Population change in hyper-oceanic liverworts before and after hydroelectric power development: a preliminary study

ABSTRACT

Introduction. The best sites for oceanic bryophytes are typically in ravines that offer good potential for hydroelectric power (HEP) development. This preliminary study is the first to investigate population change in oceanic bryophytes of conservation concern at a site subject to HEP development.

Methods. Populations of five hyperoceanic liverworts were measured, Aphanolejeunea microscopica, Drepanolejeunea hamatifolia, Harpalejeunea molleri, Jubula hutchinsiae and Radula voluta, at two time periods, before and after HEP installation.

Results. Spanning almost four years, results reveal a dynamic system, with significant change in fine-scale distribution patterns, including many colony extinctions and colonisations. About 23% of colony losses of A. microscopica, D. hamatifolia and H. molleri appeared to result from exclusion by larger bryophytes, involving at least 17 species, in particular Ctenidium molluscum.

Conclusions. Inference with regards to effects of the HEP is not advised from this type of preliminary before and after study, based at a single site without controls. Given rapid recent growth of small HEP development and the enormous future potential, both in Britain and around the world, it is important to build upon this work and undertake comprehensive studies to detect possible impacts on bryophytes of conservation concern.

KEYWORDS:

• Before-after study
• bryophytes
• competitive exclusion
• gridded image plots
• HEP; hydroelectric power sites

Acknowledgements

Many thanks to the landowners for allowing access. Thanks also to Gideon Carpenter (NRW), Aled Lloyd (SNPA) and Dafydd Roberts (SNPA) for various help, and to two anonymous reviewers for their helpful comments. Information on HEP licences issued in Wales contains public sector information licenced under the Open Government Licence v3.0.

Notes on contributors

Des A. 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.

Sam D. S. Bosanquet is Non-vascular Plant Ecologist for Natural Resources Wales and bryophyte recorder for three Welsh vice-counties. His recent publications include Atlas of British and Irish Bryophytes (with three co-authors) (Pisces Publications 2014) and Guidelines for the Selection of Biological SSSIs, Part 2: Detailed Guidelines for Habitats and Species Groups, Chapter 12 Bryophytes (with two co-authors) (JNCC, 2018).

Rob Bissell is a Hydrologist at Natural Resources Wales. His work focuses on ensuring the sustainable management of water resources in North Wales, through data analysis and hydrological modelling of the surface water environment. His main areas of interest include abstraction licensing, river regulation, hydro-ecological investigations and flood frequency analysis.

ORCID

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

Rob Bissell http://orcid.org/0000-0003-1531-614X

Additional information

Funding

This work was supported by the Natural Resources Wales (NRW) and Snowdonia National Park Authority (SNPA).