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 Mnium thomsonii (Crum, 2004, pp 256-259; Jenkins, 2021, p 88). Instance B is Sphagnum centrale (Pope, 2016, p 60; Crum 2004, pp 34-37; Jenkins, 2020, p 157). Instance A is interesting because the Mnium 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 M. thomsonii created by the flowing waters:

A question is why does it erode since the habitat is suitable? Perhaps this is typical for Mnium thomsonii and permits it to propagate vegetatively? The other question is that the growth of this Mnium 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 the Mnium. There is a Climacium americanum at Site 3, instance D, which originally looked stable yet I reported it moved a meter on 13^th January 2021. Emeritus Professor Janice Glime discusses the stream environment in Chapter 2 of Volume 4 of her mulivolume treatment of bryophyte ecology.