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Berula burchellii 

Scope: Global
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Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Magnoliopsida Apiales Umbelliferae

Scientific Name: Berula burchellii
Species Authority: (Hook.f.) Spalik & S.R.Downie
Common Name(s):
English Dwarf Jellico
Synonym(s):
Lichtensteinia burchellii Hook.f.
Sium burchellii (Hook.f.) Hemsl.
Taxonomic Notes: Very close to Berula bracteata, and formerly considered by some Botanists to be a dwarf variant of B. bracteata, but growth habit and fruit clearly distinguish the two species (Cronk 2000). Cronk (2000) also remarks that the two Berula (Sium) species kept their distinctive characteristics when grown side by side from seed in the Temperate House at the Royal Botanic Gardens, Kew. Hybridization is suspected but not confirmed and further study is needed.

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(iii,v)+2ab(iii,v) ver 3.1
Year Published: 2016
Date Assessed: 2015-06-10
Assessor(s): Lambdon, P.W. & Ellick, S.
Reviewer(s): Maxted, N. & Clubbe, C.P.
Contributor(s): Cairns-Wicks, R.
Justification:
The world range of Dwarf Jellico (Berula burchellii) is very small, with a large majority of the population confined to a single site. The number of individuals is too large to qualify as Endangered under criteria C or D, but it meets the requirements under criterion B: In addition to the limited extent of occurrence and few locations, there is reasonable evidence of decline in at least the outlying subpopulations, which are currently threatened with extirpation.

The species was last assessed in 2003 (Cairns-Wicks 2003), when it was also considered to be Endangered under criterion D.  This option has now been dropped because more comprehensive census data has revealed the world population to be larger than previously thought. However, the new information points to alternative threats which are equally as acute as those previously documented.
Previously published Red List assessments:

Geographic Range [top]

Range Description:

Dwarf Jellico is endemic to the island of St Helena, South Atlantic Ocean, where it is confined to a few scattered localities along the crest of the Central Ridge.

The extent of occurrence (EOO), based on the area of a minimum convex polygon around known localities, is 1.38 km2. The area of occupancy (AOO), based on a 2 km × 2 km grid, is 12 km2. Following IUCN Red List Guidelines, the EOO is therefore increased to 12 km2 to match the AOO.

The major stronghold is on the south-facing cliffs of High Peak, which extend laterally for little more than 200 m. Small populations clusters continue westward along the Central Ridge for approximately another 1 km, dotting the exposed low crags just below the crest as far as The Depot, where a further windswept cliff hosts another small concentration. The species is almost absent from the eastern part of the Central Ridge except for very few plants in the Diana’s Peak area. At present, only a small clump on Taylor’s Flat and a thin scattering on the cliffs at Wash House are recorded with certainty, but it is not entirely clear whether any of these are naturally occurring or were established from cultivation in recent decades. Dwarf Jellico was introduced to a number of localities across Diana’s Peak National Park in the 1990s. Further small numbers on the western escarpment of Cuckold’s Point and Mt Actaeon could perhaps be hybrids with the larger relative, Jellico (Berula bracteata (Roxb.) Spalik & S.R.Downie). Excluding these, the surveyed sites occupy a total area of less than 2 ha. Cronk (2000) noted a subpopulation on cliffs near Rose Cottage, but this area has not been visited recently.

Countries occurrence:
Native:
Saint Helena, Ascension and Tristan da Cunha (Saint Helena (main island))
Additional data:
Estimated area of occupancy (AOO) - km2:12Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:12
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:2Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:NoLower elevation limit (metres):720
Upper elevation limit (metres):820
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:

A census conducted in 2013 – 14 estimated the world population to comprise 6,423 individuals (approximate 95% confidence range: 3,237 – 10,860). The colony at High Peak accounted for 94.2% of this, with 1.5% at The Depot and 2.8% more widely dispersed between these two focal areas along Red Rock Ridge. Only 26 plants were found at Taylor’s and 68 divided between 3 – 4 patches at Wash House.

During the most recent previous assessment, Cairns-Wicks (2003) considered that all subpopulations consisted of less than 50 individuals. At the time, this was a reasonable assumption, because a large part of the total population survives on barely accessible cliff ledges hidden from view from most suitable vantage points. However, further investigation using ropes to access the main cliffs areas has revealed a more optimistic situation. Unfortunately, the possible locality near Rose Cottage was not visited.

Due to the scarcity of previous records, insufficient information remains to assess whether there have been pronounced changes in the population in recent history. The High Peak subpopulation has probably been relatively stable for some time. In contrast, there are some indications that the outlying patches on Diana’s Peak Ridge have dwindled. In the 19th Century, Melliss (1875) knew Dwarf Jellico from the western slopes near Diana’s Peak where it is unlikely to persist. It was also reported from the cliffs below Taylor’s Flat (the “Purgatory” area) in the 1990s (Cairns-Wicks 2003), but attempts to relocate this colony recently were impeded by overgrown vegetation. A photographic survey failed to detect any signs, although the sister species, Jellico, also occurs here in small quantities and some confusion over identity may have occurred. In 2008, a few plants were known on the western side of Mt Actaeon (the most northerly of the three peaks along the ridge), which do not appear to have survived, and it also seems likely that the Wash House subpopulation has decreased since 2008, despite the fact that the wider survey discovered additional patches as a whole in this area.

