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Sorbus vexans 

Scope: Global
Language: English
Status_ne_offStatus_dd_offStatus_lc_offStatus_nt_offStatus_vu_offStatus_en_offStatus_cr_onStatus_ew_offStatus_ex_off

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Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Magnoliopsida Rosales Rosaceae

Scientific Name: Sorbus vexans E.F.Warb.
Common Name(s):
English Bloody 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: Critically Endangered D ver 3.1
Year Published: 2017
Date Assessed: 2015-11-16
Assessor(s): Beech, E., Rich, T.C.G. & Rivers, M.C.
Reviewer(s): Salvesen, P.H. & Allen, D.J.
Contributor(s): Wigginton, M.J.
Justification:
Sorbus vexans is a shrub or small tree with a restricted distribution in South West England. It qualifies as Critically Endangered (CR D) as it has a population of about 35 mature individuals. There is a need for a full survey of the area to determine accurate population numbers. It is also a range-restricted species with an extent of occurrence of 16 km2, however the threats to this species are not fully understood and there is no evidence of continuing decline.

Geographic Range [top]

Range Description:This species occurs along a small corridor of coast between Culbone in Somerset and an area just west of Trentishoe in Devon (Rich et al. 2010) in southwestern England. It has an estimated extent of occurrence (EOO) of 18.4 km2. The area of occupancy has not been estimated but is also likely to be restricted.
Countries occurrence:
Native:
United Kingdom (Great Britain)
Additional data:
Continuing decline in extent of occurrence (EOO):Unknown
Lower elevation limit (metres):10
Upper elevation limit (metres):200
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:There are several small populations of this species which are spread across its range. The number of individuals in each population ranges from 1-28. The total known population is 70 individuals, however it is likely there are more in surrounding habitat (Rich et al. 2010). The number of mature individuals is about 35. The population is thought to be stable although appears to be dynamic (Rich et al. 2010).
Current Population Trend:Stable
Additional data:
Number of mature individuals:35Continuing decline of mature individuals:No
Extreme fluctuations:NoPopulation severely fragmented:No
All individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:A shrub or small tree, to at least 10 m which is often multi-stemmed from the base. The species grows mainly in open oak woodlands but is also found on open rocks and heathland. It grows to its tallest in the woodland, and in more exposed areas is often found as a shrub of 2 m. It is apomictic. It has erratic fruiting and there are frequent young saplings (Rich et al. 2010).
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:No

Use and Trade [top]

Use and Trade: The species is not utilised.

Threats [top]

Major Threat(s): There are no obvious widespread threats to the populations, although inappropriate woodland management and the spread of Rhododendron are potential hazards (Anon. 2009). Deer grazing and woodland closure threaten some subpopulations.

Conservation Actions [top]

Conservation Actions: Sorbus vexans is reported as held in 11 ex situ collections (BGCI 2015) some of which need verification. It is recorded as present in an ex situ seed bank collection (ENSCO 2015). The species occurs within several protected areas across its distribution e.g., the Watersmeet and Exmoor Coastal Heaths Sites of Special Scientific Interest (SSSI).

This species is listed as Endangered in The vascular plant Red Data List for Great Britain (Cheffings and Farrell 2005) and The Red List of England (Stroh et al. 2014). It was listed as Vulnerable in Oldfield et al. (1998). It is listed as a UK BAP priority vascular plant species (JNCC 2010). There is a need for a full survey of the area to determine accurate population numbers (Rich et al. 2010). A PhD studying its conservation is nearing completion (T. Hamston pers. comm. 2016).


Citation: Beech, E., Rich, T.C.G. & Rivers, M.C. 2017. Sorbus vexans. The IUCN Red List of Threatened Species 2017: e.T34725A80736740. . Downloaded on 15 December 2017.
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