The vertical distribution of lichens on the tower of St Stephens Church, Bath and the effect of scaffolding and air pollution

The aim of this project was to find out of scaffolding erected 11 months previously had a damaging effect on the lichen flora of the stone work of the tower. The lichens of the south face of the tower of St Stephens Church, Bath were sampled to find out species richness and cover with 10 x 10 cm quadrats and lobes of Caloplaca flavescens and Xanthoria paretina were taken for microscopic examination to determine the viability of the algal (photobiont) cells. The results do not indicate that the scaffolding caused any damage to the lichen flora although this is not conclusive as there was a marked change in the flora and the photobiont cells Caloplaca flavescens down the tower. The species richness and cover of lichens was less at the lower levels, where air pollution might be greater, than at the upper levels and the top above the scaffolding. The viability of photobiont cells in Caloplaca flavescens appeared to be better at the top than at the bottom as assessed by methylene blue staining. However these differences down the tower did not match the location of the scaffolding.