Petrifying springs in Wales

Most bryologists are familiar with
petrifying or ‘tufa’ springs as they
are a habitat where bryophytes
often predominate. In Britain, these springs
and seepages are often associated with the
pleurocarpous moss Palustriella commutata. The
importance of petrifying springs in Europe is
further highlighted by their inclusion within
the EC Habitats Directive (92/43/EEC) as the
Annex 1 habitat: H7220 Petrifying springs with
tufa formation (Cratoneurion). The authors
were commissioned by Natural Resources Wales
(NRW) to survey a range of Welsh sites; the aim
was to provide a baseline dataset for the habitat,
whilst also fulfilling the EC Habitat Directive’s
requirement to record the condition of this
Annex 1 habitat (see Farr et al., 2014).
Twenty seven sites at fifteen locations were
surveyed during November 2013 and January
2014, a wet but not exceptionally cold Welsh
winter. The sites ranged from natural locations
such as the vertical cliff seepage faces on the
Anglesey coastline (Fig. 1) to those highly
influenced by historic anthropogenic activities.
An example of the later was a site associated with
highly calcareous, hyperalkaline (>pH 12) waters
leaching from the base of spoil heaps at Herbert’s
Quarry, Mynydd Du (The Black Mountain)
(Fig. 2).
From the outset, the project aimed to combine
both botanical and hydrogeological investigations
of the sites including: species-richness, water
chemistry, water supply mechanisms, geological
setting and identification of land use pressures.