Medium Excitement

Yesterday I took a quickish walk with Jonathan Saville to a bog on Mynydd Llangattock to download data from some dipwell loggers.   The bog has changed considerably since I first visited in about 1999.  Back then, this common was quite heavily grazed and much of the bog surface consisted of scattered tightly grazed patches of vegetation with more bare peat than vegetation and hardly any Sphagnum, although there were strong populations of round-leaved sundew Drosera rotundifolia growing on the peat and Splachnum sphaericum growing on the abundant animal droppings.   The area was also suffering from the effects of a deep drainage ditch, almost a canal, which had been dug through the middle of the bog to feed the Garnlydan reservoir, and no doubt the site was also being affected by the poorer air conditions back then - the Ebbw Vale Steels Works only 7km to the south was just about still working then.       


Twenty years on, the area looks very different – grazing levels are much reduced and the ditch has largely filled in.  There is now almost a complete cover of vegetation, with a nice mix of bog plants and an abundance of Sphagnum, including much S. papillosum.    

About 7 years ago I managed to refind a mid 1970s record of Bog Rosemary Andromeda polifolia somewhere on this bog -  I walked over to a colleague to share the excitement and then walked back and couldn't find it again! 


Whilst discussing the vegetation changes with Jonathan I suggested that it would be wonderful if, before he retires, he finds S. magellanicum growing on this bog – as it happens we didn’t have to wait that long as a few minutes later we bumped into a large patch of the moss. 

There are very few records of S. magellanicum in south Wales and at most of the sites where it does occur there is often only a tiny population of one patch or so.  Mynydd Llangattock is a good distance from the next nearest sites in N. Brecks and Carmarthenshire and I presume it has colonised since my first visit.   
        

After 40 years of making references to Sphagnum magellanicum it might take me a long time to get used to calling our plant of ombrotrophic bogs S. medium.  If anyone missed the paper in the Journal of Bryology a couple of years back a summary is given here: https://www.tandfonline.com/doi/abs/10.1080/03736687.2018.1474424