern Cape
Range
This species occurs in the Richtersveld in the Northern Cape Province of South Africa and in southern Namibia.
Habitat and Ecology
Major system
Terrestrial
Major habitats
Western Gariep Hills Desert, Western Gariep Lowland Desert, Noms Mountain Desert
Description
Plants grow on low hills and quartz flats. It has very specific habitat requirements: 90% of the population occurs on alluvial deposits of the Proto and Meso terraces along the Orange River, the remaining 10% is found on quartz and shale.
Threats
The primary threat to this species is drought, followed by habitat loss due to mining; however, it is expected that illegal harvesting will soon become the leading threat. The population is rapidly declining due to illegal collection, with over 4000 plants included in confiscations in South Africa between March 2019 and July 2022. Many more are likely to have been removed from the wild but not intercepted by law enforcement efforts. Furthermore, more than 6500 plants suspected to be of wild origin were exported from a South African nursery between 2011 and 2018. Around Sendelingsdrif, it faces ongoing habitat loss and degradation due to open-cast mining. Dust blowing from exposed mining sites is particularly detrimental to the quartz field habitat of this species, burying surface quartz pebbles and destroying the micro-habitat required by many dwarf succulents to survive. The impact of this degradation can extend for several kilometers beyond the borders of the mining site. Between Alexander Bay and Sendelingsdrif, it is also threatened by ongoing habitat degradation, erosion, and trampling resulting from severe overstocking of rangelands with livestock. The species has suffered a drastic decline due to the worst drought recorded, which began in 2012 and is ongoing at the time of the assessment.
Population

A rare and localized species in South Africa, it is declining across its range. It is also rare in Namibia, though this may be due to under-sampling, as its habitat remains relatively poorly explored botanically. The species has been severely impacted by drought-related mortality, resulting in the loss of more than half of the population since 2016 across its range. Within South Africa, approximately 70% of its habitat was lost to mining between 1995 and 2015. An additional 10% was lost after 2015, and it is projected that mining expansions will lead to another 15% loss within the South African range by 2037. Similar levels of loss are expected for the Namibian population. The species exhibits variation in growth form, which can be divided into three zones from the east to the west, following the Orange River. It is a long-lived species, with individuals capable of surviving for up to 200 years. The generation length is suspected to be at least 100 years. Recruitment is sporadic, occurring on average once in over 30 years. Notably, no seedlings have been observed over a 12-year period (2010-2022).


Population trend
Decreasing
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Portulacaria pygmaea PillansEN B1ab(iii,v)2015.1
Ceraria pygmaea (Pillans) G.D.RowleyLeast Concern 2011.1
Bibliography

Bruyns, P.V., Oliveira-Neto, M., Melo-de-Pinna, G.F. and Klak, C. 2014. Phylogenetic relationships in the Didiereaceae with special reference to subfamily Portulacarioideae. Taxon 63(5):1053-1064.


Snijman, D.A. 2013. Plants of the Greater Cape Floristic Region 2: The extra Cape flora. Strelitzia 30. South African National Biodiversity Institute, Pretoria.


Citation
Mhlongo, N.N., von Staden, L. & Van Wyk, P.C.V. 2022. Portulacaria pygmaea Pillans. National Assessment: Red List of South African Plants version . Accessed on 2024/06/14

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Distribution map

© L. von Staden


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