One of the recent attendees on BBS SE meetings is Nevil Hutchinson, and he has also joined BBS, so the two of us explored the southern part of Ditchling Common a couple of weeks ago. I only realised afterwards that Jacqui had already visited the tetrad, though as always is the case multiple visits clearly can reap rewards.
Starting off in the north-east corner of TQ31I we spent ages on a little track heading into the common. This was an ideal opportunity to see many common species, including the little acrocarps that grow in that habitat, such as Barbula unguiculata, Didymodon insulanus, Ceratodon purpureus, Funaria hygrometrica and Bryum dichotomum.
A few of the oaks dotted around the open space harboured some common epiphytes, and we spent a little while around the small bridge over the stream, where we found a Fossombronia, though it wasn’t fruiting unfortunately. Alongside the stream were some very pale clumps of Brachythecium albicans.
A small pond with willow harboured Cololejeunea minutissima, Fissidens bryoides and Eurhynchium striatum, and an iron drain by the B2112 was the rather surprising substrate for Zygodon conoideus.
Beginning to run out of time, we headed along the track towards Fragbarrow Farm, which turned up some of the most interesting species of the day, including Orthotrichum lyellii, Orthotrichum stramineum and Ulota phyllantha. Even so, there are still a few specimens that I’ve not identified, and they will be heading to Tom in due course.
Here’s a question, then: after how many hours visiting a tetrad can you be reasonably sure you’ve got, say, 95 per cent of the species in it?