This rare moss can grow whilst completely or partly submerged in water. It resembles several other members of the sphagnum moss family and ranges from dull green to orange in colour. It can form large floating mats under the right conditions but, typically, occurs as scattered shoots amongst other bog mosses.
Recent studies of this moss suggest that it might be what is called a ‘colonist’ species. This means it is amongst the first species to colonise a new site. However, it does not appear to be a competitive species, so when other mosses and higher plants move on to the site, Baltic bog moss disappears.
It has been recorded from seven different and widely scattered sites in the UK, and it seems it has disappeared from four of these. In England there are three recorded sites, in Cheshire (from where it has not been seen for over a century), Yorkshire (not seen in recent years) and Northumberland, which is the only current site in England. The only known Welsh site is in Ceredigion (Cardiganshire), and it has not been seen here since 1967. In Scotland, it is recorded in Aberdeenshire, Dumfriesshire and Abernethy Forest in Inverness-shire but, here too, it has disappeared from two sites.
Outside of the UK, it has an extensive range across the lowlands of the northern hemisphere, although it is confined to the more northerly latitudes.
One of the reasons for the disappearance of this moss from two of the Scottish sites is due to the afforestation of much of these upland bogs. This dates from the time when upland mires and bogs were not considered to be sites worthy of protecting. As well as shading, the moss is affected by changes in the water quality, particularly increased acidity and higher nutrient levels. Drainage of bogs and peat-cutting are also potential threats to this species, along with inappropriate gathering of all sphagnum species by the horticultural trade and by local collectors.
Baltic bog moss is listed in the UK Biodiversity Action Plans (UK BAP), and is included in English Nature's Species Recovery Programme (SRP). The most important tasks behind protecting this moss are as follows: to re-survey those sites where it is known to have occurred in the past; ensure the survival of the moss where it is still found; establish ex-situ colonies (from British plants) to provide specimens for re-colonising suitable sites. It is also important that the precise habitat requirements of this species are known, particularly in view of its intolerance of poor water quality. It is hoped that more bryologists will be trained to identify this species and encouraged to report any new records. Finally, the indiscriminate collecting of sphagnum from the wild for use by the horticulture industry (for use in hanging baskets and displays) should be discouraged, perhaps by using local publicity and information boards at the appropriate sites.
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