Status, conservation and ecology of Pallavicinia lyellii (Hook.) Carruth. in a key region of England

ABSTRACT

Introduction. Pallavicinia lyellii is recognised as being of principal importance for conservation in England and is threatened with extinction in Europe. The aims of this study were to investigate the current status, conservation and ecology of the species in S Hampshire, a key region for the plant.

Methods. All recent and historic locations for Pallavicinia lyellii in S Hampshire were searched and information collected on distribution, abundance and ecology.

Results. Pallavicinia lyellii was re-found at three sites. It is almost certainly extinct at two sites and may have been lost from a third. Whilst few colonies were sterile, most comprised a single sex. Colonies with both male and female plants were confined to Cadnam Bog, which supported 49 (91%) of the colonies found. Overall, female shoots occurred at 41 (76%) colonies and males at 26 (48%), producing a female sex bias (1.6:1). All colonies occur in boggy woodland, mostly on the sides of low mounds of damp, acidic, peaty soil developed, due to poaching by ponies and cattle, at the base of trees, usually I. aquifolium. The community mainly comprises a species-poor mix of acidophilous mosses and liverworts, most frequently Mnium hornum, Pseudotaxiphyllum elegans and Leucobryum juniperoideum.

Conclusions. Cadnam Bog appears to support the largest sexually reproducing population of Pallavicinia lyellii in England. The site is specially protected, actively managed with consideration to P. lyellii and seemingly in favourable condition for the plant. Research is needed to quantify canopy shade favoured by the plant and assess implications for woodland management. Future monitoring should include re-survey of populations every 3 yr.

KEYWORDS:

• Habitat occupancy
• liverwort
• phenology
• phytosociology
• sex-ratio dynamics
• woodland management

Acknowledgements

Many thanks to Krisztina Fekete (Natural England) for managing the study contract, to John Norton and George Greiff for helping with some of the survey work, and to landowners for allowing site access. Thanks also to Jeff Duckett for insights into liverwort phenology, Jeff Bates for kindly compiling Figure 6, and to two anonymous reviewers for their helpful comments.

Notes on contributor

Des Callaghan is a consultant bryologist operating under Bryophyte Surveys Ltd, working throughout Britain and further afield. His research is focused on threatened species, taxonomy and conservation ecology.

ORCID

Des A. Callaghan http://orcid.org/0000-0002-0415-1493

Additional information

Funding

Funding for this study was provided by Natural England.