You might expect the extensive, near mono-specific stands of Japanese Knotweed in Swansea to be one of the most unpromising bryo habitats...and you’d be right! A 20 minute search yesterday of one such stand, at Gors Avenue Quarry, Cwmbwrla (SS650945) produced just 16 species and failed to challenge this assumption. Not only were there virtually no other vascular plants represented in the field layer, the only niche where bryos were noted was on the very oldest decaying Knotweed root balls and quarry walls, but only where these were raised above ground level on what must be very old plants. For the record the only species noted were Brachythecium rutabulum, Calypogeia arguta, C.fissa, Kindbergia praelonga, Metzgeria furcata, Oxyrrhynchium hians & Pseudotaxiphyllum elegans.
The quarry walls provided a little bit of compensation and additional species noted included Diplophyllum albicans & Nardia scalaris.