Long-term biomonitoring of lichen and bryophyte biodiversity at Burnham Beeches SAC and global environmental change

Abstract

Long-term monitoring began 20 years ago at Burnham Beeches Site of Special Interest (SSSI), National Nature Reserve (NNR) and European Special Area of Conservation (SAC) lying 40 km west of London as a consequence of the authorization of an application to extract gravel from an adjacent site lying north of Slough Trading Estate. Dust monitoring (sticky pads) and photographic monitoring, recording and image analysis was instigated in 1992 on Parmelion communities to assess changes in lichen growth, health and community composition. Long-term monitoring identifies that the lichen flora on free-standing trees has undergone rapid expansion from a near dominance by the SO₂-tolerant ‘acidophyte’ species Lecanora conizaeoides and Hypogymnia physodes following reductions in SO₂ concentrations. Long-term influences of low levels of eutrophication, gaseous pollutants (particularly globally rising background ozone concentrations) on lichen and bryophyte communities and succession under changing climatic conditions are unknown. Soil–plant relationships, lichen–invertebrate interactions and a pollution legacy must also be considered.

Key words:

• biomonitoring
• bryophyte
• climate change
• episode
• lichen
• pollution
• public policy

Acknowledgements

We dedicate the paper to the late Dr Francis Rose for his inspiration and for providing historical records. We are grateful to City of London for lichen monitoring contracts, a BM(NH) Student Vacationship to OWP and the Air Pollution Research in London (A.P.R.I.L.) network coordinated by Imperial College London. We thank Alison Catley and Rachel Evans (Slough Heat and Power) for providing SO₂ and NO_x monitoring data, Jim Storey (Environment Agency), Monica Wilsch (Slough Borough Council), Vanessa Pike (Research and Consultancy Office, NHM), NHM Photo Unit and staff, students, volunteers and others who have helped in so many different ways.