Pennyroyal is one of a number of plants associated with seasonally wet habitats which have declined markedly over the last few decades. It is found in very short turf overlying clay and silt on sites that are subjected to grazing, trampling, dunging and general disturbance by livestock or vehicles. These conditions are often associated with traditionally managed lowland village greens, unmetalled trackways and the margins of ponds. Most remaining populations occur where there is rutting and poaching in the absence of hard grazing. The species is a short-lived perennial, that persists only where trampling enables stems to take root in the soil. Although seeds are produced, it is thought that very little recruitment takes place in this way.
In the UK, pennyroyal is now found in abundance only in the New Forest and on the western shores of Lough Beg in Northern Ireland. It has suffered one of the most severe and widespread declines of any species in the British flora over the last 50 years. Before 1970 it was known from 229 ten km squares, but has been recorded in only 15 of these since 1980. It is widespread in Europe where it is not threatened as a whole, but it is declining in many areas (eg Germany).
In GB this species is now classified as Vulnerable, and is specially protected under Schedule 8 of the Wildlife and Countryside Act 1981 and the Wildlife (NI) Order 1985.
Current factors causing loss or decline
The loss of seasonally wet habitats, either through drainage or excavation to create permanently wet conditions.
Abandonment or infilling of disturbed habitats favoured by pennyroyal, such as unmade tracks and gateways.
Cessation of traditional grazing management and subsequent successional changes.
Habitat destruction by agricultural intensification (such as fertilising or ploughing) and by development.
All known sites in Northern Ireland are within ASSIs.
Steps have been taken to ensure the continuation of beneficial pastoral management in the New Forest.
Action plan objectives and targets
Maintain the geographical range of pennyroyal in the UK.
Maintain viable populations at all extant sites in the UK.
Regenerate pennyroyal from the seed-bank on at least five suitable historic sites by 2003.
Establish an ex-situ programme to protect genetic diversity, create a reserve population and provide experimental material.
Proposed actions with lead agencies
Policy and legislation
Take account of the requirements of pennyroyal when developing new, or reviewing existing, environmental land management schemes that promote the traditional management of lowland commons and village greens. (ACTION: CCW, DANI, DETR, EHS, NE, LAs, MAFF, WOAD)
In contributing to any review of common land legislation, take into account the requirements of pennyroyal and other wet heath species. (ACTION: CCW, NE)
Site safeguard and management
Seek protection of all extant sites from damaging activities including infilling with hardcore, metalling of trackway sites, drainage and application of agro-chemicals. (ACTION: CCW, EHS, NE, FA, FE, MAFF, WOAD)
Ensure the long-term protection and appropriate management of all extant native sites. Where necessary to achieve this, consider notifying sites as SSSIs. (ACTION: CCW, EHS, NE, FA, FE)
Promote the continuation of traditional and beneficial forms of management, such as pony grazing, in the New Forest stronghold area. (ACTION: NE, FA, FE, MAFF)
Species management and protection
Undertake trial management on at least five suitable historic sites with the aim of regenerating plants from a possible seed-bank. (ACTION: NE)
Assess the feasibility and desirability of reintroducing pennyroyal at suitable historic sites should regeneration from the seed-bank prove unsuccessful. (ACTION: CCW, EHS, NE)
Collect seed from a representative number of sites throughout pennyroyal's range and deposit in the Millenium Seed Bank at Wakehurst Place (Kew). (ACTION: CCW, EHS, NE, RBG Kew)
Ensure that landowners and managers are aware of the presence and importance of this species and are advised on appropriate management. (ACTION: CCW, EHS, NE)
As far as possible, ensure that all relevant agri-environment project officers are advised of locations of this species, its importance and management needed for its conservation. (ACTION: CCW, DANI, EHS, NE, MAFF, WOAD)
Future Research and Monitoring
Re-survey all native sites which have not been surveyed in the last three years and where records have been made since 1970, in order to determine the current distribution and status of pennyroyal in the UK, ensure that management at each site is suitable and identify any potential threats. (ACTION: CCW, EHS, NE)
Undertake detailed monitoring and ecological research on three viable sites in different parts of the range of pennyroyal with a view to improving understanding of its requirements and refining management techniques for its conservation. (ACTION: CCW, EHS, NE)
Undertake regular monitoring on sites where populations have been restored. There should be a commitment to do this for at least 10 years. (ACTION: CCW, EHS, NE)
Collate information on the status of pennyroyal throughout Europe. (ACTION: JNCC)
Communications and Publicity
Generally promote the importance of ephemeral, muddy, superficially untidy habitats. Articles could be produced for the media. (ACTION: CCW, EHS, NE)
Links with other action plans
Originally published in: UK Biodiversity Group Tranche 2 Action Plans - Volume I: Vertebrates and vascular plants (June 1998, Tranche 2, Vol I, p209)
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