Tower Mustard, Bwllpwllblod Y Ffwch BRASSICACEAE SYN.: Turritis Glabra (L.), Arabis Perfoliata Lam
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Arabis glabra (L.) Tower mustard, Bwllpwllblod y ffwch BRASSICACEAE SYN.: Turritis glabra (L.), Arabis perfoliata Lam. Status: Vulnerable Lead partner: Plantlife International Status in Europe: Not threatened 28 10-km squares post 1987 UK BAP Priority Species since 1998 UK Biodiversity Action Plan: The following are the current targets following the 2001 Targets Review: T1 - Maintain the natural range of this species in Britain. T2 - Establish populations at five sites within its historic range by 2008. T3 - Establish an ex-situ programme to protect genetic diversity, create a reserve population and to provide experimental material. Progress on targets as reported in the UKBAP 2002 reporting round can be viewed by selecting this species and logging in as a guest on the following web page: http://www.ukbap.org.uk/2002OnlineReport/mainframe.htm. The full Action Plan for Arabis glabra can be viewed on the following web page: http://www.ukbap.org.uk/UKPlans.aspx?ID=106. Contents 1 Morphology, Identification, Taxonomy & Genetics ............................................... 2 1.1 Morphology & Identification ............................................................................ 2 1.2 Taxonomic Considerations .............................................................................. 2 1.3 Genetic implications ...................................................................................... 3 2 Distribution & Current Status ........................................................................... 3 2.1 World .......................................................................................................... 3 2.2 Europe ........................................................................................................ 3 2.3 United Kingdom ............................................................................................ 5 2.3.1 England ................................................................................................... 6 2.3.2. Northern Ireland, Scotland & Wales ......................................................... 9 3 Ecology & Life Cycle ....................................................................................... 9 4 Habitat Requirements ................................................................................... 11 4.1 The Landscape Perspective........................................................................... 11 4.2 Communities & Vegetation ........................................................................... 11 4.3 Summary of Habitat Requirements ................................................................ 12 5 Management Implications.............................................................................. 14 6 Threats/ Factors leading to loss or decline or limiting recovery............................ 14 7 Current Conservation Measures...................................................................... 14 1 7.1 In Situ Measures........................................................................................ 14 7.2 Ex-Situ Measures ....................................................................................... 15 7.3 Research Data ............................................................................................ 16 7.4 Monitoring Arabis glabra and the Common Monitoring Standard......................... 16 8 References .................................................................................................. 16 9 Acknowledgments ........................................................................................ 17 10 Contacts ..................................................................................................... 17 11 Links .......................................................................................................... 18 1 Morphology, Identification, Taxonomy & Genetics 1.1 MORPHOLOGY & IDENTIFICATION Tufted biennial; stems erect to 1m, pubescent below, glabrous above; basal leaves entire to sinuate-lobed; flowers numerous; petals pale yellow (Stace, 1991). Seedpods are straight, four-angled siliquas with brown seeds in single rows under each valve (see Figures 1 & 2). Figure 1 – Arabis glabra flowers and Figure 2 – Close-up of Arabis glabra seedpods (Photograph by S. stem (Photograph by S. Williams). Williams). 1.2 TAXONOMIC CONSIDERATIONS None. 2 1.3 GENETIC IMPLICATIONS No studies on genetic diversity within this species have been carried out. Such a study would be desirable to elucidate relationships between populations, especially in the Brecklands. 