Current Population Trend:Decreasing
Additional data:
Number of mature individuals:6423Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:2-3Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:

Dwarf Jellico is a plant of earthy cliff ledges which receive large amounts of moisture from incoming mists. It is very resilient against the strong winds which regularly scour the western Central Ridge, and will grow either on bare rocky faces or amongst dense herbaceous vegetation in more sheltered situations, where it co-occurs with numerous other endemic species such as Diana’s Peak Grass (Carex dianae Steud.), Lobelia (Trimeris scaevolifolia (Roxb.) Mabb.) and Lays-Back Fern (Pteris paleacea Roxb.). It will occasionally grow under the heavily-shaded canopy of Black Cabbage Tree (Melanodendron integrifolium (Roxb.) DC.) or under New Zealand Flax plantation (Phormium tenax J.R.Forst. & G.Forst.). A few of the patches around the Diana’s Peak area are found amongst the thick, acidic litter of Tree Ferns (Dicksonia arborescens L’Hér).

Plants flower en masse in summer, producing abundant seed a few months later. The seed appears to have reasonably high fertility although insect pollinators are relatively scarce in the cool, windy conditions of High Peak. The stigmas may be partially self-fertilized by the in-curling stamens.

Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes
Movement patterns:Not a Migrant

Threats [top]

Major Threat(s):

It is unclear whether the current western bias of the species reflects the original distribution (i.e., that prevailing before humans settled St Helena in the 1600s) although it is likely that Dwarf Jellico was more widespread along the crags of the Central Ridge at one time. Establishment of extensive New Zealand Flax plantations over many of the steepest slopes in the first half of the 20th Century would undoubtedly have removed much potentially suitable habitat. However, there were scant records even before this. Deforestation for timber, and removal of native cloud forest habitat to make way for pasture, may have reduced the population to fragments before botanical records were made on the island.

Overall, the limited numbers of plants found in the Diana’s Peak area, and their advanced state of fragmentation, make it highly likely that the species will eventually be lost from the eastern Central Ridge in coming decades. Current numbers clearly represent only a fraction of the 800 seedlings which were introduced in 1996 (Cairns-Wicks, 2003). The main threats appear to stem from heavy infestations of non-native plants in suitable habitat. The steep western escarpments of Diana’s Peak have been largely overgrown by tall invasive species such as Whiteweed (Austroeupatorium inulifolium (Kunth) R.M.King & H.Rob.), Bilberrry Tree (Solanum mauritianum Scop.), Smokebush Buddleja (Buddleja madagascariensis Lam.) and New Zealand Flax. In addition to this hazard, there is a strong suspicion that the species has hybridized with the much larger Jellico, which is still reasonably widespread in the eastern Peaks. Possible hybrids were reported in 2003 (Cairns-Wicks 2003) and a number of dubious individuals still exist around Taylor’s Flat.

At present, there are fewer immediate threats facing the western strongholds, though some of the Red Rock fragments are small and could be overgrown by dense swards of pasture grasses which appear to be advancing on the crags. Fortunately, the cliffs of High Peaks remain relatively free of invasive infestations. In the future however, the situation could be transformed for the worse if problematic weeds were to gain a foothold in the core habitats. There is a pressing danger of this, since two very aggressive non-natives, which are already a major nuisance elsewhere in the cloud forest zone, have now advanced their range to within very close proximity. Small Fuschia (Fuchsia coccinea Curt.) and Pheasant-Tail Fern (Nephrolepis cordifolia (L.) C.Presl) both form very extensive, smothering growths, and at least in the former case, seedlings have already been detected growing on remote parts of High Peak face.

The hybridization issue also affects the western population stronghold. An extensive area of plants which appear completely intermediate between the parents have been present at High Peak since the 1950s (Kerr 1970). These are not known to have spread outside a single colony, but the hybrid form is clearly capable of reproducing effectively and should they succeed in back-crossing to plants at other localities, there is a risk that the integrity of the population could be compromised.

Conservation Actions [top]

Conservation Actions:

The entire population of Dwarf Jellico lies within the Central Peaks National Park (part of the recently designated National Conservation Area network), and will be protected under the National Conservation Area development plans, which are expected to be in place in 2016. The species will also be protected under the new Environmental Protection Ordinance, presently in the final stages of drafting and also expected to be issued in 2016.

Dwarf Jellico grows well in cultivation. St Helena Government’s Environmental Conservation Section currently achieve a reasonable production of nursery-grown plants, and plentiful seed has been banked on-island and at Kew's Millennium Seed Bank in the UK. However, further attempts to reintroduce plants to the eastern Peaks have lost impetus due to the threat of hybridization. More detailed studies would be highly valuable to determine the identity of the putative hybrids and their pollination ecology, in order to develop a strategy for managing the risks effectively.

High Peak currently receives little direct conservation effort, although the St Helena National Trust have recently initiated habitat restoration projects on part of the site, funded by the Darwin Initiative. Early trials suggest that  Dwarf Jellico is an excellent option for re-establishing native ground cover on eroded soils. Never the less, if this progress is to be maintained, preventative action to address the build-up of Small Fuchsia and Pheasant-Tail Fern on the western Central Ridge are much needed.


Citation: Lambdon, P.W. & Ellick, S. 2016. Berula burchellii. The IUCN Red List of Threatened Species 2016: e.T43986A67378501. . Downloaded on 26 August 2016.
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