Actually, mosses of the week. This pair of communities are part of my longitudinal study of mosses, some Cladonia chlorophaea lichens, and a few Lycopodium obscurum individuals. This is Site 3, community instances A and B.
Instance A is Platylomella lescurii (Pope, 2016, p 199, bottom, key only; Jenkins, 2021, p 141, habitat depicted on p 20, “Moss Map 8”). Instance B is Sphagnum fimbriatum (Pope, 2016, p 40, from the key on p 37; Jenkins, 2020, p 152). Instance A is interesting because the Platylomella suffered a good deal of erosion from flowing water even in the short time after I began observations, as can be seen below:
I captured an MP4 showing the oscillations in lescurii created by the flowing waters:
Jenkins (2020, p 141) says “found on rocks in streams, usually submerged a high water”. Platylomella is partly submerged here. A question is why does it erode since the habitat is suitable? Perhaps this is typical for Platylomella and permits it to propagate vegetatively? The other question is that the growth of this Platylomella community looks like it took more than a year. Why did it get eroded now? Or does it often get eroded and just grows back?
This kind of erosion at this stream isn’t limited to Platylomella. There is a Bryhnia novae-angliae at Site 3, instance D, which originally looked stable yet I reported it moved a meter on 13th January 2021.