2 Distribution & Current Status 2.1 WORLD In Europe, N. Asia, North America and Africa; introduced in Australia (Clapham et al, 1987), as illustrated in Figure 3 below. Figure 3 – The world distribution of Arabis glabra (Hulten & Fries, 1986). Reproduced with kind permission of Koeltz Scientific Books. 2.2 EUROPE Throughout Europe to 70o N in Norway (Clapham et al, 1987). Status in Europe - Not Threatened. Where known, the status of Arabis glabra in each country in Europe is given in Table 1. 3 Table 1 - Country by country status of Arabis glabra across Europe (*Country codes are taken from Flora Europaea as of 1964 with red data book listings where available [Definitions of the red list categories]). COUNTRY* IUCN STATUS NOTES SOURCE(S) LISTING Al ALBANIA Au AUSTRIA WITH LIECHTENSTEIN Az AZORES Be BELGIUM WITH LUXEMBOURG Bl ISLAS BALEARES Br BRITAIN INCL ORKNEY, VU Has declined strongly across Wigginton ZETLAND & ISLE OF MAN most of its British range, and is (1999). now known from only six sites in southern England, twelve in West Norfolk and a few in the West Midlands. Bu BULGARIA Co CORSE Cr KRITI WITH GAVDHOS KARPATHOS, & KASOS Cz CZECHOSLOVAKIA Bures et al Absent (2001). Da DENMARK Fa FAEROER Fe FINLAND INCLUDING Not listed Kotiranta et al AHVENANMAA (1998). Ga FRANCE Not listed Olivier et al (1995). Ge GERMANY Not listed Ingelog et al (1993). Gr GREECE EXCLUDING Not listed Phitos et al KRITI & ISLANDS OUTSIDE (1995). EUROPE Hb IRELAND BOTH NORTHERN IRELAND & THE REPUBLIC OF IRELAND He SWITZERLAND Not listed Antonietti (1991). Ho NETHERLANDS Hs SPAIN WITH GIBRALTAR & ANDORRA, EXCL BL Is ICELAND It ITALY Not listed Conti et al (1997). Ju YUGOSLAVIA Stevanović SERBIA Not listed (1999). Lu PORTUGAL No NORWAY Po POLAND Not listed Kaźmierczakowa & Zarzycki (2001). 4 COUNTRY* IUCN STATUS NOTES SOURCE(S) LISTING Rm ROMANIA Rs(N) NORTHERN Not listed Kotiranta et al DIVISION (1999). Rs(B) BALTIC Environmental DIVISION Protection Estonia Department of Latvia Not listed the Republic of Lithuania Lithuania (1992). Rs(C) CENTRAL DIVISION Rs(W) SOUTH- WESTERN DIVISION Rs(K) KRYM (CRIMEA) Rs(E) SOUTH-EASTERN DIVISION Sa SARDEGNA Sb SVALBARD (SPITSBERGEN BYORNOYA, JAN MAYEN) Si SICILIA Su SWEDEN Not listed Gärdenfors (2000). Tu TURKEY Not listed Ekim et al (2000). 2.3 UNITED KINGDOM OVERVIEW The British distribution of Arabis glabra is shown in Figure 4. Arabis glabra was formerly locally widespread in southeast England, the Midlands and East Anglia, with sites northwards to the Scottish Borders. Historic centres of distribution were in Yorkshire, the Midlands, East Anglia and the Thames Basin, and the current range reflects this, although no sites have been recorded in Yorkshire since 1972. Sites in Scotland and others in the north of England are considered to have been non-native, although the basis of this distinction is not known. Arabis glabra was extinct at all of these northern sites by 1900. The only site recorded in Wales was in Monmouthshire where it was last seen in 1900. 5 Figure 4 - British distribution of Arabis glabra. The total number of 10km squares from which Arabis glabra has been recorded is 133 (110 native and 23 non-native). This declined to 28 between 1987 and 1999 (26 native, 2 non- native), (Preston et al, 2002). The species was only recorded from 29 native sites in 20 10km squares during intensive survey work between 1996 and 1999 (Wheeler, 1999). The current area occupied by this species is only 15% of its total historic area. Stewart et al classed Arabis glabra as a Nationally Scarce species in 1994. It is now included on the priority list of the UK Biodiversity Action Plan (UK Biodiversity Steering Group, 1995), and is classified as a Vulnerable species in the UK, i.e. facing a high risk of extinction in the wild in the medium-term future, in the 3rd edition of the British Red Data Book of Vascular Plants (Wiggington, 1999). 2.3.1. ENGLAND (Based on English Nature’s Natural Areas) Arabis glabra appears to have declined considerably during the 20th century (see Table 2), although this is difficult to quantify precisely due to the seed bank that is thought to be very long-lived, and its habit of persisting for only short periods at some sites. A closer analysis of the records may show that it has been less abundant in the past than the distribution maps suggest. The great majority of losses from vice-counties occurred in the 19th century 6 and the first half of the 20th century (Wheeler, 1999), but losses from within its range have continued to the present day. The majority of extant sites are within the Breckland and Severn & Avon Vales Natural Areas. The major centre of distribution is in the East Anglian Breckland Natural Area. In this area it occurs largely in the rides and clearings associated with commercial forestry plantations established on former open heath and grassland in the early 20th century. It still grows on open sites such as Barnham Cross Common and Berners Heath, and it is