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Sorbus subcuneata 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Magnoliopsida Rosales Rosaceae

Scientific Name: Sorbus subcuneata Wilmott
Common Name(s):
English Somerset Whitebeam
Taxonomic Source(s): The Plant List. 2017. The Plant List. Version 1.1. Available at: http://www.theplantlist.org/.

Assessment Information [top]

Red List Category & Criteria: Endangered D ver 3.1
Year Published: 2017
Date Assessed: 2015-07-31
Assessor(s): Rivers, M.C., Rich, T.C.G. & Beech, E.
Reviewer(s): Salvesen, P.H. & Allen, D.J.
Contributor(s): Wigginton, M.J.
Justification:
This species is restricted to the south coast of the Bristol Channel in England. It qualifies as Endangered (EN D), due to its low population size of 150 mature individuals. It has a highly restricted extent of occurrence and area of occupancy (<40 km2), there is an inferred continuing decline in quality and extent of habitat. Invasive species have been identified as out-competing individuals in one subpopulation, with a range of threats impacting other subpopulations.

Geographic Range [top]

Range Description:Sorbus subcuneata is confined to a small area along the north Devon and south Somerset coasts in England. The area of occupancy (AOO) will be less than 34 km2, however measured with the recommended 2x2 km grid, the AOO is 40 km2. The extent of occurrence is estimated at 34.5 km2, which is increased to 40 km2 to equal the AOO. The species occurs in six locations (Rich et al. 2010).
Countries occurrence:
Native:
United Kingdom (Great Britain)
Additional data:
Estimated area of occupancy (AOO) - km2:40Continuing decline in area of occupancy (AOO):No
Estimated extent of occurrence (EOO) - km2:40
Continuing decline in extent of occurrence (EOO):No
Number of Locations:6
Lower elevation limit (metres):1
Upper elevation limit (metres):250
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:There are around 300 trees at nine localities. The largest subpopulation is found at Watersmeet, Lyton with 270 trees (Rich et al. 2010). Most of the remaining small subpopulations are stable, with the one exception being the potentially threatened population above Minehead (Rich et al. 2010). There are about 150 mature individuals.
Current Population Trend:Stable
Additional data:
Number of mature individuals:150
All individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:This species is found as a small tree to at least 15 m in open rocky oak woodlands. Sometimes it occurs in more open hillside, scattered scrub and heathland. Soil pH ranges from acidic to neutral (Rich et al. 2010). Fruit set depends on proximity to other Sorbus species for the pseudogamous pollination (T. Hamston, unpublished data).
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes

Use and Trade [top]

Use and Trade: This species is not utilised.

Threats [top]

Major Threat(s): Above Minehead trees may be threatened by the invasion of Quercus ilex and Acer pseudoplatanus, shade tolerant species that may out compete it. Most Devon sites are thought to be relatively secure as they are in sites belonging to SSSIs or the National Trust (Rich et al. 2010). Fire and wood harvesting have also been recorded as possible threats (Wiggington 1998). Invasive Rhododendron ponticum is threatening regeneration along the coastal localities. High level of deer grazing at Watersmeet is limiting regeneration.

Conservation Actions [top]

Conservation Actions: Most of the sites in Devon occur within SSSIs (Site of Special Scientific Interest) or on land belonging to the National Trust and are therefore relatively secure (Rich et al. 2010). It was listed as Vulnerable by Cheffing and Farrell (2005) on the Red Data List for Great Britain and by Stroh et al. (2014) in the Red List of England. There are several ex situ collections in botanic gardens and arboreta around the world (BGCI 2015) and is recorded as present in an ex situ seed bank collection (ENSCO 2105). It is listed as a UK BAP priority vascular plant species (JNCC 2010).

Citation: Rivers, M.C., Rich, T.C.G. & Beech, E. 2017. Sorbus subcuneata. The IUCN Red List of Threatened Species 2017: e.T34722A80736635. . Downloaded on 23 November 2017.
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